Search

The present study aimed to explore the protective effect of endogenous sulfur dioxide (SO2) in the development of monocrotaline (MCT)-induced pulmonary hypertension (PH) in rats.Forty Wistar rats were randomly divided into the MCT group receiving MCT treatment, the MCT+L-aspartate-beta- hydroxamate (HDX) group receiving MCT plus HDX treatment, the MCT+SO2 group receiving MCT plus SO2 donor treatment, and the control group. Mean pulmonary artery pressure (mPAP) and structural changes in pulmonary arteries were evaluated. SO2 content, aspartate aminotransferase activity, and gene expression were measured. Superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT), reduced glutathione (GSH), oxidized glutathione, and malondialdehyde (MDA) levels were assayed.In the MCT-treated rats, mPAP and right ventricle/(left ventricle+septum) increased significantly (P0.01), pulmonary vascular structural remodeling developed, and SOD, GSHPx, CAT, GSH, and MDA levels of lung homogenates significantly increased (P0.01) in association with the elevated SO2 content, aspartate aminotransferase activity, and gene expression, compared with the control rats. In the MCT+HDXtreated rats, lung tissues and plasma SO2 content and aspartate aminotransferase activities decreased significantly, whereas the mPAP and pulmonary vascular structural remodeling were markedly aggravated with the decreased SOD, CAT, and GSH levels of lung tissue homogenates compared with the MCT-treated rats (P0.01). In contrast, with the use of a SO2 donor, the pulmonary vascular structural remodeling was obviously lessened with elevated lung tissue SOD, GSH-Px, and MDA content, and plasma SOD, GSH-Px, and CAT levels.Endogenous SO2 might play a protective role in the pathogenesis of MCT-induced PH and promote endogenous antioxidative capacities.

The present study was designed to explore the endogenous production and localization of the sulfur dioxide (SO2)/aspartate aminotransferase pathway in vascular tissues of rats and to examine its vasorelaxant effect on isolated aortic rings,as well as the possible mechanisms.The content of SO2 in the samples was determined by using high performance liquid chromatography with fluorescence detection. Aspartate aminotransferase activity and its gene expression were measured by an enzymatic method and quantitative RT-PCR, respectively. Aspartate aminotransferase mRNA location in aorta was detected by in situ hybridization. The vasorelaxant effect of SO2 on isolated aortic rings of the rats was investigated in vitro. L-type calcium channel blocker, nicardipine, and L-type calcium channel agonist, Bay K8644, were used to explore the mechanisms by which SO2 relaxed the aortic rings.Aorta had the highest SO2 content among the vascular tissues tested (P0.01). The aortic aspartate aminotransferase mRNA located in endothelia and vascular smooth muscle cells beneath the endothelial layer.Furthermore, a physiological dose of the SO2 derivatives (Na2SO3/NaHSO3) relaxed isolated artery rings slightly, whereas higher doses (1-12 mmol/L) relaxed rings in a concentration-dependent manner. Pretreatment with nicardipine eliminated the vasorelaxant response of the norepinephrine-contracted rings to SO2 completely. Incubation with nicardipine or SO2 derivatives successfully prevented vasoconstriction induced by Bay K8644.Endogenous SO2 and its derivatives have a vasorelaxant function, the mechanisms of which might involve the inhibition of the L-type calcium channel.

To explore the possible role of endogenous hydrogen sulfide (H(2)S), a novel gasotransmitter, in the pathogenesis of pulmonary vascular structural remodeling (PVSR) induced by high pulmonary blood flow.Thirty-two Sprague-Dawley male rats were randomly divided into sham, shunt, sham+NaHS (a H(2)S donor) and shunt+NaHS groups. Rats in shunt and shunt+NaHS groups underwent an abdominal aorta-inferior vena cava shunt, and rats in shunt+NaHS and sham+NaHS groups were intraperitoneally injected with NaHS. PVSR was investigated using optical microscope and transmission electron microscope. Lung tissue H(2)S was evaluated by sulfide-sensitive electrodes. Nitric oxide synthase (NOS), heme oxygenase (HO-1), proliferative cell nuclear antigen (PCNA) and extracellular signal-regulated kinase (ERK) activation were analyzed by Western blotting.After 11 weeks of shunting, PVSR developed with a decrease in lung tissue H(2)S production and an increase in nitric oxide (NO). However, lung tissue carbon monoxide (CO) did not change. After the treatment with NaHS for 11 weeks, H(2)S donor ameliorated PVSR and downregulated PCNA expression and ERK activation with an increase in lung tissue CO production and HO-1 protein expression but a decrease in NO production, NOS activity and eNOS protein expression in shunted rats.H(2)S exerted a regulatory effect on PVSR induced by high pulmonary blood flow. Meanwhile, H(2)S down-regulated the ERK/MAPK signal pathway, inhibited the NO/NOS pathway and enhanced the CO/HO pathway in rats with high pulmonary blood flow.

To determine the cardioprotective action of ghrelin and des-octanoyl ghrelin in rats with isoproterenol-induced myocardial injury.Rats were subcutaneously injected with isoproterenol (ISO; 20, 10, and 5 mg/kg) on d 1, 2 and 3, respectively, and then 3 mg/kg for the next 7 d with or without ghrelin or des-octanoyl-ghrelin (100 microg/kg, twice daily). Plasma ghrelin and growth hormone levels were assayed using radioimmunoassay methods. Growth hormone secretagogue receptor (GHSR) and ghrelin mRNA were determined using RT-PCR. The maximal binding capacity and the affinity for [3H]ghrelin were determined by receptor binding assays.Compared with controls, ISO-treated rats showed severe myocardial injury, cardiomegaly, infarction-like necrosis and massive fibrosis with increases in irradiated-ghrelin (ir-ghrelin) content in plasma by 67% and myocardia by 66% and in the mRNA level in the myocardia by 93% (P0.01). ISO-treated rats had 95% (P0.01) higher GHSR mRNA levels in the myocardia. The maximal binding capacity of [3H]ghrelin for myocardial sarcolemma was higher in ISO-treated rats than in controls. Ghrelin administration improved cardiac function and ameliorated cardiomegaly and attenuated myocardial lipid peroxidation injury and relieved cardiac fibrosis as compared with ISO treatment alone. Administration of des-octanoyl ghrelin effectively antagonized ISO-induced myocardial injury and improved all parameters measured. However, the therapeutic effect of des-octanoyl ghrelin was significantly weaker than that of ghrelin. The plasma growth hormone level increased markedly, by 1.5-fold (P0.01), with ghrelin administration as compared with that in controls, but was unaltered in des-octanoyl ghrelin group.Myocardial ghrelin and GHSR were up-regulated during ISO-induced myocardial injury. The protective effect of ghrelin against ISO-induced cardiac function injury and fibrosis was more potent than that of des-octanoyl ghrelin, which suggests that ghrelin could be an endogenous cardioprotective factor in ischemic heart disease, and that its effects include growth hormone-dependent and -independent pathways.

To investigate the role of the endogenous cystathionine gamma-synthase (CSE)/hydrogen sulfide (H2S) pathway in vascular calcification in vivo.A rat vascular calcification model was established by administration of vitamin D3 plus nicotine (VDN). The amount of CSE and osteopontin (OPN) mRNA was determined by using semi-quantitative reverse-transcription polymerase chain reaction. The calcium content, 45Ca2+ accumulation and alkaline phosphatase (ALP) activity were measured. H2S production and CSE activity were measured.von Kossa staining produced strong positive black/brown staining in areas among the elastic fibers of the medial layer in the calcified aorta. The calcium content, 45Ca2+ accumulation and ALP activity in calcified arteries increased by 6.77-, 1.42-, and 1.87-fold, respectively, compared with controls. The expression of the OPN gene was upregulated (P0.01). Expression of the CSE gene was downregulated. However, calcium content, 45Ca2+ uptake and ALP activity in the VDN plus NaHS group was lower than that in the VDN group. The content of calcium and 45Ca2+ accumulation and activity of ALP in the aorta were 34.8%, 40.75% and 63.5% lower in the low-dosage NaHS group than in the VDN group, respectively (P0.01), and the calcium content and deposition of 45Ca2+ and activity of ALP was 83.9%, 37.8 % and 46.2% lower in the aorta in the high-dosage NaHS group than in the VDN group, respectively (P0.01). The expression of the OPN gene was downregulated.The production of H2S, and CSE activity were decreased and CSE gene expression was downregulated in rats with vascular calcification. H2S can ameliorate vascular calcification, suggesting that the H2S/CSE pathway plays a regulatory role in the pathogenesis of vascular calcification.

To investigate effects of taurine on ischemia/reperfusion (I/R)-induced compartment syndrome in rabbit hind limbs.Rabbits underwent femoral artery occlusion after ligation of branches from terminal aorta to femoral artery. After a 7-h ischemia, reperfusion was established with the use of heparinized polyethylene shunts. Rabbits received taurine (1g/kg) or normal saline (control) by iv infusion 10 min before shunt placement. During reperfusion, anterior compartment pressure (ACP) was monitored continuously in the left lower extremity. Gastrocnemius muscle triphenyltetrazolium chloride (TTC) level, taurine content and myeloperoxidase activity were assayed. Oxidative stress was induced in the in vitro gastrocnemius muscle slices by free radical generating systems (FRGS), and the malondialdehyde content was measured in presence or absence of taurine.After 7 h of ischemia, none of the parameters that we measured were different from those before ischemia, except that TTC reduction decreased by 80%. In the control group, after 2 h of reperfusion, ACP increased 4.5-fold, and gastrocnemius muscle taurine content was reduced by 33%. In taurine-treated animals, at 2h reperfusion, the mean arterial blood pressure and heart rate were increased, by 6% and 10%. ACP decreased by 39%, muscle edema decreased by 16%, TTC reduction increased by 150%, and lactate dehydrogenase decreased by 36% compared to control group. Plasma and muscle taurine content increased by 70% and 88%, respectively. In the taurine-treated group, at 2 h reperfusion, plasma malondialdehyde and conjugated diene content were decreased by 38% and 23%, respectively, and muscle malondialdehyde and conjugated diene content decreased by 22% and 30%, respectively compared to the control group. At 2 h reperfusion, myeloperoxidase activity was increased 3.5-fold in control animals. In the in vitro study, taurine decreased malondialdehyde content in muscle slices incubated with hypochlorous acid in a dose-dependent manner, but there was no change when incubated with hydrogen peroxide and xanthine oxidase.Treatment with taurine inhibited I/R-induced compartment syndrome by at least in part attenuating oxidative stress injury induced by I/R, suggesting clinical application of taurine might be a new strategy for the prevention and treatment of compartment syndrome.

To investigate the cardiac protective effects of ghrelin in rat with myocardial injury induced by isoproterenol (ISO).Rats were subcutaneously injected ISO 40 mg/kg/d with or without ghrelin 1 or 10 nmol/kg/d for 2 d. Hemodynamic parameters including mean arterial blood pressure and left ventricular pressure were measured at 12 h after the last injection with ISO and/or ghrelin. Plasma lactate dehydrogenase (LDH) activity, plasma and myocardial contents of malondialdehyde (MDA), and conjugated diene were measured. Plasma ghrelin and endothelin-1 levels were assayed using radioimmunoassay methods. Endothelin-1 and ghrelin mRNA were determined using RT-PCR.About 45 % (5/11) of rats after treatment with ISO alone died during experimental periods. However, no rats died after administration with ghrelin 10 nmol/kg/d (0/11, P0.05). Ghrelin also obviously ameliorated the hemodynamic disturbance in rats induced by ISO. The plasma LDH activity, contents of myocardial and plasma MDA, and conjugated diene level in plasma in ISO+G10 nmol/kg/d group were decreased by 28 %, 34 %, 73 %, and 38 % compared with those of ISO group (all P0.01) respectively. ISO-induced endothelin-1 mRNA over-expression was inhibited and endothelin-1 level in plasma were inhibited by ghrelin 1 and 10 nmol/kg/d. The ghrelin levels in plasma and ghrelin mRNA in myocardium were increased in the rats after injection of ISO. The plasma ghrelin level was further increased after ghrelin administration.Ghrelin has a protective effect against ISO-induced myocardial injury.

To observe protective effects of taurine on reactive oxygen species generation induced by homocysteine in rat vascular smooth muscle cells (VSMC).Rat VSMC was incubated with various concentrations of homocysteine and taurine. The lactate dehydrogenase (LDH) activity which released into culture medium was elevated as an indicator for VSMC injury. The reactive oxygen species (ROS)--hydrogen peroxide (H2O2) and superoxide anion (O2(-*)) were measured with luminol or lucigenin chemiluminescence method, and the mitochondria Mn-superoxide dismutase (Mn-SOD) and catalase (CAT) were also measured in treated VSMC.LDH leakage from cultured VSMC treated with homocysteine, was increased (P0.01 vs control), and it was markedly inhibited when co-incubated with taurine (P0.01). Homocysteine induced H2O2 generation from VSMC in a concentration dependent manner (P0.01 vs control). However, taurine (5, 10, and 20 mmol/L) significantly antagonized 0.5 mmol/L homocysteine-induced H2O2 generation in VSMC in a concentration dependent manner (P0.01 vs homocysteine alone group), although taurine itself did not alter the H2O2 generation in VSMC (P0.05 vs control). In this study, the superoxide anion in VSMC was not detectable by chemiluminescence method. In addition, treatment of VSMC with taurine increased mitochondria Mn-SOD and CAT activity in a concentration dependent manner (P0.05), but homocysteine decreased mitochondria Mn-SOD and CAT activity (P0.01 vs control). In addition, co-administration of taurine markedly ameliorated homocysteine-induced inhibition of Mn-SOD and CAT activity in VSMC (P0.01 vs homocysteine alone group).Taurine antagonized the effects of homocysteine on ROS generation and anti-oxidant enzyme activities in rat VSMC in vitro.

To investigate the role of non N-methyl-D-aspartate acid (non-NMDA) receptors within the caudal ventrolateral medulla (CVLM) in mediating the baroreflex.In urethane-anesthetized, paralyzed, and artificially ventilated rats, the effects of 6-cyano-7-nitroquinoxaline-2,3-dinoe (CNQX, a selective non-NMDA receptors antagonist) locally injected into the CVLM on the depressor responses evoked by aortic nerve stimulation and the barosensitivity of the rostral ventrolateral medulla (RVLM) barosensitive neurons were observed.Bilateral microinjection of CNQX (200 pmol in 100 nL for each side) into the CVLM significantly (P0.01) increased the blood pressure (BP) and heart rate, and markedly (P0.01) attenuated the depressor response to the aortic nerve stimulation. CNQX (200 pmol in 100 nL) unilaterally injected into the CVLM significantly (P0.01) increased the firing rate of the ipsilateral RVLM barosensitive neurons and reduced the inhibitory responses of neurons evoked by stimulation of aortic nerve and elevation of BP, and partially inhibited the neuronal cardiac cycle-related rhythm.The CVLM played an important role in maintaining the tonic excitatory cardiovascular activities and transmitting the baroreceptor information via activation of non-NMDA receptors.

To study the alterations of myocardial taurine transport function, taurine transporter (TAUT), and cysteine sulfinate decarboxylase (CSD) mRNA as well as effect of exogenous taurine in rats with isoproterenol (ISO)-induced cardiomegaly.[3H]-Taurine uptake and release on myocardium were determined. Binding sites of [3H]-taurine for myocardial sarcolemma were measured. TAUT and CSD mRNA levels were assayed using competitive quantitative reverse transcriptase polymerase chain reaction (RT-PCR).ISO group as compared with control group, myocardial taurine uptake markedly reduced, taurine release obviously increased; Bmax value of [3H]-taurine binding on cardiac sarcolemma reduced by 42% (P0.05); TAUT and CSD mRNA levels decreased by 40% and 38% (P0.05), respectively. ISO+taurine group as compared with ISO-treated group, the amounts of taurine uptake and TAUT mRNA returned to normal; taurine release reduced; Bmax increased by 92% (P0.01), and CSD mRNA content augmented by 23% (P0.05). There were no statistical differences of Kd values among the four groups (P0.05).The data indicate that the failure to generate sufficient TAUT on myocardial sarcolemma may be the fundamental abnormality in ISO-induced cardiac injury. The mechanism by which administration of taurine considerably improves ISO-induced cardiac damage is probably to increase the expression of TAUT gene and recover taurine transport function.

To study the role of ghrelin in the late stage of septic shock in rats.The rat model of septic shock was made by caecal ligation and perforation. At the time of operation ghrelin 10 nmol/kg was infused through femoral vein followed by a sc injection at 8 h after operation. Hemodynamic parameters including heart rate (HR), mean arterial blood pressure (MABP), LVdp/dtmax, and left ventricular end-diastolic pressure (LVEDP) in survival rats were measured at 18 h after surgery. Plasma glucose and lactate concentrations, plasma ghrelin level and myocardial ATP content were assayed. The mortality rate in rats with septic shock was also observed.Compared to that of septic shock group, MABP of rats in ghrelin-treated group increased by 33 % (P0.01). The values of +LVdp/dtmax and -LVdp/dtmax increased by 27 % and 33 %, respectively (P0.01), but LVEDP decreased by 33 % (P0.01). The plasma glucose concentration and myocardial ATP content increased by 53 % and 22 %, respectively, but plasma lactate concentration decreased by 40 % in ghrelin-treated rats (P0.01). The plasma ghrelin level in rats with septic shock was 51 % higher than that of rats in sham group, and was negatively correlated with MABP and blood glucose concentration (r=-0.721 and -0.811, respectively, P0.01). The mortality rates were 47 % (9/19) in rats with septic shock and 25 % (3/12) in rats of ghrelin-treated group, respectively.Treatment with ghrelin could correct partly the abnormalities of hemodynamics and metabolic disturbance in septic shock of rats.

To investigate the mechanism by which probucol (PBC) affected adhesion of monocytes to human umbilical vein endothelial cells (HUVEC).Effects of PBC on expression of intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), P-selectin, a nd E-selectin in human umbilical vein endothelial cells were examined. Moreover, the inhibitory effect of PBC were compared with that of monoclonal antibodies (mAbs) to ICAM-1, VCAM-1, P-selectin, and E-select in on adhesion induced by oxidized-low density lipoprotein(Ox-LDL).PBC at 10 to 80 micromol/L inhibited Ox-LD L-induced adhesion index from 16.7 % to 7.0 % (P0.01) and Ox-LDL-induced expression of ICAM-1 (75 %) and P-selectin (72 %). mAbs to ICAM -1 or P-selectin, when used alone, could only slightly reduce the adhesion of monocyte to HUVEC. When both monoclonal antibodies were used in combination, the adhesion was markedly inhibited from 16.7 % to 11.3 % (P0.01), but the effect was still weaker than that of PBC (average 9.3 %).PBC exerts its inhibitory effect on the adhesion of monocyte to HUVEC by inhibiting the expression of ICAM-1 and P-selectin.