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Background: The increasing use of kidneys from donations after cardiac death (DCD) for renal transplantation is hindered by negative outcomes owing to organ injury after prolonged warm and cold ischemia-reperfusion. Recently, hydrogen sulfide ([H.sub.2]S) has shown cytoprotective effects against ischemia-reperfusion injury; however, its effectiveness in the context of DCD renal transplantation is unknown. Methods: We tested a novel 30-day in vivo syngeneic murine model of DCD renal transplantation, in which the donor kidney was clamped for 30 minutes and stored for 18 hours in cold University of Wisconsin (UW) solution or UW with 150 [micro]M sodium hydrogen sulfide (UW + NaHS) before transplantation. We also tested a 7-day in vivo porcine model of DCD renal autotransplantation, in which the left kidney was clamped for 60 minutes and preserved for 24 hours using hypothermic perfusion with UW or UW + 150 [micro]M NaHS before autotransplantation. We collected blood and urine samples periodically, and collected kidney samples at the end point for histopathology and quantitative reverse transcription polymerase chain reaction. Results: Rats that received [H.sub.2]S-treated kidneys showed significantly higher survival, faster recovery of graft function and significantly lower acute tubular necrosis than controls. Pig kidneys perfused with UW + NaHS showed significantly higher renal blood flow and lower renal resistance than control kidneys after 24 hours of perfusion. After autotransplantation, pigs that received [H.sub.2]S-treated kidneys showed significantly lower serum creatinine on days 1 and 7 after transplantation. Rat and pig kidneys treated with [H.sub.2]S also showed more protective gene expression profiles than controls. Conclusion: Our findings support the potential use of [H.sub.2]S-supplemented UW solution during cold storage as a novel and practical means to improve DCD graft survival and function. Contexte : Il est difficile d'accroitre l'utilisation de reins provenant de dons apres deces car-diocirculatoire (DDC) aux fins de transplantation renale en raison des resultats negatifs dus aux lesions d'organe apres une ischemie-reperfusion chaude et froide prolongee. On a observe recemment que le sulfure d'hydrogene ([H.sub.2]S) exercait des effets cytoprotecteurs contre les lesions d'ischemie-reperfusion, mais on ignore encore s'il est efficace dans un contexte de transplantation renale provenant d'un DDC. Methodes : Nous avons mis a l'essai un nouveau modele murin syngenique in vivo de transplantation renale provenant d'un DDC sur 30 jours, dans lequel le rein du donneur a ete clampe pendant 30 minutes et conserve pendant 18 heures dans une solution froide de l'Universite du Wisconsin (UW) (UW + 150 [micro]m d'hydrogenosulfure de sodium [NaSH]) avant la transplantation. Nous avons egalement mis a l'essai un modele porcin in vivo d'autotransplantation renale provenant d'un DDC sur 7 jours, dans lequel le rein gauche a ete clampe pendant 60 minutes et conserve pendant 24 heures par perfusion hypothermique (avec UW ou UW + 150 [micro]M de NaSH) avant l'autotransplantation. Nous avons recueilli des echantillons de sang et d'urine regulierement et avons preleve des echantillons de rein au point final en vue de l'histopathologie et d'un test d'amplification en chaine par polymerase quantitative couple a une transcription inverse. Resultats : On a observe chez les rats ayant recu des reins traites au [H.sub.2]S un taux de survie significativement plus eleve, une recuperation plus rapide de la fonction du greffon et une necrose tubulaire aigue significativement plus faible que chez les temoins. Les reins de porc perfuses (UW + NaSH) ont montre un debit sanguin renal significativement plus eleve et une resistance renale plus faible que les temoins a la fin de la periode de perfusion de 24 heures. Apres l'autotransplantation, les porcs ayant recu des reins traites au [H.sub.2]S presentaient une creatinine serique significativement plus faible aux jours 1 et 7 apres la transplantation. Les reins de rat et de porc traites au [H.sub.2]S ont egalement montre des profils d'expression genique plus << protecteurs >> que les temoins. Conclusion : Nos conclusions appuient une eventuelle utilisation d'une solution UW enrichie en [H.sub.2]S pendant la conservation a froid comme nouveau moyen pratique d'ameliorer le taux de survie et la fonction du greffon lors de DDC., In 2017, 18 136 of 96 120 eligible patients received kidney transplants in the United States. (1) As demand for donor kidneys continues to exceed current supply, the use of [...]

We aimed to investigate whether the cardioprotection of sevoflurane against ischemia-reperfusion (IR) injury is via inhibiting endoplasmic reticulum stress. The rat in vivo model of myocardial IR injury was induced by ligation of the left anterior descending coronary artery. Sevoflurane significantly ameliorated the reduced cardiac function, increased infarct size, and elevated troponin I level and lactate dehydrogenase activity in plasma induced by IR injury. Sevoflurane suppressed the IR-induced myocardial apoptosis. The increased protein levels of glucose-regulated protein 78 and C/EBP homologous protein (CHOP) after myocardial IR were significantly reduced by sevoflurane. The protein levels of phosphorylated protein kinase RNA-like endoplasmic reticulum kinase (PERK), phosphorylated eukaryotic initiation factor 2 (eIF2a), and activating transcription factor 4 (ATF4) were significantly increased in rats with IR and attenuated by sevoflurane treatment. The phosphorylation of Akt was further activated by sevoflurane. The cardioprotection of sevoflurane could be blocked by wortmannin, a PI3K/Akt inhibitor. Our results suggest that the cardioprotection of sevoflurane against IR injury might be mediated by suppressing PERK/eIF2a/ATF4/CHOP signaling via activating the Akt pathway, which helps in understanding the novel mechanism of the cardioprotection of sevoflurane. Key words: sevoflurane, cardioprotection, ischemia-reperfusion injury, endoplasmic reticulum stress, Akt. Nous avons vise a etudier si l'effet cardioprotecteur du sevoflurane contre les lesions d'ischemie/reperfusion (IR) est lie a l'inhibition du stress du reticulum endoplasmique. Nous avons obtenu un modele de lesions d'IR myocardique in vivo chez le rat par l'occlusion de l'artere coronaire interventriculaire anterieure. Le sevoflurane a nettement permis d'attenuer le dysfonctionnement cardiaque engendre par les lesions d'IR, ainsi que de faire diminuer le degre d'augmentation de la taille de l'infarctus, des taux de troponine I et de l'activite de la deshydrogenase lactique plasmatiques engendres par les lesions d'IR. Le sevoflurane a permis de faire disparaitre l'apoptose engendree par l'IR dans le myocarde. Le sevoflurane a nettement permis faire diminuer le degre d'augmentation des taux de la proteine 78 regulee par le glucose et de la proteine homologue de la C/EBP (pour << CCAAT/enhancer-binding protein >>) ou CHOP observes apres l'IR myocardique. L'administration de sevoflurane a permis de faire diminuer le degre d'augmentation des taux de proteine PERK (pour << protein kinase RNA-like endoplasmic reticulum kinase >>) phosphorylee, de facteur eIF2a (pour << eukaryotic initiation factor 2 >>) phosphoryle et d'ATF4 (pour << activating transcription factor 4 >>) observees de facon notable chez les rats soumis a l'IR. Le sevoflurane permettait d'activer davantage la phosphorylation de l'Akt. Il etait possible d'inhiber les effets cardioprotecteurs du sevoflurane par la wortmannine, un inhibiteur de la voie de signalisation PI3K/Akt. Nos resultats laissent entendre que les effets cardioprotecteurs du sevoflurane contre les lesions d'IR pourraient etre medies par l'inhibition de l'axe PERK/eIF2a/ATF4/CHOP par l'intermediaire de l'activation de la voie de signalisation de l'Akt, ce qui contribue a la comprehension du nouveau mode d'action des effets cardioprotecteurs du sevoflurane. [Traduit par la Redaction] Mots-cles: sevoflurane, cardioprotection, lesions d'ischemie-reperfusion, stress du reticulum endoplasmique, Akt., Introduction Ischemic heart disease is still one of the leading causes of mortality and morbidity worldwide (Ferdinandy et al. 2007; Xia et al. 2016). Despite the development and improvement of [...]

Hydrogen sulfide ([H.sub.2]S), the third gas transmitter, has been proven to be neuroprotective in cerebral ischemic injury, but whether its effect is mediated by regulating autophagy is not yet clear. The present study was undertaken to explore the underlying mechanisms of exogenous [H.sub.2]S on autophagy regulation in cerebral ischemia. The effects and its connection with autophagy of NaHS, a [H.sub.2]S donor, were observed through neurological deficits and cerebral infarct volume in middle cerebral artery occlusion (MCAO) mice; autophagy-related proteins and autophagy complex levels in the ischemic hemisphere were detected with Western blot assay. Compared with the model group, NaHS significantly decreased infarct volume and improved neurological deficits; rapamycin, an autophagy activator, abolished the effect of NaHS; NaHS decreased the expression of LC3-II and up-regulated p62 expression in the ischemic cortex 24 h after ischemia. However, NaHS did not significantly influence Beclin-1 expression. [H.sub.2]S has a neuroprotective effect on ischemic injury in MCAO mice; this effect is associated with its influence in down-regulating autophagosome accumulation. Key words: exogenous hydrogen sulfide, MCAO, mice, autophagy, LC3-II. On a montre que le sulfure d'hydrogene, le troisieme neurotransmetteur gazeux, a des effets neuroprotecteurs en cas de lesion cerebrale ischemique, mais on n'a toujours pas etabli clairement si ses effets sont medies par la regulation de l'autophagie. Les presents travaux ont ete entrepris en vue d'etudier les mecanismes sous-jacents des effets du [H.sub.2]S exogene sur la regulation de l'autophagie dans l'ischemie cerebrale. Nous avons donc etudie les effets et le lien avec l'autophagie du NaHS, un donneur de [H.sub.2]S , en mesurant les deficits neurologiques et le volume de l'infarctus cerebral dans un modele d'occlusion de l'artere cerebrale moyenne (MCAO) chez la souris. Nous avons aussi mesure les taux des proteines liees a l'autophagie et des complexes d'autophagie dans l'hemisphere ischemique a l'aide de la technique d'immunobuvardage de western. L'administration de NaHS a permis de diminuer nettement le volume de l'infarctus et d'attenuer de facon marquee les deficits neurologiques par rapport au groupe de reference. Par contre, la rapamycine, un activateur de l'autophagie, a contre les effets du NaHS. En outre, 24 h apres l'ischemie, NaHS a entraine une diminution de l'expression du conjugue LC3-II et une regulation a la hausse de l'expression des proteines p62 dans le cortex ischemique. Par contre, le NaHS n'a pas influence l'expression de la proteine Becline-1 de facon notable. En somme, le [H.sub.2]S a des effets neuroprotecteurs sur les lesions ischemiques dans le modele de MCAO chez la souris; cet effet est associe a la regulation a la baisse de l'accumulation d'autophagosomes sous l'influence du gaz. [Traduit par la Redaction] Mots-cles : sulfure d'hydrogene exogene, MCAO, souris, autophagy, LC3-II., Introduction Hydrogen sulfide ([H.sub.2]S), formerly known as a toxic gas with an odorous smell, has been proven to be an endogenous signaling transmitter that regulates cellular function (Szabo 2007) and [...]

The aim of this study was to evaluate the protective effects of resveratrol and curcumin in an experimental rat model of intestinal ischemia-reperfusion (I/R). Forty-eight adult Wistar rats were used: 12 animals undergoing the sham surgery and 36 animals undergoing laparotomy, with 15 min of mesentric artery clamping. The animals from the latter group (n = 12) were pretreated, for 1 week, with vehicle (CTR), resveratrol (RES), and curcumin (CUR). After 1 h and 6 h of reperfusion, respectively, cyclooxigenase (COX)-2, mucin-1, E-cadherin, nuclear factor (NK)-κB expressions, and tumor necrosis factor related apoptosisinducing ligand (TRAIL) were assessed in the small intestine. Oxidative stress markers were determined in tissue homogenate and serum, and histopathological analysis was performed. Pretreatment with RES decreased the expression of COX-2 and NF-κB at both intervals and increased E-cadherin (p < 0.05) and mucin-1 production after 1 h. CUR had a beneficial effect on COX-2, NF-κB, and E-cadherin expressions, both after 1 h and after 6 h (p < 0.0001). The two compounds increased TRAIL levels and had a protective effect on oxidative stress and histopathological lesions, both after 1 h and after 6 h. Our results suggested that RES and CUR had beneficial effects in intestinal I/R and may represent a promising option for complementary treatment of this pathological condition. Key words: resveratrol, curcumin, oxidative stress, inflammation, intestinal ischemia. Cette etude avait pour but d'evaluer les effets protecteurs du resveratrol et de la curcumine dans un modele d'ischemie-reperfusion (I/R) intestinale chez le rat. Nous avons utilise 48 rats Wistar adultes : 12 animaux ont subi une intervention chirurgicale factice (sham) et 36 animaux ont subi une laparotomie avec occlusion de l'artere mesenterique de 15 minutes. Nous avions pretraite les animaux de ce dernier groupe avec le vehicule (Tem.), du resveratrol (RES) ou de la curcumine (CUR) pendant une semaine (n = 12 dans chacun des cas). Les animaux respectifs ont subi une reperfusion d'une heure ou de 6 heures, puis nous avons quantifie l'expression de la cyclooxygenase (COX)-2, de la mucine-1, de l'E-cadherin, ainsi que du facteur nucleaire (NK)-κB et du ligand inducteur de l'apoptose apparente au facteur de necrose tumorale (TRAIL) dans l'intestin grele. Nous avons evalue le stress oxydatif dans des homogenats de tissu et du serum a l'aide de marqueurs, et realise des examens histopathologiques. Le pretraitement avec le RES a entraine une diminution de l'expression de la COX-2 et du NF-κB (aux deux durees de perfusion) et une augmentation de la production d'E-cadherin (p < 0,05) et de mucine-1 (avec une reperfusion d'une heure). La CUR a eu un effet avantageux sur l'expression de la COX-2, du NF-κB et de l'E-cadherin (tant avec une reperfusion d'une heure que de 6 heures (p < 0,0001)). Les deux substances ont permis d'augmenter les taux de TRAIL et avaient un effet protecteur contre le stress oxydatif et dans les lesions visibles a l'examen histopathologique (tant apres une reperfusion d'une heure que de 6 heures). Nos resultats laissaient entendre que le RES et la CUR auraient des effets avantageux en cas d'ischemie intestinale et qu'ils pourraient representer un choix de traitement complementaire prometteur contre cet etat pathologique. [Traduit par la Redaction] Mots-cles : resveratrol, curcumine, stress oxydatif, inflammation, ischemie intestinale., Introduction Acute mesenteric ischemia, due to reduced splanchnic circulation followed by early revascularization, is the underlying mechanism that describes the phenomenon of intestinal ischemia-reperfusion (I/R). Intestinal I/R is a clinical [...]

Moutan cortex (MC) is a traditional Chinese medicine with diverse biological effects. The present study was performed to investigate the effects of MC on myocardial ischemia/reperfusion (I/R) in rats and to explore its possible mechanisms. Sprague-Dawley rats were administered MC extract (1.98 g/kg, i.g.) for 14 days and underwent a subsequent open-chest procedure involving 30 min of myocardial ischemia and 60 min of reperfusion. The cardioprotective effect of MC was demonstrated by reduced infarct size and marked improvement in the histopathological examination. The increase in the activity of superoxide dismutase (SOD) and glutathione (GSH) as well as the reduction of malondialdehyde (MDA) indicated that MC effectively promoted the anti-oxidative defense system. Increased anti-oxidative defense was accompanied by decreased release of lactate dehydrogenase (LDH) and creatine kinase (CK). The reduction in TUNEL-positive myocytes demonstrated that MC decreased myocardial apoptosis. The mRNA expression of B cell leukemia-2 (Bcl-2) was upregulated by MC and the ratio of Bcl-2/Bcl-2-associated X protein (Bax) mRNA expression was increased. MC pretreatment decreased the mRNA expression of inducible nitric oxide synthase (iNOS). The data from this study suggest that MC exerted protective effects on acute myocardial I/R injury via anti-oxidative and anti-apoptotic activities. Key words: Moutan cortex, ischemia/reperfusion, cardioprotective, anti- oxidative, anti-apoptotic. Le Cortex Moutan (CM) est un medicament traditionnel chinois qui exerce divers effets biologiques. L'etude presente a ete realisee afin d'examiner les effets de CM sur l'ischemie/reperfusion (I/R) chez le rat et d'explorer ses mecanismes d'action possibles. Des rats Sprague- Dawley ont recu un extrait de CM (1.98 g/kg, i.g.) pendant 14 jours et ils ont ete soumis a une intervention a thorax ouvert comportant une ischemie de 30 minutes et une reperfusion de 60 minutes. L'effet cardioprotecteur du CM a ete demontre par la reduction de la taille de l'infarctus et l'amelioration marquee de l'histopathologie. L'augmentation de l'activite de la superoxyde dismutase (SOD) et du glutathion (GSH) de meme que la reduction du malonaldehyde (MDA) indiquaient que le CM favorisait efficacement le systeme de defense antioxydant. L'augmentation de la defense antioxydante etait accompagnee d'une diminution de la liberation de lactate deshydrogenase (LDH) et de creatine kinase (CK). La reduction de myocytes positifs a la coloration TUNEL demontrait que le CM diminuait l'apoptose dans le myocarde. L'expression de l'ARNm de Bcl-2 etait regulee a la hausse par le CM et le rapport de l'expression des ARNm Bcl-2/Bax etait accru. Le pretraitement au CM diminuait l'expression de l'ARNm de la synthase d'oxyde nitrique inductible (iNOS). Les donnees de cette etude suggerent que le CM exerce des effets protecteurs envers le dommage d'I/R aigu dans le myocarde par ses activites antioxydantes et anti-apoptose. [Traduit par la Redaction] Mots-cles: cortex Moutan, ischemie/reperfusion, cardioprotecteur, antioxydant, anti-apoptose., Introduction The World Health Organization estimates that heart failure initiated by coronary heart disease and myocardial infarction is one of the leading causes of death worldwide (Venugopal et al. 2012). [...]

Abstract: Hyperthyroidism represents an increased risk factor for cardiovascular morbidity, especially when the heart is subjected to an ischemia/reperfusion process. The aim of this study was to explore the possible [...]

ABSTRACT Sodium danshensu (SDSS), the sodium salt of danshensu (DSS), has the same pharmacological effects as DSS. In the present study, we aimed to investigate the neuroprotective effect and possible [...]

Ischemic damage is recognized to cause cardiomyocyte (CM) death and myocardial dysfunction, but the role of cell-matrix interactions and integrins in this process has not been extensively studied. Expression of [...]

The phosphodie sterase type-5 inhibitor sildenafil has powerful cardioprotective effects against ischemia-reperfusion injury. PKG-mediated signaling has been implicated in this protection, although the mechanism and the downstream targets of this kinase remain to be fully elucidated. In this study we assessed the role of phospholemman (PLM) phosphorylation, which activates the [Na.sup.+]/[K.sup.+]-ATPase, in cardioprotection afforded by sildenafil administered during reperfusion. Isolated perfused mouse hearts were optimally protected against infarction (indexed by tetrazolium staining) by 0.1 [micro]M sildenafil treatment during the first 10 min of reperfusion. Extended sildenafil treatment (30, 60, or 120 min at reperfusion) did not alter the degree of protection provided. This protection was PKG dependent, since it was blocked by KT-5823. Western blot analysis using phosphospecific antibodies to PLM showed that sildenafil at reperfusion did not modulate PLM Ser63 or Set68 phosphorylation but significantly increased Ser69 phosphorylation. The treatment of isolated rat ventricular myocytes with sildenafil or 8-bromo-cGMP (PKG agonist) enhanced PLM Ser69 phosphorylation, which was bisindolylmaleimide (PKC inhibitor) sensitive. Patch-clamp studies showed that sildenafil treatment also activated the [Na.sup.+]/[K.sup.-]-ATPase, which is anticipated in light of PLM Ser69 phosphorylation. [Na.sup.+]/[K.sup.-]-ATPase activation during reperfusion would attenuate [Na.sup.+] overload at this time, providing a molecular explanation of how sildenafil guards against injury at this time. Indeed, using flame photometry and rubidium uptake into isolated mouse hearts, we found that sildenafil enhanced [Na.sup.+]/[K.sup.-]-ATPase activity during reperfusion. In this study we provide a molecular explanation of how sildenafil guards against myocardial injury during postischemic reperfusion. protein kinase G; sodium/potassium-adenosine 5'-triphosphatase; ischemia; heart doi: 10.1152/ajpheart.00129.2010.

The purpose of the present study was to assess whether resolvin E1 (RvE1), an anti-inflammatory mediator derived from eicosapentaenoic acid, would limit myocardial infarct size in the rat. The H9c2 cell line was used to assess whether RvE1 has direct protective effects on cardiomyocytes. In in vivo experiments, Male Sprague-Dawley rats underwent 30 min of ischemia/4 h of reperfusion. Before reperfusion, rats received intravenous RvE1 (0, 0.03, 0.1, or 0.3mg/kg). In in vitro experiments, H9c2 cells were incubated with RvE1 (0, 1, 10, 100, or 1000 nM). Cells were subjected to 18 h of incubation under normoxic conditions, 16 h of hypoxia, or 16 h of hypoxia and 2 h of reoxygenation. In vivo, RvE1 dose dependently reduced infarct size (30.7 [+ or -] 1.7% of the area at risk in the control group and 29.1 [+ or -] 1.6%, 14.7 [+ or -] 1.3%, and 9.0 [+ or -] 0.6% in the 0.03, 0.1, and 0.3 mg/kg groups, respectively, P < 0.001). In vitro, RvE1 increased viability and decreased apoptosis in a dose-dependent fashion in cells exposed to hypoxia or hypoxia/reoxygenation. A maximal effect was achieved at a concentration of 100 nM. RvE1 augmented phosphoinositide 3-kinase activity, attenuated caspase-3 activity, and augmented calciumdependent nitric oxide synthase activity in cells exposed to hypoxia or hypoxia/reoxygenation. RvE1 increased Akt, ERK1/2, and endothelial nitric oxide synthase phosphorylation and attenuated the levels of activated caspase-3 and phosphorylated p38 levels. AG-1478, an EGF receptor tyrosine kinase inhibitor, blocked the protective effect of RvE1 both in vivo and in vitro and attenuated the RvE1-induced increase in Akt and ERK1/2 phosphorylation. In conclusion, RvE1, an anti-inflammatory mediator derived from eicosapentaenoic acid, has a direct protective effect on cardiomyocytes against ischemia-reperfusion injury and limits infarct size when administered intravenously before reperfusion. infarct size; ischemia-reperfusion injury; apoptosis; epidermal growth factor receptor doi: 10.1152/ajpheart.01057.2009.

Ischemic postconditioning (PostC) and perconditioning (PerC) provide practical methods for protecting the heart against ischemia-reperfusion (I/R) injury, but their combined effects have not been studied in detail. Using an in vivo rat I/R model, we tested 1) whether additive effects were produced when local PostC was preceded by varying doses of remote PerC, and whether the optimal PostC+PerC regime is additive to local ischemic preconditioning (IPC), and 2) how combined PostC+PerC alters the activity of the reperfusion injury salvage kinase pathway. The optimal combination of PerC and PostC therapy was produced by PerC delivered with four cycles of 5 min of limb ischemia followed by 5-min reperfusion. This resulted in lower infarct size (22.56 [+ or -] 4.45%) compared with rats with PostC alone (29.39 [+ or -] 3.66%) and PerC alone (33.49 [+ or -] 5.81%) and complementary differences in the generation of reactive oxygen species and apoptotic signaling. However, this optimal combination of PostC+PerC resulted in protection similar to local IPC alone (18.8 [+ or -] 2.54%, P = 0.13), and when added to IPC there was no additional protection (19.62 [+ or -] 2.89%, P = 0.675). Akt and ERKI/2 phosphorylation was induced by PostC and PerC and maximally by combined PostC+PerC treatment, and protection was abolished by phosphatidylinositol 3-kinase or ERK1/2 inhibitors. This study shows that neither PostC nor a maximized 'dose' of PerC leads to optimal kinase signaling or cardioprotection compared with IPC alone. However, combined PostC+PerC may result in complementary effects on kinase signaling to recapitulate the effects of local IPC. Finally, combined PostC+PerC is not additive to IPC, suggesting that each works via a common pathway. apoptosis; ischemia-reperfusion; reactive oxygen species; survival kinase doi: 10.1152/ajpheart.01102.2009.

The female sex has been associated with improved myocardial salvage after ischemia and reperfusion (I/R). Estrogen, specifically 17[beta]-estradiol, has been demonstrated to mediate this phenomenon by limiting cardiomyocyte apoptosis. We sought to quantitatively assess the effect of sex, ovarian hormone loss, and I/R on myocardial Bax, Bcl-2, and apoptosis repressor with caspase recruitment domain (ARC) expression. Male (n = 48), female (n = 26), and oophorectomized female (n = 20) rabbits underwent 30 rain of regional ischemia and 3 h of reperfusion. The myocardial area at risk and infarct size were determined using a double-staining technique and planimetry. In situ oligo ligation was used to assess apoptotic cell death. Western blot analysis was used to determine proapoptotic (Bax) and antiapoptotic (Bcl-2 and ARC) protein levels in all three ischemic groups and, additionally, in three nonischemic groups. Infarct size (43.7 [+ or -] 3.2%) and apoptotic cell death (0.51 [+ or -] 0.10%) were significantly attenuated in females compared with males (56.4 [+ or -] 1.6%, P < 0.01, and 4.29 [+ or -] 0.95%, P < 0.01) and oophorectomized females (55.7 [+ or -] 3.4%, P < 0.05, and 4.36 [+ or -] 0.51%, P < 0.01). Females expressed significantly higher baseline ARC levels (3.62 [+ or -] 0.29) compared with males (1.78 [+ or -] 0.18, P < 0.01) and oophorectomized females (1.08 [+ or -] 0.26, P < 0.01). Males expressed a significantly higher baseline Bax-to-Bcl-2 ratio (4.32 [+ or -] 0.99) compared with females (0.65 [+ or -] 0.13, P < 0.01) and oophorectomized females (0.42 [+ or -] 0.10, P < 0.01). I/R significantly reduced Bax-to-Bcl-2 ratios in males. In all other groups, ARC levels and Bax-to-Bcl-2 ratios did not significantly change. These results support the conclusion that in females, endogenous estrogen limits I/R-induced cardiomyocyte apoptosis by producing a baseline antiapoptotic profile, which is associated with estrogen-dependent high constitutive myocardial ARC expression. 17[beta]-estradiol: cardiomyocyte apoptosis: apoptosis repressor with caspase recruitment domain: Bcl-2: Bax doi: 10.1152/ajpheart.01021.2009.

Chronic intermittent hypobaric hypoxia (CIHH) has an effective cardiac protection against ischemia-reperfusion injury. However, the underlying mechanisms are not fully known. It has been shown that blockade of [beta]-adrenergic receptor exerts anti-arrhythmic action and improves cardiac remodeling in ischemic myocardium. Thus we determined the influence of CIHH on [beta]-adrenergic receptor activity in right ventricular papillary muscle of rats. We found that the action potential duration in right ventricular papillary muscle was significantly longer in CIHH rats than in control rats. Activation of [beta]-adrenergic receptor with DL-isoproterenol dose-dependently increased action potential duration and the contractility in right ventricular papillary muscle. In CIHH rats, the prolonged effect of DL-isoproterenol on action potential duration and the positive inotropic effect were significantly decreased compared with that in control rats. Furthermore, radioligand-binding experiments revealed that the density and affinity of [beta]-adrenergic receptor in right ventricular myocardium was significantly lower in CIHH rats. In addition, Western blot analysis revealed that the membrane-bound G protein [G.sub.s][alpha] expression level in cardiac myocardium was significantly lower in CIHH rats than that in control rats. Collectively, these data suggest that CIHH suppresses [beta]-adrenergic receptor action in right ventricular papillary muscle through decreasing receptor density and affinity, as well as membrane-bound [G.sub.s][alpha]. This mechanism may be involved in the cardiac protective effect of CIHH. action potential; contraction; intermittent hypoxia; [beta]-adrenergic receptor; G protein doi: 10.1152/ajpheart.00410.2009.

Recent studies have implicated Toll-like receptor 2 (TLR2) and TLR4 signaling in delimiting liver and brain injury following ischemia-reperfusion (I/R). To determine whether TLR2 and TLR4 conferred cytoprotection in the heart, we subjected hearts of wild-type (WT) mice and mice deficient in TLR2 (TLR2D), TLR4 (TLR4D), and TIR domain-containing adapter protein (TIRAP-D) to ischemic preconditioning (IPC). Langendorff-perfused hearts were subjected to 30 min ischemia and 60 rain reperfusion with or without IPC. IPC resulted in a significant increase (P < 0.05) in the percent recovery of left ventricular developed pressure (%LVDP) in WT mouse hearts (54.4 [+ or -] 2.7% of baseline), whereas there was no significant increase in %LVDP (P > 0.05) in TIRAP-D mouse hearts (43.8 [+ or -] 1.9%) after I/R injury. IPC also resulted in a significant (P < 0.05) decrease in I/R-induced creatine kinase release and Evans blue dye uptake in WT but not TIRAP-D hearts. Interestingly, IPC resulted in a significant (P < 0.05) increase in %LVDP in TLR4-deficient hearts (52.7 [+ or -] 3%) but not in TLR2D hearts (39.3 [+ or -] 1.5%). Pretreatment with a specific TLR2 ligand (Pam3CSK) protected WT hearts against I/R-induced left ventricular dysfunction. The loss of IPC-induced cardioprotection in TIRAP-D mouse hearts was accompanied by a decreased translocation of protein kinase C-[epsilon] and decreased phosphorylation of GSK-3[beta]. Taken together, these data suggest that the cardioprotective effect of IPC is mediated, at least in part, through a TLR2-TIRAP-dependent pathway, suggesting that the modulation of this pathway represents a viable target for reducing I/R injury. myocardial dysfunction; ischemic preconditioning doi:10.1152/ajpheart.00306.2009

Cystathionine-[beta]-synthase (CBS) catalyzes the rate-limiting step in the transsulfuration pathway for the metabolism of homocysteine (Hcy) in the kidney. Our recent study demonstrates that ischemia-reperfusion reduces the activity of CBS leading to Hcy accumulation in the kidney, which in turn contributes to renal injury. CBS is also capable of catalyzing the reaction of cysteine with Hcy to produce hydrogen sulfide ([H.sub.2]S), a gaseous molecule that plays an important role in many physiological and pathological processes. The aim of the present study was to examine the effect of ischemia-reperfusion on CBS-mediated [H.sub.2]S production in the kidney and to determine whether changes in the endogenous [H.sub.2]S generation had any impact on renal ischemia-reperfusion injury. The left kidney of Sprague-Dawley rat was subjected to 45-min ischemia followed by 6-h reperfusion. The ischemia-reperfusion caused lipid peroxidation and cell death in the kidney. The CBS-mediated [H.sub.2]S production was decreased, leading to a significant reduction in the renal [H.sub.2]S level. The activity of cystathionine-[gamma]-lyase, another enzyme responsible for endogenous [H.sub.2]S generation, was not significantly altered in the kidney upon ischemia-reperfusion. Partial restoration of CBS activity by intraperitoneal injection of the nitric oxide scavenger, 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide not only increased renal [H.sub.2]S levels but also alleviated ischemia-reperfusion-induced lipid peroxidation and reduced cell damage in the kidney tissue. Furthermore, administration of an exogenous [H.sub.2]S donor, NaHS (100 [micro]g/kg), improved renal function. Taken together, these results suggest that maintenance of tissue [H.sub.2]S level may offer a renal protective effect against ischemia-reperfusion injury. homocysteine; oxidative stress; renal function; cystathionine-[gamma]-lyase

Nitric oxide (N[O.sup.*]) competitively inhibits oxygen consumption by mitochondria at cytochrome c oxidase and S-nitrosates thiol proteins. We developed mitochondria-targeted S-nitrosothiols (MitoSNOs) that selectively modulate and protect mitochondrial function. The exemplar MitoSNO1, produced by covalently linking an S-nitrosothiol to the lipophilic triphenylphosphonium cation, was rapidly and extensively accumulated within mitochondria, driven by the membrane potential, where it generated N[O.sup.*] and S-nitrosated thiol proteins. MitoSNO1-induced N[O.sup.*] production reversibly inhibited respiration at cytochrome c oxidase and increased extracellular oxygen concentration under hypoxic conditions. MitoSNO1 also caused vasorelaxation due to its N[O.sup.*] generation. Infusion of MitoSNO1 during reperfusion was protective against heart ischemia-reperfusion injury, consistent with a functional modification of mitochondrial proteins, such as complex I, following S-nitrosation. These results support the idea that selectively targeting N[O.sup.*] donors to mitochondria is an effective strategy to reversibly modulate respiration and to protect mitochondria against ischemia-reperfusion injury. nitric oxide | S-nitrosation

Byline: Ke-Xuan Liu (1), Yun-Sheng Li (1), Wen-Qi Huang (1), Shu-Qing Chen (2), Zhong-Xin Wang (1), Jia-Xin Liu (1), Zhengyuan Xia (3) Keywords: Postconditioning; Preconditioning; Intestinal reperfusion injury; Oxidative injury Abstract: Objective To test the hypothesis that immediate but not delayed ischemic postconditioning (IPo) during reperfusion attenuates intestinal injury, and that ischemic preconditioning (IPC) and IPo may confer synergy in intestinal protection. Design and setting Prospective laboratory animal study with concurrent control. Subjects Adult Sprague--Dawley rats. Interventions Intestinal ischemia/reperfusion (II/R) injury in rats was produced by clamping superior mesenteric artery for 60 min followed by 60 min reperfusion IPC was elicited by 10 min ischemia and 10 min reperfusion before index ischemia IPo was performed by three cycles of 30 s reperfusion and 30 s ischemia initiated either immediately at the onset of reperfusion (IPo) or after reperfusion for 3 min (delayed-IPo). Combination of IPC and IPo was performed by combining both protocols. Measurements and main results Intestinal ischemia/reperfusion resulted in significant intestinal injury evidenced as significant increase in Chiu's scores and wet-to-dry intestine weight ratio accompanied with increases in plasma levels of tumor necrosis factor-[alpha] and interleukin-6, as well as increases in the intestinal tissue lipid peroxidation product malonediadehyde and myeloperoxidase activity as compared to control animals (all P < 0.05). All these changes were significantly attenuated either by IPC or IPo or their combination (P < 0.05), and not by delayed-IPo (P > 0.05). IPC and IPo showed synergistic protection compared with either protocol alone. Conclusion Ischemic postconditioning reduces intestinal injury, in part, by inhibiting oxidative injury, neutrophils filtration and proinflammatory response. The early period of reperfusion is critical to intestinal protection by IPo, and intestinal protection with IPo can be enhanced by IPC. Author Affiliation: (1) Department of Anesthesiology, The First Affiliated Hospital, Sun Yat-sen University, No. 58, Zhongshan 2th Road, 510080, Guangzhou, China (2) Department of Gynecology and Obstetrics, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China (3) Department of Anesthesiology, Research Centre of Heart, Brain, Hormone and Healthy Aging, University of Hong Kong, 102 Pokfulam Road, Hong Kong SAR, China Article History: Registration Date: 22/01/2009 Received Date: 19/09/2008 Accepted Date: 19/01/2009 Online Date: 04/02/2009 Article note: K-X. Liu and Z. Xia share senior authorship. Electronic supplementary material The online version of this article (doi: 10.1007/s00134-009-1428-1) contains supplementary material, which is available to authorized users.

Among the cardiovascular pathologies, ischemic heart disease is a serious medical problem that can result in cardiac injury and (or) heart failure. The aim of the present study was to test the hypothesis that neuropeptide oxytocin induces cardioprotective effects on ischemia-reperfusion-induced myocardial damage. The functional parameters of isolated Langendorff-perfused rat hearts were recorded before and after global 25 min ischemia and subsequent reperfusion. The infarct size was determined by a computerized planimetric method. The results showed that oxytocin produced negative chronotropic effect even at low concentrations (90-125 nmol/L). Perfusion with oxytocin before ischemia resulted in significant reduction of the infarct size (p < 0.01), which was about 66% smaller than that in the control group. To evaluate the functional mechanisms involved, further experiments were performed under conditions of constant heart rate. The lower dose of oxytocin (90 nmol/L), which was ineffective in spontaneously beating hearts, induced a significant decrease of contractility. Elimination of the negative chronotropic effect of oxytocin prevented its cardioprotective action. In conclusion, our results demonstrated an attenuation of the infarct size in oxytocin-treated hearts, indicating a cardioprotective effect of oxytocin. The data suggest that the negative chronotropic action of oxytocin participates in its protective effects on ischemia-reperfusion-induced myocardial injury. Key words: cardioprotection, infarction, heart, ischemia, oxytocin, in vitro, peptide. Parmi les pathologies cardiovasculaires, la cardiopathie ischemique est associee aux problemes de sante graves et pourrait etre a l'origine d'une lesion et (ou) d'une insuffisance cardiaque. La presente etude a eu pour but de verifier l'hypothese que le neuropeptide oxytocine induit des effets cardioprotecteurs contre la lesion myocardique induite par l'ischemie/reperfusion. La taille de l'infarctus a ete determinee par une methode planimetrique informatisee. Les parametres fonctionnels du coeur de rat isole et perfuse selon la methode de Langendorff ont ete enregistres avant et apres une ischemie globale de 25 min suivie d'une reperfusion. Les resultats montrent que l'oxytocine a produit un effet chronotrope meme a faibles concentrations (90-125 nmol/L). Une perfusion d'oxytocine avant l'ischemie a provoque une reduction significative de la taille de l'infarctus (p < 0,01), qui a ete environ 66 % plus faible que celui observe chez le groupe temoin. Pour evaluer le mecanisme fonctionnel implique, d'autres experience ont ete effectuees dans des conditions de frequence cardiaque constante. La plus faible dose d'oxytocine (90 nmol/L), qui a ete inefficace dans les coeurs battant spontanement, a induit une diminution importante de la contractilite. L'elimination de l'effet chronotrope negatif de l' oxytocine a prevenu son action cardioprotectrice. Ainsi, les presents resultats demontrent une attenuation de la taille de l'infarctus dans les coeurs traites a l'oxytocine, ce qui denote un effet cardioprotecteur du neuropeptide. Les resultats obtenus donnent a penser que l'action inotrope negative de l'oxytocine pourrait participer a ses effets protecteurs contre la lesion myocardique induite par l'ischemie/reperfusion. Mots-cles : cardioprotection, infarctus, coeur, ischemie, oxytocine, in vitro, peptide. [Traduit par la Redaction], Introduction Although several studies have indicated that oxytocin modulates cardiovascular function, the results are not consistent. Oxytocinergic neurons are present in various brain areas related to cardiovascular regulation (Buijs 1983; [...]

We previously demonstrated that several clinically utilized volatile anesthetics including sevoflurane protected against renal ischemia-reperfusion (IR) injury by reducing necrosis and inflammation in vivo. We also demonstrated that volatile anesthetics produced direct anti-necrotic and anti-inflammatory effects in cultured renal tubules via mechanisms involving the externalization of phosphatidylserine and subsequent release of transforming growth factor (TGF)-[[beta].sub.1]. In this study, we tested the hypothesis that volatile anesthetic-mediated renal protection requires TGF-[[beta].sub.1] and SMAD3 signaling in vivo. We subjected TGF-[[beta].sub.1] +/+, TGF-[[beta].sub.1] +/-, SMAD3+/+, or SMAD3-/- mice to renal IR under anesthesia with pentobarbital sodium or with sevoflurane. Although TGF-[[beta].sub.1] +/+ and SMAD3+/+ mice were significantly protected against renal IR injury under sevoflurane anesthesia with reduced necrosis and inflammation, TGF-[[beta].sub.1] +/- mice and SMAD3-/- mice were not protected against renal IR with sevoflurane. Furthermore, a neutralizing TGF-[[beta].sub.1] antibody blocked renal protection with sevoflurane in TGF-[[beta].sub.1] +/+ mice. Sevoflurane caused nuclear translocation of SMAD3 and reduced the TNF-of-induced nuclear translocation of NF-[kappa]B in primary cultures of proximal tubules from TGF-[[beta].sub.1]+/+ but not in TGF-[[beta].sub.1]+/- mice. Finally, sevoflurane protected against necrosis induced with hydrogen peroxide in primary cultures of proximal tubules from TGF-[[beta].sub.1]/+ mice or SMAD3+/+ mice but not in proximal tubules from TGF[[beta].sub.1] +/- or SMAD3-/- mice. Therefore, we demonstrate in this study that sevoflurane-mediated renal protection in vivo requires the TGF[[beta].sub.1][right arrow] SMAD3 signaling pathway. acute renal failure; inflammation; necrosis; SMAD3

Consumption of flavonoid-rich foods and beverages is thought to reduce the risk of cardiovascular diseases. Whereas the biological activities of flavonoids have been characterized in vitro, there are no clear experimental data demonstrating that chronic dietary intake and intestinal absorption of flavonoids actually protects the heart against ischemia-reperfusion injury. We tested whether long-term consumption of specific flavonoids (anthocyanins) included in normal food could render the heart of rats more resistant to myocardial infarction. Maize kernels that differed specifically in their accumulation of anthocyanins were used to prepare rodent food in which anthocyanins were either present or absent. Male Wistar rats were fed the anthocyanin-rich (ACN-rich) or the anthocyanin-free (ACN-free) diet for a period of 8 wk. Anthocyanins were significantly absorbed and detected in the blood and urine of only rats fed the ACN-rich diet. In Langendorff preparations, the hearts of rats fed the ACN-rich diet were more resistant to regional ischemia and reperfusion insult. Moreover, on an in vivo model of coronary occlusion and reperfusion, infarct size was reduced in rats that ate the ACN-rich diet than in those that consumed the ACN-free diet (P < 0.01 ). Cardioprotection was associated with increased myocardial glutathione levels, suggesting that dietary anthocyanins might modulate cardiac antioxidant defenses. Our findings suggest important potential health benefits of foods rich in anthocyanins and emphasize the need to develop anthocyanin-rich functional foods with protective activities for promoting human health.

Bromelain (Br), a proteolytic enzyme extracted from the stem of the pineapple, is known to possess anti-inflammatory activity and has been shown to reduce blood viscosity, prevent the aggregation of blood platelets, and improve ischemia-reperfusion (I/R) injury in a skeletal muscle model. We investigated the capacity of Br to limit myocardial injury in a global I/R model. Adult male Sprague-Dawley rats were divided into two groups: control (PBS) and Br at 10 mg/kg in PBS administered via intraperitoneal injection (twice/day) for 15 consecutive days. On day 16, the hearts were excised and subjected to 30 min of global ischemia followed by 2 h of reperfusion. Br treatment showed higher left ventricular functional recovery throughout reperfusion compared with the controls [maximum rate of rise in intraventricular pressure (dP/[dt.sub.max]), 2,225 vs. 1,578 mmHg/s at 2 h reperfusion]. Aortic flow was also found to be increased in Br treatment when compared with that in untreated rats (11 vs. 1 ml). Furthermore, Br treatment reduced both the infarct size (34% vs. 43%) and the degree of apoptosis (28% vs. 37%) compared with the control animals. Western blot analysis showed an increased phosphorylation of both Akt and FOXO3A in the treatment group compared with the control. These results demonstrated for the first time that Br triggers an Akt-dependent survival pathway in the heart, revealing a novel mechanism of cardioprotective action and a potential therapeutic target against I/R injury. apoptosis; myocardial infarction; Ananas comosus; forkhead transcription factor

Nitrite has emerged as an endogenous signaling molecule with potential therapeutic implications for cardiovascular disease. Steady-state levels of nitrite are derived in part from dietary sources; therefore, we investigated the effects of dietary nitrite and nitrate supplementation and deficiency on NO homeostasis and on the severity of myocardial ischemia-reperfusion (MI/R) injury. Mice fed a standard diet with supplementation of nitrite (50 mg/liter) in their drinking water for 7 days exhibited significantly higher plasma levels of nitrite, exhibited significantly higher myocardial levels of nitrite, nitroso, and nitrosyl-heme, and displayed a 48% reduction in infarct size (Inf) after MI/R. Supplemental nitrate (1 g/liter) in the drinking water for 7 days also increased blood and tissue NO products and significantly reduced Inf. A time course of ischemia-reperfusion revealed that nitrite was consumed during the ischemic phase, with an increase in nitroso/nitrosyl products in the heart. Mice feda diet deficient in nitrite and nitrate for 7 days exhibited significantly diminished plasma and heart levels of nitrite and NO metabolites and a 59% increase in Inf after MI/R. Supplementation of nitrite in the drinking water for 7 days reversed the effects of nitrite deficiency. These data demonstrate the significant influence of dietary nitrite and nitrate intake on the maintenance of steady-state tissue nitrite/nitroso levels and illustrate the consequences of nitrite deficiency on the pathophysiology of MI/R injury. Therefore, nitrite and nitrate may serve as essential nutrients for optimal cardiovascular health and may provide a treatment modality for cardiovascular disease. dietary supplementation | myocardial infarction | nitric oxide

Despite years of experimental and clinical research, myocardial ischemia-reperfusion (IR) remains an important cause of cardiac morbidity and mortality. The transcription factor nuclear factor-[kappa]B (NF-[kappa]B) has been implicated as a key mediator of reperfusion injury. Activation of NF-[kappa]B is dependent upon the phosphorylation of its inhibitor, I[kappa]B[alpha], by the specific inhibitory [kappa]B kinase (IKK) subunit, IKK[beta]. We hypothesized that specific antagonism of the NF-[kappa]B inflammatory pathway through IKK[beta] inhibition reduces acute myocardial damage following IR injury. C57BL/6 mice underwent left anterior descending (LAD) artery ligation and release in an experimental model of acute IR. Bay 65-1942, an ATP-competitive inhibitor that selectively targets IKK[beta] kinase activity, was administered intraperitoneally either prior to ischemia, at reperfusion, or 2 h after reperfusion. Compared with untreated animals, mice treated with IKK[beta] inhibition had significant reduction in left ventricular infarct size. Cardiac function was also preserved following pretreatment with IKK[beta] inhibition. These findings were further associated with decreased expression of phosphorylated I[kappa]B[alpha] and phosphorylated p65 in myocardial tissue. In addition, IKK[beta] inhibition decreased serum levels of TNF-[alpha] and IL-6, two prototypical downstream effectors of NF-[kappa]B activity. These results demonstrate that specific IKK[beta] inhibition can provide both acute and delayed cardioprotection and offers a clinically accessible target for preventing cardiac injury following IR. inhibitory [kappa]B kinase-[beta]; myocardial infarction; nuclear factor-[kappa]B

Sphingosine 1-phosphate (S1P) is released at sites of tissue injury and effects cellular responses through activation of G protein-coupled receptors. The role of S1P in regulating cardiomyocyte survival following in vivo myocardial ischemia-reperfusion (I/R) injury was examined by using mice in which specific S1P receptor subtypes were deleted. Mice lacking either S1[P.sub.2] or S1[P.sub.3] receptors and subjected to 1-h coronary occlusion followed by 2 h of reperfusion developed infarcts equivalent to those of wild-type (WT) mice. However, in S1[P.sub.2,3] receptor double-knockout mice, infarct size following I/R was increased by >50%. I/R leads to activation of ERK, JNK, and p38 MAP kinases; however, these responses were not diminished in S1[P.sub.2,3] receptor knockout compared with WT mice. In contrast, activation of Akt in response to I/R was markedly attenuated in S1[P.sub.2,3] receptor knockout mouse hearts. Neither SI[P.sub.2] nor S1[P.sub.3] receptor deletion alone impaired I/R-induced Akt activation, which suggests redundant signaling through these receptors and is consistent with the finding that deletion of either receptor alone did not increase I/R injury. The involvement of cardiomyocytes in S1[P.sub.2] and S1[P.sub.3] receptor mediated activation of Akt was tested by using cells from WT and S1P receptor knockout hearts. Akt was activated by S1P, and this was modestly diminished in cardiomyocytes from S1[P.sub.2] or S1[P.sub.3] receptor knockout mice and completely abolished in the S1[P.sub.2,3] receptor double-knockout myocytes. Our data demonstrate that activation of S1[P.sub.2] and S1[P.sub.3] receptors plays a significant role in protecting cardiomyocytes from I/R damage in vivo and implicate the release of S1P and receptor-mediated Akt activation in this process. cardioprotection; mitogen-activated kinase; G protein-coupled receptors; infarct doi:10.1152/ajpheart.01331.2006

Abstract: The present study examines whether a subchronic probucol treatment of rats offers protection against ischemia-reperfusion JR) injury in isolated perfused hearts. Sprague-Dawley rats were treated every second day per [...]

Increased levels of protein O-linked N-acetylglucosamine (O-GlcNAc) have been shown to increase cell survival following stress. Therefore, the goal of this study was to determine whether in isolated neonatal rat ventricular myocytes (NRVMs) an increase in protein O-GlcNAcylation resulted in improved survival and viability following ischemia-reperfusion (I/R). NRVMs were exposed to 4 h of ischemia and 16 h of reperfusion, and cell viability, necrosis, apoptosis, and O-GlcNAc levels were assessed. Treatment of cells with glucosamine, hyperglycemia, or O-(2-acetamido-2-deoxy-D-glucopyranosylidene)-amino-N-phenylcarbamate (PUGNAc), an inhibitor of O-GlcNAcase, significantly increased O-GlcNAc levels and improved cell viability, as well as reducing both necrosis and apoptosis compared with untreated cells following I/R. Alloxan, an inhibitor of O-GlcNAc transferase, markedly reduced O-GlcNAc levels and exacerbated I/R injury. The improved survival with hyperglycemia was attenuated by azaserine, which inhibits glucose metabolism via the hexosamine biosynthesis pathway. Reperfusion in the absence of glucose reduced O-GlcNAc levels on reperfusion compared with normal glucose conditions and decreased cell viability. O-GlcNAc levels significantly correlated with cell viability during reperfusion. The effects of glucosamine and PUGNAc on cellular viability were associated with reduced calcineurin activation as measured by translocation of nuclear factor of activated T cells, suggesting that increased O-GlcNAc levels may attenuate I/R induced increase in cytosolic [Ca.sup.2+]. These data support the concept that activation of metabolic pathways leading to an increase in O-GlcNAc levels is an endogenous stress-activated response and that augmentation of this response improves cell survival. Thus strategies designed to activate these pathways may represent novel interventions for inducing cardioprotection. hexosamine biosynthesis; calcium; protein O-glycosylation

We previously showed that C-phycocyanin (PC), an antioxidant biliprotein pigment of Spirulina platensis (a blue-green alga), effectively inhibited doxorubicininduced oxidative stress and apoptosis in cardiomyocytes. Here we investigated the cardioprotective effect of PC against ischemia-reperfusion (I/R)-induced myocardial injury in an isolated perfused Langendorff heart model. Rat hearts were subjected to 30 min of global ischemia at 37[degrees]C followed by 45 min of reperfusion. Hearts were perfused with PC (10 [micro]M) or Spirulina preparation (SP, 50 mg/l) for 15 min before the onset of ischemia and throughout reperfusion. After 45 min of reperfusion, untreated (control) hearts showed a significant decrease in recovery of coronary flow (44%), left ventricular developed pressure (21%), and rate-pressure product (24%), an increase in release of lactate dehydrogenase and creatine kinase in coronary effluent, significant myocardial infarction (44% of risk area), and TdT-mediated dUTP nick end label-positive apoptotic cells compared with the preischemic state. PC or SP significantly enhanced recovery of heart function and decreased infarct size, attenuated lactate dehydrogenase and creatine kinase release, and suppressed I/R-induced free radical generation. PC reversed I/R-induced activation of p38 MAPK, Bax, and caspase-3, suppression of Bc1-2, and increase in TdT-mediated dUTP nick end label-positive apoptotic cells. However, I/R also induced activation of ERK I/2, which was enhanced by PC treatment. Overall, these results for the first time showed that PC attenuated I/R-induced cardiac dysfunction through its antioxidant and antiapoptotic actions and modulation of p38 MAPK and ERK 1/2. oxidative stress: apoptosis; Spirulina; antioxidant; reactive oxygen species; free radicals

MAP kinase activation is known to be deleterious not only to mitochondria but also to contractile function. Therefore, p38 MAP kinase inhibition therapy represents a promising approach in preventing reperfusion injury in the heart. However, reversal of p38 MAP kinase-mediated contractile dysfunction may disrupt the fragile sarcolemma of ischemic-reperfused myocytes. We, therefore, hypothesized that the beneficial effect of p38 MAP kinase inhibition during reperfusion can be enhanced when contractility is simultaneously blocked. Isolated and perfused rat hearts were paced at 330 rpm and subjected to 20 min of ischemia followed by reperfusion, p38 MAP kinase was activated after ischemia and early during reperfusion ( necrosis; contractility

Byline: Hayrettin Ozturk (1,5), Mustafa Aldemir (2), Ali Adeghsan Dokucu (1), Yusuf Yagmur (2), Nihal Kilinc (3), Ahmet Hikmet Sahin (4) Keywords: Intestinal ischemia and reperfusion injury; Molsidomine; NG-monomethyl-L-arginine Abstract: It is suggested that gastrointestinal mucosal blood flow depends on a balanced release of vasoactive substances from the endothelium. The present study investigated the effects of molsidomine on the small intestine after ischemia-reperfusion (I/R) injury in four groups of 10 rats each composed: (1) SO, sham operation (2) untreated I/R (3) ML, I/R plus molsidomine pretreatment (4) L-NAME, I/R plus N-omega-nitro-L-arginine methyl ester pretreatment. Intestinal ischemia for 45 min and reperfusion for 60 min were applied. Ileum specimens were obtained to determine the tissue level of malondialdehyde (MDA) and histologic changes. Mean MDA levels in the SO, untreated I/R, ML, and L-NAME groups were 95.60 +- 2.59, 136.90 +- 4.35, 121.10 +- 3.38, and 137.40 +- 4.42 nmol/g wet tissue, respectively. Although the MDA level in the ML group was higher than in the SO group (P &lt 0.0001), it was significantly lower compared to the untreated I/R and L-NAME groups (P &lt 0.0001, P &lt 0.0001). Mucosal injury scores (MIS) in groups 1--4 were 0.2 +- 0.42, 3.9 +- 0.73, 1.5 +- 0.70, and 4.1 +- 0.56, respectively. In group 3 the MIS was significantly lower than in groups 2 and 4 (P &lt 0.0001, P &lt 0.0001). Molsidomine plays a role in attenuating reperfusion injury of the small intestine by depression of tissue MDA levels and MIS and regulates post-ischemic intestinal perfusion while restoring the intestinal microcirculatory blood flow and histologic injury. Author Affiliation: (1) Department of Pediatric Surgery, Dicle University Medical School, DiyarbakA+-r, Turkey (2) Department of General Surgery, Dicle University Medical School, DiyarbakA+-r, Turkey (3) Department of Pathology, Dicle University Medical School, DiyarbakA+-r, Turkey (4) Department of Pediatric Surgery, Soma SSK Hospital, Manisa, Turkey (5) Dicle University Medical School, Department of Pediatric Surgery, 21280 DiyarbakA+-r, Turkey Article History: Accepted Date: 25/04/2001 Online Date: 03/06/2003

[A.sub.3] adenosine receptor (AR) activation and inhibition worsen and improve, respectively, renal function after ischemia-reperfusion (I/R) injury in rats. We sought to further characterize the role of [A.sub.3] ARs in modulating renal function after either I/R or myoglobinuric renal injury. [A.sub.3] knockout mice had significantly lower plasma creatinines compared with C57 controls 24 h after I/R or myoglobinuric renal injury. C57 control mice pretreated with the [A.sub.3] AR antagonist [3-ethyl-5-benzyl-2-methyl-4-phenylethynyl-6-phenyl-l,4-([+ or -])-dihydropyridine-3,5 dicarboxylate] or agonist [0.125 mg/kg [N.sup.6]-(3-iodobenzyl)-N-methyl-5'-carbamoyladenosine (IB-MECA)] demonstrated improved or worsened renal function, respectively, after I/R or myoglobinuric renal injury. Higher doses of IB-MECA were lethal in C57 mice subjected to renal ischemia. [H.sub.1] but not [H.sub.2] histamine receptor antagonist prevented death in mice pretreated with IB-MECA before renal ischemia. Improvement in renal function was associated with significantly improved renal histology. In conclusion, preischemic [A.sub.3] AR activation (0.125 mg/kg IB-MECA) exacerbated renal I/R injury in mice. Mice lacking [A.sub.3] ARs or blocking [A.sub.3] ARs in wild-type mice resulted in significant renal protection from ischemic or myoglobinuric renal failure. acute renal failure; histamine; ischemic-reperfusion injury

These experiments were designed to determine whether green tea extract (GTE), which contains polyphenolic free radical scavengers, prevents ischemia-reperfusion injury to the liver. Rats were fed a powdered diet containing 0-0.3% GTE starting 5 days before hepatic warm ischemia and reperfusion. Free radicals in bile were trapped with the spin-trapping reagent [alpha]-(4-pyridyl-1-oxide)-N-tert-butylnitrone (4-POBN) and measured using electron spin resonance spectroscopy. Hepatic ischemia-reperfusion increased transaminase release and caused pathological changes including focal necrosis and hepatic leukocyte infiltration in the liver. Transaminase release was diminished by over 85% and pathological changes were almost totally blocked by 0.1% dietary GTE. Ischemia-reperfusion increased 4-POBN/radical adducts in bile nearly twofold, an effect largely blocked by GTE. Epicatechin, one of the major green tea polyphenols, gave similar protection as GTE. In addition, hepatic ischemia-reperfusion activated NF-KB and increased TNF-[alpha] mRNA and protein expression. These effects were all blocked by GTE. Taken together, these results demonstrate that GTE scavenges free radicals in the liver after ischemia-reoxygenation, thus preventing formation of toxic cytokines. Therefore, GTE could prove to be effective in decreasing hepatic injury in disease states where ischemia-reperfusion occurs. ischemia; free radicals; liver; nuclear factor-kappaB; cytokines

Sildenafil citrate (Viagra) is the pharmacological agent used to treat erectile dysfunction in men. Because this drug has a vasodilatory effect, we hypothesized that such an action may induce a preconditioning-like cardioprotective effect via opening of mitochondrial ATP-sensitive K ([K.sub.ATP]) channels. Rabbits were treated with sildenafil citrate (0.7 mg/kg iv) either 30 min (acute phase) or 24 h (delayed phase) before 30 min of ischemia and 3 h of reperfusion. Mitochondrial [K.sub.ATP] channel blocker 5-hydroxydecanoate (5-HD, 5 mg/kg iv) was given 10 min before ischemia-reperfusion. Infarct size was measured by tetrazolium staining. Sildenafil caused reduction in arterial blood pressure within 2 min of treatment, which returned to nearly baseline levels 3 min later. The infarct size (% risk area, means [+ or -] SE) reduced from 33.8 [+ or -] 1.7 in control rabbits to 10.8 [+ or -] 0.9 during the acute phase (68% reduction, P < 0.05) and 19.9 [+ or -] 2.0 during the delayed phase (41% reduction, P < 0.05). 5-HD abolished protection with an increase in infarct size to 35.6 [+ o r -] 0.4% and 36.8 [+ or -] 1.6% during the acute and delayed phase, respectively (P < 0.05). Similar acute and delayed cardioprotective effects were observed when sildenafil was administered orally. Systemic hemodynamics also decreased after oral administration of the drug. However, these changes were mild and occurred slowly. For the first time, we demonstrate that sildenafil induces acute and delayed protective effects against ischemia-reperfusion injury, which are mediated by opening of mitochondrial [K.sub.ATP] channels. ATP-sensitive potassium channel; ischemia-reperfusion; phosphodiesterase-5

To find a protein kinase C (PKC)-independent preconditioning mechanism, hypoxic preconditioning (HP; i.e., 10-min anoxia and 10-min reoxygenation) was applied to isolated rat hearts before 60min global ischemia. HP led to improved recovery of developed pressure and reduced end-diastolic pressure in the left ventricle during reperfusion. Protection was unaffected by the PKC inhibitor bisindolylmaleimide (BIM; 1 [micro]mol/1). It was abolished by the inhibitor of protein phosphatases 1 and 2A cantharidin (20 or 5 [micro]mol/l) and partially enhanced by the inhibitor of protein phosphatase 2A okadaic acid (5 nmol/l). In adult rat cardiomyocytes treated with BIM and exposed to 60-min simulated ischemia (anoxia, extracellular pH 6.4), HP led to attenuation of anoxic [Na.sup.+]/[Ca.sup.2+] overload and of hypercontracture, which developed on reoxygenation. This protection was prevented by treatment with cantharidin but not with okadaic acid. In conclusion, HP exerts PKC-independent protection on ischemic-reperfused rat hearts and cardiomyocytes. Protein phosphatase 1 seems a mediator of this protective mechanism. cellular calcium; heart function; ischemia; reperfusion

Erythropoietin (EPO) plays an important role in the brain's response to neuronal injury. Systemic administration of recombinant human EPO (rhEPO) protects neurons from injury after middle cerebral artery occlusion, traumatic brain injury, neuroinflammation, and excitotoxicity. Protection is in part mediated by antiapoptotic mechanisms. We conducted parallel studies of rhEPO in a model of transient global retinal ischemia induced by raising intraocular pressure, which is a clinically relevant model for retinal diseases. We observed abundant expression of EPO receptor (EPO-R) throughout the ischemic retina. Neutralization of endogenous EPO with soluble EPO-R exacerbated ischemic injury, which supports a crucial role for an endogenous EPO/EPO-R system in the survival and recovery of neurons after an ischemic insult. Systemic administration of rhEPO before or immediately after retinal ischemia not only reduced histopathological damage but also promoted functional recovery as assessed by electroretinography. Exogenous EPO also significantly diminished terminal deoxynucleotidyltransferase-mediated dUTP end labeling labeling of neurons in the ischemic retina, implying an antiapoptotic mechanism of action. These results further establish EPO as a neuroprotective agent in acute neuronal ischemic injury.

Mechanisms by which opening the mitochondrial ATP-sensitive [K.sup.+] channel protects the ischemic heart. Am J Physiol Heart Circ Physiol283: H284-H295, 2002. First published February 14, 2002; 10.1152/ajpheart. 00034.2002.--Diazoxide opening of the mitochondrial ATP-sensitive [K.sup.+] (mito[K.sub.ATP]) channel protects the heart against ischemia-reperfusion injury by unknown mechanisms. We investigated the mechanisms by which miKATP to channel opening may act as an end effector of cardioprotection in the perfused rat heart model, in permeabilized fibers, and in rat heart mitochondria. We show that diazoxide pretreatment preserves the normal low outer membrane permeability to nucleotides and cytochrome c and that these beneficial effects are abolished by the mitoKATP channel inhibitor 5-hydroxydecanoate. We hypothesize that an open mito[K.sub.ATP] channel during ischemia maintains the tight structure of the intermembrane space that is required to preserve the normal low outer membrane permeability to ADP and ATP. This hypothesis is supported by findings in mitochondria showing that small decreases in intermembrane space volume, induced by either osmotic swelling or diazoxide, increased the half-saturation constant for ADP stimulation of respiration and sharply reduced ATP hydrolysis. These effects are proposed to lead to preservation of adenine nucleotides during ischemia and efficient energy transfer upon reperfusion. mitochondria; metabolism; creatine kinase; membrane transport; cytochrome c; ischemic preconditioning

Ischemia/reperfusion (I/R) injury is a serious potential threat to outcomes in organ transplantation and other clinical arenas in which there is temporary interruption of blood flow. I/R is a frequent cause of primary failure in organ transplantation. We hypothesized that the antioxidant bucillamine, a potent sulfhydryl donor, would protect against I/R injury in high-risk organ transplants. Because livers subjected to prolonged ischemia and very fatty livers are highly susceptible to severe I/R injury, we studied the effect of bucillamine in three animal models of liver transplantation: two ex vivo models of isolated perfused livers, either normal or fatty rat livers, and an in vivo model of syngenic orthotopic liver transplants in rats. In all models, livers were deprived of oxygen for 24 h before either ex vivo reperfusion or transplantation. In the ex vivo models, bucillamine treatment significantly improved portal vein blood flow and bile production, preserved normal liver architecture, and significantly reduced liver enzyme release and indices of oxidative stress. Moreover, bucillamine treatment significantly increased levels of reduced glutathione in the liver and lowered levels of oxidized glutathione in both liver and blood. In rats subjected to liver transplants, bucillamine significantly enhanced survival and protected against hepatic injury. Possible mechanisms of this protection include prevention of excessive accumulation of toxic oxygen species, interruption of redox signaling in hepatocytes, and inhibition of macrophage activation. This study demonstrates the potential utility of bucillamine or other cysteine-derived thiol donors for improving outcomes in organ transplantation and other clinical settings involving I/R injury.

The cardioprotective effects of aldose reductase inhibition on ischemic myocardium were investigated in isolated heart preparations from control and diabetic hearts using an ischemia-reperfusion model in the absence or presence of an aldose reductase inhibitor, zopolrestat. Results show that the inhibition of aldose reductase resulted in higher levels of high-energy phosphate bonds in the myocardium. The implications of these findings on the management of ischemic heart disease are discussed.

The signaling mechanism responsible for the cardioprotective effects of alcohol consumption was investigated using isolated hearts from guinea pigs and rats. The cardioprotection derived from alcohol was found to be similar to that brought about by ischemic preconditioning. Receptor blocking studies revealed that reperfusion injury prevention is mediated by adenosine among guinea pigs and by alpha-1 adrenergic receptors among rats.

Reperfusion injury, which occurs upon the reintroduction of blood flow to an ischemic organ, is responsible for considerable damage in heart attacks and strokes. However, no treatment for reperfusion injury is currently available. A major cause of reperfusion injury is the iron-mediated generation of hydroxyl radical (*OH). In this study we have explored the capacity of novel iron chelators called 'exochelins' to prevent reperfusion injury. Exochelins, siderophores of Mycobacterium tuberculosis, are unique iron chelators because they are lipid soluble, and hence able to enter cells rapidly. In the iron-free state, exochelins prevented *OH formation. Desferri-exochelins prevented oxidative injury to cultured cardiac myocytes, and did so more rapidly and effectively than the nonlipid soluble iron chelator deferoxamine. The capacity of various desferri-exochelins to protect myocytes from oxidative injury varied directly with their solubility in lipid. Infused into isolated rabbit hearts during reperfusion after a period of ischemia, desferri-exochelins dramatically improved systolic and diastolic left ventricular function, preserved coronary flow, reduced release of the cardiac enzyme lactic dehydrogenase, and reduced myocardial concentrations of *OH metabolites. Thus, highly diffusible desferri-exochelins block injury caused by *OH production and have potential for the treatment of reperfusion injury.