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5-[5-(2-Nitrophenyl) furfuryliodine]-1,3-diphenyl-2-thiobarbituric acid (UCF-101) is a protease inhibitor which was reported to protect against ischaemic heart damage and apoptosis. This study evaluated the impact of UCF-101 on steptozotocin (STZ)-induced diabetic cardiomyocyte dysfunction. Adult FVB mice were made diabetic with a single injection of STZ (200 mg kg(1)). Two weeks after STZ injection, cardiomyocytes from control and STZ-treated mice were isolated and treated with UCF-101 (20 mum for 1 h). Cardiomyocyte contractile properties were analysed, including peak shortening (PS), maximal velocity of shortening/relengthening (+/-dL/dt), time to PS (TPS) and time to 90% relengthening (TR(90)). Steptozotocin-induced diabetes depressed PS and +/-dL/dt and prolonged TPS and TR(90) in cardiomyocytes, all of which were significantly alleviated by UCF-101. Immunoblotting analysis showed that UCF-101 significantly alleviated STZ-induced loss of phospholamban phosphorylation without affecting sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA2a) and phospholamban. Steptozotocin reduced AMP-activated protein kinase (AMPK) phosphorylation at Thr172 of the catalytic subunit without affecting total AMPK expression, which was restored by UCF-101. Short-term exposure to UCF-101 did not change the expression of X-linked inhibitor of apoptosis protein (XIAP) and Omi stress-regulated endoprotease, high temperature requirement protein A2 (Omi/HtrA2), favouring an apoptosis-independent mechanism. Both the AMPK activator resveratrol and the antioxidant N-acetylcysteine mimicked the UCF-101-induced beneficial effect in STZ-induced diabetic cardiomyocytes. In addition, UCF-101 promoted the phosphorylation of p38 mitogen-activated protein kinases and c-Jun N-terminal kinase (JNK) after 15 min of incubation, while it failed to affect the phosphorylation of extracellular signal-regulated kinase (ERK) and glycogen synthase kinase-3beta (GSK-3beta) within 120 min in H9C2 myoblasts. Taken together, these results indicate that UCF-101 protects against STZ-induced cardiomyocyte contractile dysfunction, possibly via an AMPK-associated mechanism.

Background: Sepsis and septic shock are known to prompt multiple organ failure including cardiac contractile dysfunction, which is typically referred to as septic cardiomyopathy. Among various theories postulated for the etiology of septic cardiomyopathy, mitochondrial injury (both morphology and function) in the heart is perceived as the main culprit for reduced myocardial performance and ultimately heart failure in the face of sepsis. Methods: Over the past decades, ample of experimental and clinical work have appeared, focusing on myocardial mitochondrial changes and related interventions in septic cardiomyopathy. Results and Conclusion: Here we will briefly summarize the recent experimental and clinical progress on myocardial mitochondrial morphology and function in sepsis, and discuss possible underlying mechanisms, as well as the contemporary interventional options.

Endothelin (ET)-1 is implicated in the pathophysiology of cardiovascular diseases although its role in obesity anomalies has not been fully elucidated. This study was designed to examine the impact of ET-1 receptor A (ETA) ablation on obesity-induced changes in cardiac geometry and contractile function, as well as the mechanisms involved with a focus on autophagy. Cardiomyocyte-specific ETA receptor knockout (ETAKO) and WT mice were fed either low-fat (10% calorie from fat) or high-fat (45% calorie from fat) diet for 24 weeks. Glucose tolerance test was examined to confirm insulin resistance. High-fat diet intake compromised myocardial geometry (enlarged left ventricular diameters in systole and diastole), morphology (cardiac hypertrophy, increased wall thickness and interstitial fibrosis), contractile function (reduced fractional shortening, ejection fraction and cardiomyocyte shortening) and intracellular Ca2+ handling, the effect of which was significantly attenuated by ETAKO. TUNEL staining revealed overt apoptosis in high-fat-fed group, the effect was reverted by ETAKO. Western blot analysis noted that high-fat intake downregulated leptin receptor and PPARγ, insulin signaling (elevated basal/dampened insulin-stimulated phosphorylation of Akt and IRS1), phosphorylation of AMPK, ACC, upregulated GATA-4, ANP, NFATc3, PPARα, m-TOR/p70s6k signaling, which were attenuated by ETAKO with the exception of AMPK/ACC. Furthermore, high-fat intake suppressed cardiac autophagy, which was abrogated by ETAKO. In cultured murine cardiomyocytes, palmitic acid challenged mimicked high-fat diet-induced hypertrophic and autophagic responses, the effect of which were abolished by the ETA receptor antagonist BQ123 or mTOR inhibitor rapamycin. These results suggest that inhibition of ETA rescues high-fat intake-induced cardiac anomalies possibly through autophagy regulation.

BACKGROUND AND PURPOSE: Lipopolysaccharides (LPS), an outer membrane component of Gram‐negative bacteria, triggers myocardial anomalies in sepsis. Recent findings indicated a role for inflammatory cytokine MIF and its receptor, CD74, in septic organ injury, although little is known of the role of MIF‐CD74 in septic cardiomyopathy. EXPERIMENTAL APPROACH: This study evaluated the impact of CD74 ablation on endotoxaemia‐induced cardiac anomalies. Echocardiographic, cardiomyocyte contractile and intracellular Ca(2+) properties were examined. KEY RESULTS: Our data revealed compromised cardiac function (lower fractional shortening, enlarged LV end systolic diameter, decreased peak shortening, maximal velocity of shortening/relengthening, prolonged duration of relengthening and intracellular Ca(2+) mishandling) and ultrastructural derangement associated with inflammation, O(2) (−) production, apoptosis, excess autophagy, phosphorylation of AMPK and JNK and dampened mTOR phosphorylation. These effects were attenuated or mitigated by CD74 knockout. LPS challenge also down‐regulated Skp2, an F‐box component of Skp1/Cullin/F‐box protein‐type ubiquitin ligase, while up‐regulating that of SUV39H1 and H3K9 methylation of the Bcl2 protein BCLB. These effects were reversed by CD74 ablation. In vitro study revealed that LPS facilitated GFP‐LC3B formation and cardiomyocyte defects. These effects were prevented by CD74 ablation. Interestingly, the AMPK activator AICAR, the autophagy inducer rapamycin and the demethylation inhibitor difenoconazole inhibited the effects of CD74 ablation against LPS‐induced cardiac dysfunction, while the SUV39H1 inhibitor chaetocin or methylation inhibitor 5‐AzaC ameliorated LPS‐induced GFP‐LC3B formation and cardiomyocyte contractile dysfunction. CONCLUSION AND IMPLICATIONS: Our data suggested that CD74 ablation protected against LPS‐induced cardiac anomalies, O(2) (−) production, inflammation and apoptosis through suppression of autophagy in a Skp2‐SUV39H1‐mediated mechanism.

In patients with sepsis, lipopolysaccharide (LPS) from the outer membrane of gram-negative bacteria triggers cardiac dysfunction and heart failure, but target therapy for septic cardiomyopathy remains unavailable. In this study we evaluated the beneficial effects of cardamonin (CAR), a flavone existing in Alpinia plant, on endotoxemia-induced cardiac dysfunction and the underlying mechanisms with focus on oxidative stress and apoptosis. Adult mice were exposed to LPS (4 mg/kg, i.p. for 6 h) prior to functional or biochemical assessments. CAR (20 mg/kg, p.o.) was administered to mice immediately prior to LPS challenge. We found that LPS challenge compromised cardiac contractile function, evidenced by compromised fractional shortening, peak shortening, maximal velocity of shortening/relengthening, enlarged LV end systolic diameter and prolonged relengthening in echocardiography, and induced apoptosis, overt oxidative stress (O(2)(−) production and reduced antioxidant defense) associated with inflammation, phosphorylation of NF-κB and cytosolic translocation of transcriptional factor Nrf2. These deteriorative effects were greatly attenuated or mitigated by CAR administration. However, H&E and Masson’s trichrome staining analysis revealed that neither LPS challenge nor CAR administration significantly affected cardiomyocyte cross-sectional area and interstitial fibrosis. Mouse cardiomyocytes were treated with LPS (4 µg/mL) for 6 h in the absence or presence of CAR (10 μM) in vitro. We found that addition of CAR suppressed LPS-induced defect in cardiomyocyte shortening, which was nullified by the Nrf2 inhibitor ML-385 or the NF-κB activator prostratin. Taken together, our results suggest that CAR administration protects against LPS-induced cardiac contractile abnormality, oxidative stress, apoptosis, and inflammation through Nrf2- and NF-κB-dependent mechanism.

Endoplasmic reticulum (ER) stress has been demonstrated to prompt various cardiovascular risks although the underlying mechanism remains elusive. Protein tyrosine phosphatase-1B (PTP1B) serves as an essential negative regulator for insulin signaling. This study examined the role of PTP1B in ER stress-induced myocardial anomalies and underlying mechanism involved with a focus on autophagy. WT and PTP1B knockout mice were subjected to the ER stress inducer tunicamycin (1mg/kg). Cardiac function was evaluated with echocardiography and an Ion-Optix MyoCam system. Western blot analysis was used to monitor the levels of ER stress, autophagy and insulin signaling including insulin receptor substrate (IRS), tribbles homolog 3 (TRIB3), Atg5/7, p62 and LC3-II. Our results showed that ER stress resulted in compromised echocardiographic and cardiomyocyte contractile function, intracellular Ca2+ mishandling, ER stress, O2- production, apoptosis, the effects of which (with the exception of ER stress) were significantly attenuated or negated by PTP1B ablation. Levels of serine phosphorylation of IRS-1, TRIB3, Atg5/7, LC3B and the autophagy adaptor p62 were significantly upregulated while IRS-1 tyrosine phosphorylation was reduced by tunicamycin, the effect of which were obliterated by PTP1B ablation. In vitro study revealed that the autophagy inducer rapamycin and TRIB3 overexpression cancelled PTP1B ablation-offered beneficial effects on cardiomyocyte function or O2- production in murine cardiomyocytes or H9C2 myoblasts. Antioxidant or gene silencing of TRIB3 mimicked PTP1B ablation-induced protective effects. These findings collectively suggested that PTP1B ablation protects against ER stress-induced cardiac anomalies through regulation of autophagy.

Lipopolysaccharide (LPS), an essential component of outer membrane of the Gram-negative bacteria, plays a pivotal role in myocardial anomalies in sepsis. Recent evidence depicted an essential role for mitochondrial aldehyde dehydrogenase (ALDH2) in cardiac homeostasis. This study examined the effect of ALDH2 on endotoxemia-induced cardiac anomalies. Echocardiographic, cardiac contractile and intracellular Ca2+ properties were examined. Our results indicated that LPS impaired cardiac contractile function (reduced fractional shortening, LV end systolic diameter, peak shortening, maximal velocity of shortening/relengthening, prolonged relengthening duration, oxidation of SERCA, and intracellular Ca2+ mishandling), associated with ER stress, inflammation, O2- production, increased autophagy, CAMKKβ, phosphorylated AMPK and suppressed phosphorylation of mTOR, the effects of which were significantly attenuated or negated by ALDH2. LPS promoted early endosomal formation (as evidenced by RAB4 and RAB5a), apoptosis and necrosis (MTT and LDH) while decreasing late endosomal formation (RAB7 and RAB 9), the effects were reversed by ALDH2. In vitro study revealed that LPS-induced SERCA oxidation, autophagy and cardiac dysfunction were abrogated by ALDH2 activator Alda-1, the ER chaperone TUDCA, the autophagy inhibitor 3-MA, or the AMPK inhibitor Compound C. The beneficial effect of Alda-1 against LPS was nullified by AMPK activator AICAR or rapamycin. CAMKKβ inhibition failed to rescue LPS-induced ER stress. Tunicamycin-induced cardiomyocyte dysfunction was ameliorated by Alda-1 and autophagy inhibition, the effect of which was abolished by rapamycin. These data suggested that ALDH2 protected against LPS-induced cardiac anomalies via suppression of ER stress, autophagy in a CAMKKβ/AMPK/mTOR-dependent manner.

Uncorrected obesity has been associated with cardiac hypertrophy and contractile dysfunction. Several mechanisms for this cardiomyopathy have been identified, including oxidative stress, autophagy, adrenergic and renin-angiotensin aldosterone overflow. Another process that may regulate effects of obesity is epigenetics, which refers to the heritable alterations in gene expression or cellular phenotype that are not encoded on the DNA sequence. Advances in epigenome profiling have greatly improved the understanding of the epigenome in obesity, where environmental exposures during early life result in an increased health risk later on in life. Several mechanisms, including histone modification, DNA methylation and non-coding RNAs, have been reported in obesity and can cause transcriptional suppression or activation, depending on the location within the gene, contributing to obesity-induced complications. Through epigenetic modifications, the fetus may be prone to detrimental insults, leading to cardiac sequelae later in life. Important links between epigenetics and obesity include nutrition, exercise, adiposity, inflammation, insulin sensitivity and hepatic steatosis. Genome-wide studies have identified altered DNA methylation patterns in pancreatic islets, skeletal muscle and adipose tissues from obese subjects compared with non-obese controls. In addition, aging and intrauterine environment are associated with differential DNA methylation. Given the intense research on the molecular mechanisms of the etiology of obesity and its complications, this review will provide insights into the current understanding of epigenetics and pharmacological and non-pharmacological (such as exercise) interventions targeting epigenetics as they relate to treatment of obesity and its complications. Particular focus will be on DNA methylation, histone modification and non-coding RNAs.

Obesity is associated with chronic inflammation which plays a critical role in the development of cardiovascular dysfunction. Because the adaptor protein caspase recruitment domain-containing protein 9 (CARD9) in macrophages regulates innate immune responses via activation of pro-inflammatory cytokines, we hypothesize that CARD9 mediates the pro-inflammatory signaling associated with obesity en route to myocardial dysfunction. C57BL/6 wild-type (WT) and CARD9(-/-) mice were fed normal diet (ND, 12% fat) or a high fat diet (HFD, 45% fat) for 5months. At the end of 5-month HFD feeding, cardiac function was evaluated using echocardiography. Cardiomyocytes were isolated and contractile properties were measured. Immunofluorescence was performed to detect macrophage infiltration in the heart. Heart tissue homogenates, plasma, and supernatants from isolated macrophages were collected to measure the concentrations of pro-inflammatory cytokines using ELISA kits. Western immunoblotting analyses were performed on heart tissue homogenates and isolated macrophages to explore the underlying signaling mechanism(s). CARD9 knockout alleviated HFD-induced insulin resistance and glucose intolerance, prevented myocardial dysfunction with preserved cardiac fractional shortening and cardiomyocyte contractile properties. CARD9 knockout also significantly decreased the number of infiltrated macrophages in the heart with reduced myocardium-, plasma-, and macrophage-derived cytokines including IL-6, IL-1β and TNFα. Finally, CARD9 knockout abrogated the increase of p38 MAPK phosphorylation, the decrease of LC3BII/LC3BI ratio and the up-regulation of p62 expression in the heart induced by HFD feeding and restored cardiac autophagy signaling. In conclusion, CARD9 knockout ameliorates myocardial dysfunction associated with HFD-induced obesity, potentially through reduction of macrophage infiltration, suppression of p38 MAPK phosphorylation, and preservation of autophagy in the heart.

Insulin resistance leads to myocardial contractile dysfunction and deranged autophagy although the underlying mechanism or targeted therapeutic strategy is still lacking. This study was designed to examine the impact of inhibition of the cytochrome P450 2E1 (CYP2E1) enzyme on myocardial function and mitochondrial autophagy (mitophagy) in an Akt2 knockout model of insulin resistance. Adult wild-type (WT) and Akt2 −/− mice were treated with the CYP2E1 inhibitor diallyl sulfide (100 mg/kg/d, i.p.) for 4 weeks. Cardiac geometry and function were assessed using echocardiographic and IonOptix systems. Western blot analysis was used to evaluate autophagy, mitophagy, inducible NOS (iNOS), and the NLRP3 inflammasome, a multi-protein intracellular pattern recognition receptor complex. Akt2 deletion triggered insulin resistance, compromised cardiac contractile and intracellular Ca 2+ property, mitochondrial ultrastructural damage, elevated O2 – production, as well as suppressed autophagy and mitophagy, accompanied with elevated levels of NLRP3 and iNOS, the effects of which were significantly attenuated or ablated by diallyl sulfide. In vitro studies revealed that the NLRP3 activator nigericin nullified diallyl sulfide-offered benefit against Akt2 knockout on cardiomyocyte mechanical function and mitophagy (using Western blot and colocalization of GFP-LC3 and MitoTracker Red). Moreover, inhibition of iNOS but not mitochondrial ROS production attenuated Akt2 deletion-induced activation of NLRP3, substantiating a role for iNOS-mediated NLRP3 in insulin resistance-induced changes in mitophagy and cardiac dysfunction. In conclusion, these data depict that insulin resistance through CYP2E1 may contribute to the pathogenesis of myopathic changes including myocardial contractile dysfunction, oxidative stress and mitochondrial injury, possibly through activation of iNOS and NLRP3 signaling.

Lipopolysaccharide (LPS), an essential component of the outer membrane of Gram-negative bacteria, plays a pivotal role in myocardial anomalies in sepsis. Recent evidence has depicted a role of Akt in LPS-induced cardiac sequelae although little information is available with regard to the contribution of Akt isoforms in the endotoxin-induced cardiac dysfunction. This study examined the effect of Akt2 knockout on LPS-induced myocardial contractile dysfunction and the underlying mechanism(s) with a focus on TNF receptor-associated factor 6 (TRAF6). Echocardiographic properties and cardiomyocyte contractile function [peak shortening (PS), maximal velocity of shortening/relengthening, time-to-PS, time-to-90% relengthening] were examined in wild-type and Akt2 knockout mice following LPS challenge (4mg/kg, 4h). LPS challenge enlarged LV end systolic diameter, reduced fractional shortening and cardiomyocyte contractile capacity, prolonged TR90, promoted apoptosis, upregulated caspase-3/-12, ubiquitin, and the ubiquitination E3 ligase TRAF6 as well as decreased mitochondrial membrane potential without affecting the levels of TNF-α, toll-like receptor 4 and the mitochondrial protein ALDH2. Although Akt2 knockout failed to affect myocardial function, apoptosis, and ubiquitination, it significantly attenuated or mitigated LPS-induced changes in cardiac contractile and mitochondrial function, apoptosis and ubiquitination but not TRAF6. LPS facilitated ubiquitination, phosphorylation of Akt, GSK3β and p38, the effect of which with the exception of p38 was ablated by Akt2 knockout. TRAF6 inhibitory peptide or RNA silencing significantly attenuated LPS-induced Akt2 ubiquitination, cardiac contractile anomalies and apoptosis. These data collectively suggested that TRAF6 may play a pivotal role in mediating LPS-induced cardiac injury via Akt2 ubiquitination.

Systemic inflammation and localized macrophage infiltration have been implicated in cardiovascular pathologies, including coronary artery disease, carotid atherosclerosis, heart failure, obesity-associated heart dysfunction, and cardiac fibrosis. Inflammation induces macrophage infiltration and activation and release of cytokines and chemokines, causing tissue dysfunction by instigating a positive feedback loop that further propagates inflammation. Cytosolic adaptor caspase recruitment domain family, member 9 (CARD9) is a protein expressed primarily by dendritic cells, neutrophils, and macrophages, in which it mediates cytokine secretion. The purpose of this review is to highlight the role of CARD9 as a potential target in inflammation-related cardiovascular pathologies.

Alcohol intake is associated with myocardial contractile dysfunction and apoptosis although the precise mechanism is unclear. This study was designed to examine the effect of the cytochrome P450 enzyme CYP2E1 inhibition on ethanol-induced cardiac dysfunction. Adult male mice were fed a 4% ethanol liquid or pair-fed control diet for 6weeks. Following 2weeks of diet feeding, a cohort of mice started to receive the CYP2E1 inhibitor diallyl sulfide (100mg/kg/d, i.p.) for the remaining feeding duration. Cardiac function was assessed using echocardiographic and IonOptix systems. Western blot analysis was used to evaluate CYP2E1, heme oxygenase-1 (HO-1), iNOS, the intracellular Ca(2+) regulatory proteins sarco(endo)plasmic reticulum Ca(2+)-ATPase, Na(+)Ca(2+) exchanger and phospholamban, pro-apoptotic protein cleaved caspase-3, Bax, c-Jun-NH(2)-terminal kinase (JNK) and apoptosis signal-regulating kinase (ASK-1). Ethanol led to elevated levels of CYP2E1, iNOS and phospholamban, decreased levels of HO-1 and Na(+)Ca(2+) exchanger, cardiac contractile and intracellular Ca(2+) defects, cardiac fibrosis, overt O(2)(-) production, and apoptosis accompanied with increased phosphorylation of JNK and ASK-1, the effects were significantly attenuated or ablated by diallyl sulfide. Inhibitors of JNK and ASK-1 but not HO-1 inducer or iNOS inhibitor obliterated ethanol-induced cardiomyocyte contractile dysfunction, substantiating a role for JNK and ASK-1 signaling in ethanol-induced myocardial injury. Taken together, these findings suggest that ethanol metabolism through CYP2E1 may contribute to the pathogenesis of alcoholic cardiomyopathy including myocardial contractile dysfunction, oxidative stress and apoptosis, possibly through activation of JNK and ASK-1 signaling.

// Nan Hu 1,2 , Jun Ren 1,2 and Yingmei Zhang 1,2 1 Shanghai Institute of Cardiovascular Diseases, Zhongshan Hospital, Fudan University, Shanghai, China 2 Center for Cardiovascular Research and Alternative Medicine, University of Wyoming College of Health Sciences, Laramie, WY, USA Correspondence to: Yingmei Zhang, email: // Keywords : sucrose, insulin resistance, ALDH2, Sirt3, PGC-1, Pathology Section Received : May 30, 2016 Accepted : July 19, 2016 Published : September 12, 2016 Abstract Insulin resistance contributes to the high prevalence of type 2 diabetes mellitus, leading to cardiac anomalies. Emerging evidence depicts a pivotal role for mitochondrial injury in oxidative metabolism and insulin resistance. Mitochondrial aldehyde dehydrogenase (ALDH2) is one of metabolic enzymes detoxifying aldehydes although its role in insulin resistance remains elusive. This study was designed to evaluate the impact of ALDH2 overexpression on insulin resistance-induced myocardial damage and mechanisms involved with a focus on autophagy. Wild-type (WT) and transgenic mice overexpressing ALDH2 were fed sucrose or starch diet for 8 weeks and cardiac function and intracellular Ca 2+ handling were assessed using echocardiographic and IonOptix systems. Western blot analysis was used to evaluate Akt, heme oxygenase-1 (HO-1), PGC-1α and Sirt-3. Our data revealed that sucrose intake provoked insulin resistance and compromised fractional shortening, cardiomyocyte function and intracellular Ca 2+ handling ( p 0.05), mitochondrial injury (elevated ROS generation, suppressed NAD+ and aconitase activity, p < 0.05 for all), the effect of which was ablated by ALDH2. In vitro incubation of the ALDH2 activator Alda-1, the Sirt3 activator oroxylin A and the histone acetyltransferase inhibitor CPTH2 rescued insulin resistance-induced changes in aconitase activity and cardiomyocyte function ( p < 0.05). Inhibiting Sirt3 deacetylase using 5-amino-2-(4-aminophenyl) benzoxazole negated Alda-1-induced cardioprotective effects. Taken together, our data suggest that ALDH2 serves as an indispensable cardioprotective factor against insulin resistance-induced cardiomyopathy with a mechanism possibly associated with facilitation of the Sirt3-dependent PGC-1α deacetylation.

Diabetic cardiomyopathy is manifested by compromised systolic and diastolic function. This study was designed to examine the role of advanced glycation endproduct (AGE) and AGE receptor (RAGE) in diabetic cardiomyopathy. Heart function was assessed in isolated control and streptozotocin-induced diabetic hearts following in vivo RAGE gene knockdown using RNA interference. Cardiomyocyte mechanical properties were evaluated including peak shortening (PS), time-to-PS (TPS) and time-to-90% relengthening (TR(90)). RAGE was assayed by RT-PCR and immunoblot. Diabetes significantly enhanced cardiac MG, AGE and RAGE levels accompanied with colocalization of AGE and RAGE in cardiomyocytes. Diabetes-elicited increase in RAGE was inhibited by in vivo siRNA interference. The AGE formation inhibitor benfotiamine significantly attenuated diabetes-induced elevation in MG, AGE, RAGE and collagen cross-linking without affecting hypertriglyceridaemia and hypercholesterolaemia in diabetes. Diabetes markedly decreased LV contractility, as evidenced by reduced +/-dP/dt and LV developed pressure (LVDP), which were protected by RAGE gene knockdown. In addition, MG-derived AGE (MG-AGE) up-regulated cardiac RAGE mRNA and triggered cardiomyocyte contractile dysfunction reminiscent of diabetic cardiomyopathy. The MG-AGE-elicited prolongation of TPS and TR(90) was ablated by an anti-RAGE antibody in cardiomyocytes. Interestingly, MG-AGE-induced cardiomyocyte dysfunction was associated with mitochondrial membrane potential (MMP) depolarization and reduced GSK-3beta inactivation in control cardiomyocytes, similar to those from in vivo diabetes. Treatment with siRNA-RAGE ablated diabetes-induced MMP depolarization and GSK-3beta inactivation. Collectively, our result implicated a role of AGE-RAGE in the pathogenesis of diabetic cardiomyopathy.

Circulating insulin-like growth factor-1 (IGF-1) levels are linked to cardiac performance and lifespan. However, the role of IGF-1 levels in aging-associated cardiac dysfunction has not been defined. This study was designed to evaluate the impact of severe liver IGF-1 deficiency (LID) on aging-induced cardiomyocyte contractile and intracellular Ca(++) dysfunction. Cardiomyocytes were isolated from young (2- to 4-month-old) and old (24- to 26-month-old) male C57BL/6 and LID mice. Cardiomyocyte contractile and intracellular Ca(++) transient properties were evaluated, including peak shortening (PS), maximal velocity of shortening/relengthening (+/-dL/dt), time-to-PS (TPS), time-to-90% relengthening (TR(90)), electrically stimulated change in fura-fluorescence intensity (DeltaFFI), and intracellular Ca(++) decay rate. Aged C57BL/6 myocytes displayed reduced PS, +/-dL/dt and DeltaFFI as well as prolonged TR(90) and intracellular Ca(++) decay. IGF-1 deficiency decreased +/-dL/dt, and prolonged TR(90) with little change in other mechanical indices. Interestingly, LID dampened aging-induced changes in cardiomyocyte function. Aging and IGF-1 deficiency both contributed to whole-body glucose intolerance. Aging downregulated expression of Akt, Klotho, and pAMPK, whereas it upregulated p53 expression, the effects of which were cancelled by IGF-1 deficiency. Aging and IGF-1 deficiency significantly reduced expression of the transcriptional factor Foxo3a without an overt effect on the mammalian target of rapamycin (mTOR) level. Collectively, these data depicted that IGF-1 deficiency may reduce the cardiomyocyte sensitivity to aging-induced mechanical dysfunction. Our data suggest that regulation of Akt, p53, adenosine monophosphate-activated protein kinase (AMPK) phosphorylation, and Klotho may play a role, at least in part, in IGF-1 deficiency-induced "desensitization" of cardiac aging.

IGF-I rescues diabetic heart defects and oxidative stress, although the underlying mechanism of action remains poorly understood. This study was designed to delineate the beneficial effects of IGF-I with a focus on RhoA, Akt, and eNOS coupling. Echocardiography was performed in normal or diabetic Friend Virus-B type (FVB) and IGF-I transgenic mice. Cardiomyocyte contractile properties were evaluated using peak shortening (PS), time-to-90% relengthening (TR90), and intracellular Ca2+ rise and decay. Diabetes reduced fraction shortening, PS, and intracellular Ca2+; it increased chamber size, prolonged TR90, and intracellular Ca2+ decay. Levels of RhoA mRNA, active RhoA, and O2− were elevated, whereas nitric oxide (NO) levels were reduced in diabetes. Diabetes-induced O2− accumulation was ablated by the NO synthase (NOS) inhibitor nitro-l-arginine methyl ester (l-NAME), indicating endothelial NOS (eNOS) uncoupling, all of which except heart size were negated by IGF-I. The IGF-I-elicited beneficial effects were mimicked by the Rho kinase inhibitor Y27632 and BH4. Diabetes depressed expression of Kv1.2 and dihydrofolate reductase (DHFR), increased β-myosin heavy-chain expression, stimulated p38 MAPK, and reduced levels of total Akt and phosphorylated Akt/eNOS, all of which with the exception of myosin heavy chain were attenuated by IGF-I. In addition, Y27632 and the eNOS coupler folate abrogated glucose toxicity-induced PS decline, TR90 prolongation, while it increased O2− and decreased NO and Kv1.2 levels. The DHFR inhibitor methotrexate impaired myocyte function, NO/O2− balance, and rescued Y27632-induced cardiac protection. These results revealed that IGF-I benefits diabetic hearts via Rho inhibition and antagonism of diabetes-induced decrease in pAkt, eNOS uncoupling, and K+ channel expression.

Oxidative stress has been speculated to play an essential role in diabetic cardiomyopathy. This study was designed to examine the effect of the antioxidant catalase on diabetes-induced cardiomyocyte dysfunction and the cellular mechanisms involved. Adult wild-type (FVB) and transgenic mice with cardiac-specific overexpression of catalase were made diabetic by a single injection of streptozotocin (STZ, 220 mg/kg; i.p., maintained for two weeks). Cardiomyocyte contractile properties were evaluated including peak shortening (PS), time-to-PS (TPS), time-to-relengthening (TR(90)), maximal velocity of shortening/relengthening (+/-dL/dt), intracellular Ca(2+) level and decay rate. STZ depressed -dL/dt, prolonged TPS and TR(90), elevated resting intracellular Ca(2+) level and reduced intracellular Ca(2+) decay in FVB myocytes. While catalase exhibited little effect on contractile and intracellular Ca(2+) properties in control myocytes, it negated diabetes-induced cardiomyocyte mechanical abnormalities. Diabetic myocytes exhibited enhanced levels of reactive oxygen species and apoptosis, which were alleviated by catalase. Western blot analysis revealed that diabetes reduced Akt phosphorylation, enhanced the silent information regulator 2 (Sirt2), and upregulated Forkhead transcriptional factor Foxo3a as well as glycogen synthase kinase-3beta (GSK-3beta) and pGSK-3beta. While catalase itself exhibited little effect on these proteins or their phosphorylation (with the exception of Sirt2), it significantly attenuated diabetes-induced alteration in pAkt, Foxo3a and Sirt2 without affecting GSK-3beta. Inhibition of Sirt2 using splitomicin impaired cardiomyocyte contractile function (reduced PS, +/-dL/dt, prolonged TPS and TR(90)). In summary, our data suggest potential roles of Akt, Foxo3a and Sirt2 in the onset of diabetic cardiomyopathy and the therapeutic potential of catalase.

Second hand smoke is an independent risk factor for cardiovascular disease. Adiponectin (APN), an adipose-derived adipokine, has been shown to offer cardioprotective effect through an AMPK-dependent manner. This study was designed to evaluate the impact of adiponectin deficiency on second hand smoke-induced cardiac pathology and underlying mechanisms using a mouse model of side-stream smoke exposure. Adult wild-type (WT) and adiponectin knockout (APNKO) mice were placed in a chamber exposed to cigarette smoke for 1 hour daily for 40 days. Echocardiographic, cardiomyocyte function, and intracellular Ca2+ handling were evaluated. Autophagy and apoptosis were examined using western blot. 2',7'-dichlorodihydrofluorescein diacetate (H2DCFDA) staining was used to evaluate reactive oxygen species (ROS) generation. Masson trichrome staining was employed to measure interstitial fibrosis. Our data revealed that adiponectin deficiency provoked smoke exposure-induced cardiomyopathy (compromised fractional shortening, disrupted cardiomyocyte function and intracellular Ca2+ homeostasis, apoptosis and ROS generation). In addition, these detrimental effects of side-stream smoke were accompanied by defective autophagolysosome formation, the effect of which was exacerbated by adiponectin deficiency. Blocking autophagolysosome formation using bafilomycin A1 (BafA1) negated the cardioprotective effect of rapamycin against smoke extract. Induction of autophagy using rapamycin and AMPKα activation using AICAR rescued against smoke extract-induced myopathic anomalies in APNKO mice. Our data suggest that adiponectin serves as an indispensable cardioprotective factor against side-stream smoke exposure-induced myopathic changes possibly through facilitating autophagolysosome formation.

Cardiovascular disease is the most common cause of death in the diabetic population and is currently one of the leading causes of death in the United States and other industrialized countries. The health care expenses associated with cardiovascular disease are staggering, reaching more than 350 billion dollars in 2003. The risk factors for cardiovascular disease include high fat/cholesterol levels, alcoholism, smoking, genetics, environmental factors and hypertension, which are commonly used to gauge an individual's risk of cardiovascular disease and to track their progress during therapy. Most recently, these factors have become important in the early prevention of cardiovascular diseases. Oxidative stress, the imbalance between reactive oxygen species production and breakdown by endogenous antioxidants, has been implicated in the onset and progression of cardiovascular diseases such as congestive heart failure and diabetes-associated heart dysfunction (diabetic cardiomyopathy). Antioxidant therapy has shown promise in preventing the development of diabetic heart complications. This review focuses on recent advances in oxidative stress theory and antioxidant therapy in diabetic cardiomyopathy, with an emphasis on the stress signaling pathways hypothesized to be involved. Many of these stress signaling pathways lead to activation of reactive oxygen species, major players in the development and progression of diabetic cardiomyopathy.

This study characterized the cardiac contractile function and IGF-I response in a transgenic diabetic mouse model. Mechanical properties were evaluated in cardiac myocytes from OVE26 diabetic and FVB wild-type mice, including peak shortening (PS), time to PS (TPS), time to 90% relengthening (TR90) and maximal velocity of shortening/relengthening (±d L/d t). Intracellular Ca2+was evaluated as Ca2+-induced Ca2+release [difference in fura 2 fluorescent intensity (ΔFFI)] and fluorescence decay rate (τ). Sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA)2a, phospholamban (PLB), Na+-Ca2+exchanger (NCX), GLUT4, and the serine-threonine kinase Akt were assessed by Western blot. RhoA and IGF-I/IGF-I receptor mRNA levels were determined by RT-PCR and Northern blot. OVE26 myocytes displayed decreased PS, ±d L/d t, and ΔFFI associated with prolonged TPS, TR90, and τ. SERCA2a, NCX, and Akt activation were reduced, whereas PLB and RhoA were enhanced in OVE26 hearts. GLUT4 was unchanged. IGF-I enhanced PS and ΔFFI in FVB but not OVE26 myocytes. IGF-I mRNA was increased, but IGF-I receptor mRNA was reduced in OVE26 hearts and livers. These results validate diabetic cardiomyopathy in OVE26 mice due to reduced SERCA2, NCX, IGF-I response, and Akt activation associated with enhanced RhoA level, suggesting a therapeutic potential for Akt and RhoA.

Diabetic cardiomyopathy is characterized by impaired ventricular contraction and altered function of insulin-like growth factor I (IGF-I), a key factor for cardiac growth and function. Endogenous IGF-I has been shown to alleviate diabetic cardiomyopathy. This study was designed to evaluate exogenous IGF-I treatment on the development of diabetic cardiomyopathy. Adult rats were divided into four groups: control, control + IGF-I, diabetic, and diabetic + IGF-I. Streptozotocin (STZ; 55 mg/kg) was used to induce experimental diabetes immediately followed by a 7-wk IGF-I (3 mg · kg−1 · day−1 ip) treatment. Mechanical properties were assessed in ventricular myocytes including peak shortening (PS), time-to-PS (TPS), time-to-90% relengthening (TR90) and maximal velocities of shortening/relengthening (±dL/d t). Intracellular Ca2+ transients were evaluated as Ca2+-induced Ca2+ release and Ca2+ clearing constant. Levels of sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA), phospholamban (PLB), and glucose transporter (GLUT4) were assessed by Western blot. STZ caused significant weight loss and elevated blood glucose, demonstrating the diabetic status. The diabetic state is associated with reduced serum IGF-I levels, which were restored by IGF-I treatment. Diabetic myocytes showed reduced PS and ±dL/d t as well as prolonged TPS, TR90, and intracellular Ca2+ clearing compared with control. IGF-I treatment prevented the diabetes-induced abnormalities in PS, ±dL/d t, TR90, and Ca2+ clearing but not TPS. The levels of SERCA and GLUT4, but not PLB, were significantly reduced in diabetic hearts compared with controls. IGF-I treatment restored the diabetes-induced decline in SERCA, whereas it had no effect on GLUT4 and PLB levels. These results suggest that exogenous IGF-I treatment may ameliorate contractile disturbances in cardiomyocytes from diabetic animals and could provide therapeutic potential in the treatment of diabetic cardiomyopathy.

Background Macrophage migration inhibitory factor (MIF) plays a role in the development of obesity and diabetes. However, whether MIF plays a role in fat diet-induced obesity and associated cardiac anomalies still remains unknown. The aim of this study was to examine the impact of MIF knockout on high fat diet-induced obesity, obesity-associated cardiac anomalies and the underlying mechanisms involved with a focus on Akt-mediated autophagy. Methods Adult male wild-type (WT) and MIF knockout (MIF−/−) mice were placed on 45% high fat diet for 5 months. Oxygen consumption, CO2 production, respiratory exchange ratio (RER), locomotor activity, and heat generation were measured using energy calorimeter. Echocardiographic, cardiomyocyte mechanical and intracellular Ca2+ properties were assessed. Apoptosis was examined using TUNEL staining and western blot analysis. Akt signaling pathway and autophagy markers were evaluated. Cardiomyocytes isolated from WT and MIF−/− mice were treated with recombinant mouse MIF (rmMIF). Results High fat diet feeding elicited increased body weight gain, insulin resistance, and caloric disturbance in WT and MIF−/− mice. High fat diet induced unfavorable geometric, contractile and histological changes in the heart, the effects of which were alleviated by MIF knockout. In addition, fat diet-induced cardiac anomalies were associated with Akt activation and autophagy suppression, which were nullified by MIF deficiency. In cardiomyocytes from WT mice, autophagy was inhibited by exogenous rmMIF through Akt activation. In addition, MIF knockout rescued palmitic acid-induced suppression of cardiomyocyte autophagy, the effect of which was nullified by rmMIF. Conclusions These results indicate that MIF knockout preserved obesity-associated cardiac anomalies without affecting fat diet-induced obesity, probably through restoring myocardial autophagy in an Akt-dependent manner. Our findings provide new insights for the role of MIF in obesity and associated cardiac anomalies.

Background Recent evidence has depicted a role of macrophage migration inhibitory factor ( MIF ) in cardiac homeostasis under pathological conditions. This study was designed to evaluate the role of MIF in doxorubicin‐induced cardiomyopathy and the underlying mechanism involved with a focus on autophagy. Methods and Results Wild‐type (WT) and MIF knockout ( MIF −/− ) mice were given saline or doxorubicin (20 mg/kg cumulative, i.p.). A cohort of WT and MIF −/− mice was given rapamycin (6 mg/kg, i.p.) with or without bafilomycin A1 (BafA1, 3 μmol/kg per day, i.p.) for 1 week prior to doxorubicin challenge. To consolidate a role for MIF in the maintenance of cardiac homeostasis following doxorubicin challenge, recombinant mouse MIF ( rmMIF ) was given to MIF −/− mice challenged with or without doxorubicin. Echocardiographic, cardiomyocyte function, and intracellular Ca 2+ handling were evaluated. Autophagy and apoptosis were examined. Mitochondrial morphology and function were examined using transmission electron microscopy, JC ‐1 staining, Mito SOX Red fluorescence, and mitochondrial respiration complex assay. DHE staining was used to evaluate reactive oxygen species (ROS ) generation. MIF knockout exacerbated doxorubicin‐induced mortality and cardiomyopathy (compromised fractional shortening, cardiomyocyte and mitochondrial function, apoptosis, and ROS generation). These detrimental effects of doxorubicin were accompanied by defective autophagolysosome formation, the effect of which was exacerbated by MIF knockout. Rapamycin pretreatment rescued doxorubicin‐induced cardiomyopathy in WT and MIF −/− mice. Blocking autophagolysosome formation using BafA1 negated the cardioprotective effect of rapamycin and rmMIF . Conclusions Our data suggest that MIF serves as an indispensable cardioprotective factor against doxorubicin‐induced cardiomyopathy with an underlying mechanism through facilitating autophagolysosome formation.

Accumulating evidence has indicated that insulin-like growth factor-1 (IGF-1) plays a specific role in the intricate cascade of events of cardiovascular function, in addition to its well established growth-promoting and metabolic effects. IGF-1 is believed to mediate many effects of growth hormone (GH), IGF-1 promotes cardiac growth, improves cardiac contractility, cardiac output, stroke volume, and ejection fraction. In humans, IGF-1 improves cardiac function after myocardial infarction by stimulating contractility and promoting tissue remodeling. Furthermore, IGF-1 facilitates glucose metabolism, lowers insulin levels, increases insulin sensitivity, and improves the lipid profile. These data suggest an attractive therapeutic potential of IGF-1. Both clinically observed and experimentally induced impairments of cardiac function are also found to be associated with abnormal IGF-1 levels. IGF-1 and its binding proteins have been considered as markers for the presence of certain cardiac abnormalities, indicating that IGF-1 may be a risk factor for certain cardiac disorders. The present review will emphasize the role of IGF-1 in the regulation of cardiac growth and function, and the potential pathophysiological role of IGF-1 in cardiac function.

Objective: Antioxidant therapy has shown some promise in critical care medicine in which glutathione depletion and heart failure are often seen in critically ill patients. This study was designed to examine the impact of glutathione depletion and the free radical scavenger, metallothionein (MT), on cardiac function. Design: Friend virus B and MT transgenic mice were given the glutathione synthase inhibitor buthionine sulfoximine (buthionine sulfoximine (BSO), 30 mmol/L) in drinking water for 2 wks. Measurements: Echocardiographic and cardiomyocyte functions were evaluated, including myocardial geometry, fraction shortening, peak shortening, time-to-90% relengthening (TR90), maximal velocity of shortening/relengthening (dL/dt), intracellular Ca 2 rise, sarco- plasmic reticulum Ca 2 release, and intracellular Ca 2 decay rate. Sacro (endo)plasmic reticulum Ca 2 -ATPase function was evaluated by 45 Ca uptake. Highly reactive oxygen species, caspase-3, and aconitase activity were detected by fluorescent probe and colorimet- ric assays. Main Result: BSO elicited lipid peroxidation, protein carbonyl formation, mitochondrial damage, and apoptosis. BSO also re- duced wall thickness, enhanced end systolic diameter, depressed fraction shortening, peak shortening, dL/dt, sarcoplasmic retic- ulum Ca 2 release, 45 Ca uptake, and intracellular Ca 2 decay, leading to prolonged TR90. BSO-induced mitochondrial loss and myofilament aberration. MT transgene itself had little effect on myocardial mechanics and ultrastructure. However, it allevi- ated BSO-induced myocardial functional, morphologic, and carbonyl changes. Western blot analysis showed reduced ex- pression of sacro (endo)plasmic reticulum Ca 2 -ATPase2a, Bcl-2 and phosphorylated GSK-3, enhanced calreticulin, Bax, p53, myosin heavy chain- isozyme switch, and IB phosphor- ylation in FVB-BSO mice, all of which with the exception of p53 were nullified by MT. Conclusion: Our findings suggest a pathologic role of glutathi- one depletion in cardiac dysfunction and the therapeutic potential of antioxidants. (Crit Care Med 2008; 36:2106 -2116)

Catalase, an enzyme which detoxifies H2O2, may interfere with cardiac aging. To test this hypothesis, contractile and intracellular Ca2+ properties were evaluated in cardiomyocytes from young (3-4 months) and old (26-28 months) FVB and transgenic mice with cardiac overexpression of catalase. Contractile indices analyzed included peak shortening (PS), time-to-90% PS (TPS90), time-to-90% relengthening (TR90), half-width duration (HWD), maximal velocity of shortening/relengthening (+/-dL/dt) and intracellular Ca2+ levels or decay rate. Levels of advanced glycation endproduct (AGE), Na+/Ca2+ exchanger (NCX), sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA2a), phospholamban (PLB), myosin heavy chain (MHC), membrane Ca2+ and K+ channels were measured by western blot. Catalase transgene prolonged survival while did not alter myocyte function by itself. Aging depressed+/-dL/dt, prolonged HWD, TR90 and intracellular Ca2+ decay without affecting other indices in FVB myocytes. Aged FVB myocytes exhibited a stepper decline in PS in response to elevated stimulus or a dampened rise in PS in response to elevated extracellular Ca2+ levels. Interestingly, aging-induced defects were nullified or significantly attenuated by catalase. AGE level was elevated by 5-fold in aged FVB compared with young FVB mice, which was reduced by catalase. Expression of SERCA2a, NCX and Kv1.2 K+ channel was significantly reduced although levels of PLB, L-type Ca2+ channel dihydropyridine receptor and beta-MHC isozyme remained unchanged in aged FVB hearts. Catalase restored NCX and Kv1.2 K+ channel but not SERCA2a level in aged mice. In summary, our data suggested that catalase protects cardiomyocytes from aging-induced contractile defect possibly via improved intracellular Ca2+ handling.

Exercise training offers cardioprotection against ischemia and reperfusion (I/R) injury. However, few essential signals have been identified to underscore the protection from injury. In the present study, we hypothesized that exercise-induced acceleration of myocardial tissue oxygenation recovery contributes to this protection. C57BL/6 mice (4 weeks old) were trained on treadmills for 45 min/day at a treading rate of 15 m/min for 8 weeks. At the end of 8-week exercise training, mice underwent 30-min left anterior descending coronary artery occlusion followed by 60-min or 24-h reperfusion. Electron paramagnetic resonance oximetry was performed to measure myocardial tissue oxygenation. Western immunoblotting analyses, gene transfection, and myography were examined. The oximetry study demonstrated that exercise markedly shortened myocardial tissue oxygenation recovery time following reperfusion. Exercise training up-regulated Kir6.1 protein expression (a subunit of ATP-sensitive K(+)channel on vascular smooth muscle cells, VSMC sarc-K(ATP)) and protected the heart from I/R injury. In vivo gene transfer of dominant negative Kir6.1AAA prolonged the recovery time and enlarged infarct size. In addition, transfection of Kir6.1AAA increased the stiffness and reduced the relaxation capacity in the vasculature. Together, our study demonstrated that exercise training up-regulated Kir6.1, improved tissue oxygenation recovery, and protected the heart against I/R injury. This exercise-induced cardioprotective mechanism may provide a potential therapeutic intervention targeting VSMC sarc-K(ATP) channels and reperfusion recovery.

Aims: Chronic alcohol exposure leads to a deficiency of group B vitamins and increased risk of alcoholic cardiomyopathy characterized by impaired ventricular contractility. This study was designed to examine the effect of group B vitamin supplementation on short-term exposure of the main alcohol metabolite acetaldehyde (ACA)-induced cardiac contractile dysfunction in rat ventricular myocytes. Methods: Mechanical contractile properties were evaluated by an IonOptix SoftEdge® system. Protein damage and apoptosis were determined by protein carbonyl and caspase-3 assays, respectively. Results: Short-term (4–6 h) culture of myocytes with ACA (10 μM) depressed peak shortening amplitude, maximal velocity of shortening/relengthening, shortened duration of shortening but not the duration of relengthening. ACA exposure also enhanced protein carbonyl formation and apoptosis in ventricular myocytes. The toxin-induced mechanical defects, protein damage and apoptosis were ablated by vitamin B1 (10 μM), an essential vitamin required for DNA synthesis and repair. Vitamin B6 (10 μM) attenuated ACA-induced impairment of shortening duration. Vitamin B12 (1 mM) attenuated ACA-induced reduction in maximal velocity of shortening/relengthening. Unlike vitamin B1, none of the other ACA-elicited alterations in myocyte mechanical function were affected by vitamin B6 or vitamin B12. Vitamin B6 and vitamin B12 partially, but significantly, attenuated the ACA-induced carbonyl formation without affecting ACA-induced apoptosis. Conclusions: These data provide evidence that vitamin B1 supplementation may be protective for ACA-induced cytotoxicity through protection against protein damage and apoptotic cell death in ventricular myocytes. ( Received 24 March 2004; first review notified 23 April 2004; in revised form 12 May 2004; accepted 25 June 2004 )

Although many aspects of cardiovascular disease are similar between women and men, it is becoming increasingly obvious that there are significant differences as well. Premenopausal women usually have a lower risk of cardiovascular diseases than age-matched men and postmenopausal women. However, the "female advantage" disappears once women are afflicted with diabetes mellitus. Heart diseases are twice as common in diabetic men and five times as common in diabetic women. It is believed that differences in sex hormones and intrinsic myocardial and endothelial functions between men and women may be responsible for this female "advantage" and "disadvantage" in normal and diabetic conditions. Most experimental and clinical studies on diabetes only included male subjects and failed to address this important gender difference in diabetic heart complications. Although female hearts may be better tolerated to stress (such as ischemia) insults than their male counterparts, female sex hormone such as estrogen may interact with certain risk factors under diabetes which may compromise the overall cardiac function. The benefit versus risk of estrogen replacement therapy on cardiac function and overall cardiovascular health in diabetes remains controversial. This review will focus on gender-related difference in diabetic heart complication--diabetic cardiomyopathy--and if gender differences in intrinsic myocardial contraction, polyol pathway metabolism, and advanced glycation endproduct formation and other neuroendocrinal regulatory mechanisms to the heart may contribute to disparity in diabetic cardiomyopathy between men and women.

Diabetes mellitus impairs ventricular function, which itself may be disparately influenced by gender. This study compared the impact of gender on cardiac contractile response in ventricular myocytes from wild-type FVB and calmodulin-induced diabetic transgenic (OVE26) mice at young (2 month) and older (11 month) age. Mechanical and intracellular Ca2+ properties of cardiac myocytes were evaluated using an IonOptix MyoCam system. Diabetic mice of both genders exhibited significantly elevated blood glucose regardless of age. OVE26 myocytes displayed reduced peak shortening (PS) and maximal velocity of shortening/relengthening (+/- dL/dt), and prolonged time-to-PS (TPS) and time-to-90% relengthening (TR90), associated with higher resting intracellular Ca2+ levels and attenuated Ca(2+)-induced intracellular Ca2+ release compared with the FVB myocytes. Peak shortening and +/- dL/dt were smaller in female FVB groups when compared to the age-matched male counterparts. However, these gender differences were ablated by the diabetic state. No significant gender-related differences in intracellular Ca2+ handling were noted in either FVB or OVE26 myocytes, with the exception of overt gender differences in OVE26 mice when age was taken into account. Young female OVE26 mice exhibited better-preserved mechanical function while older female OVE26 mice displayed the worst mechanical function among all four OVE26 groups. In conclusion, our data confirmed impaired cardiac contractile function in diabetes, partially due to altered intracellular Ca2+ handling, in both genders. Mechanical differences existed between genders but were "cancelled off" by diabetic state. Nevertheless, a "female advantage" in ventricular function may still persist in young female diabetic subjects.

Diabetes leads to impaired glucose metabolism and insulin signaling in the heart, which may contribute to the development of diabetic cardiomyopathy. Insulin stimulates tyrosine phosphorylation of the insulin receptor and insulin receptor substrates. A two-fold increase in insulin-stimulated tyrosine phosphorylation has been reported in diabetic myocardium. The aim of the present study was to examine the effect of a putative inhibitor of tyrosine kinase phosphorylation, alpha(2)-Heremans Schmid glycoprotein (AHSG), on the mechanical dysfunction under a simulated diabetic environment.Isolated ventricular myocytes from adult rats were maintained for 24 h in either normal glucose (NG, 5.5 mM) or high glucose (HG, 25.5 mM) medium with 10(-7) M insulin, and in the absence or presence of AHSG (50 micro g/ml). Contractile indices analyzed included: peak shortening (PS), time-to-PS (TPS), time-to-90% relengthening (TR(90)) and area underneath shortening and relengthening (Area/PS).Myocytes maintained in HG medium displayed reduced PS and prolonged TPS/TR(90), with enhanced area, compared to the NG myocytes. Interestingly, these HG-induced mechanical dysfunctions were abolished by AHSG. Removal of insulin from the culture medium did not affect the basal myocyte mechanics, but prevented AHSG from completely protecting against the HG-induced mechanical defects (i.e. HG-induced prolongation of TR(90) and area were only partially attenuated by AHSG in the absence of insulin).The present data support the notion of tyrosine phosphorylation in the pathogenesis of diabetic cardiomyopathy, and implicate the therapeutic value of tyrosine kinase phosphorylation inhibitors.

Diabetes and hypertension both produce myocardial dysfunction that accelerates cardiovascular morbidity and mortality. Coexistence of the two often results in a more severe cardiomyopathy than either process alone. The purpose of this study was to characterize the contractile function of diabetic hypertensive cardiomyopathy at the single myocyte level. Adult spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats were made diabetic with a single injection (55 mg/kg) of streptozotocin (STZ). Contractile properties of ventricular myocytes were evaluated, including peak shortening (PS), time-to-peak shortening (TPS), time-to-90% relengthening (TR90) and maximal velocities of shortening/relengthening (±dL/d t). The experimental animals exhibited enlarged heart size, elevated blood glucose and systolic blood pressure. PS was unchanged (SHR), enhanced (WKY-STZ) or depressed (SHR-STZ) compared to control (WKY). Myocytes from all experimental groups displayed prolonged TPS and TR90compared to the WKY group, although only those from the hypertensive groups (SHR, SHR-STZ) were associated with reduced ±dL/d t. Additionally, myocytes from the WKY-STZ but not the SHR or the SHR-STZ groups exhibited impaired responsiveness to increased extracellular Ca2+. Myocytes from the SHR-STZ group displayed a leftward shift of the stimulus frequency-peak shortening response curve compared to the WKY group. These results confirmed observations at the multicellular levels that combination of diabetes and hypertension results in a greater impairment of cardiac contractile function than is seen with either disease alone.