| Myocardial ischemia injury and the secondary arrhythmia, systolicfunction impairment are the reasons of various clinical types of coronaryatherosclerosis heart disease patients with hemodynamic instability,circulation failure, and even death. But after myocardial ischemia, themechanism of injury and resistance, is not yet fully understood. In recent years,as following the nitric oxide(NO) and carbon monoxide(CO) the third kind ofimportant chemical neurotransmitter and intracellular signalingmolecule-hydrogen sulfide (H2S),is mainly producted from l-cysteine andcystathionine-γ-lyase (CSE) within the mammalian circulatory system. It hasbeen shown that endogenous H2S can inhibit inflammation, reduce calciumoverload and cell apoptosis, protect mitochondria and other kinds of ways toreduce myocardial infarction area, save the survival myocardium, restorecardiac function, and can inhibit vascular smooth muscle cell proliferation,reverse vascular remodeling, promote restoration of the damaged endothelialcells. However, its relationship with the pathogenesis of cardiovasculardisease remains to be further studied. In the present experiment, we observedthe changes of H2S/CSE system in acute myocardial ischemia,and the effect ofH2S on myocardial ischemia injury and explored the possible mechanisms.Part1Change of endogenous hydrogen sulfide(H2S)/cystathionine-γ-lyase (CSE) in isolated ischemic heartsObjective: To observe the changes of H2S/CSE in isolated ischemichearts in rats.Methods:160male SD rats, weighing250-300g, were randomly dividedinto six groups.①sham group(n=80),②ischemia30min group(n=16),③ischemia1h group(n=16),④ischemia2h group(n=16),⑤ischemia3h group(n=16),⑥ischemia4h group(n=16). The rats in the sham group wereonly threaded without ligation, and the left anterior descending coronary arterywas ligated in rats of the ischemia group. The hemodynamic parameters, suchas the left ventricular developed pressure (LVDP),±dp/dtmaxand coronaryarterial flow(CF) were respectively recorded to evaluate the cardiac function.The content of H2S and the activity of CSE in cardiac tissue were respectivelydetermined. The infarct volumes of hearts were determined by dual stainingwith Evans-blue and TTC. Ischemic myocardial tissue area and volume wereobserved and calculated by image analysis system.Results:1There were no statistically differences in baseline cardiodynamic dataamong the experimental groups. Compared with those of the sham group,LVDP,±dp/dtmaxand CF were significantly decreased at30min、1h、2h、3h、4h after ischemia(P<0.01).2There were no statistically differences in the content of H2S and theactivity of CSE in cardiac tissue in the sham group from30min to4h afterstabilization. Compared with those of the sham group, there were nostatistically differences in the content of H2S and the activity of CSE incardiac tissue at30min after ischemia. However, during1h to4h afterischemia, the content of H2S and the activity of CSE in cardiac tissue weresignificantly decreased compared with those of the sham group(P<0.05orP<0.01).3Compared with those of the sham group, the infarct volumes weregreatly increased at1h to4h after ischemia (P<0.01).Conclusion: After ischemia for2h, the content of H2S and the activity ofCSE in cardiac tissue were significantly decreased with larger infarct volumes.It could be concluded that H2S and CSE were involved in myocardial ischemiainjury in isolated hearts in rats.Part2Effects of Hydrogen Sulfide on Myocardial Ischemia mitochondrialInjury in RatsObjective: To study the effect of H2S on myocardial ischemia and explore its possible mechanisms from the function of mitochondria in rats.Methods: Eighty male SD rats, weighing250-300g, were randomlydivided into five groups.①sham group(n=16),②model group(n=16),③lowdose group of NaHS(n=16),④middle dose group of NaHS(n=16),⑤high dosegroup of NaHS(n=16). The rats in the sham group were only threaded withoutligation, and the left anterior descending coronary artery was ligated in rats ofthe ischemia group. The normal perfusate was replaced with NaHS perfusate（5μmol/L，10μmol/L，20μmol/L）accordingly in low dose group of NaHS,middle dose group of NaHS and high dose group of NaHS at2h afterischemia. The left ventricular developed pressure (LVDP),±dp/dtmaxandcoronary arterial flow(CF) were respectively recorded to evaluate the cardiacfunction. The content of H2S and the activity of CSE in cardiac tissue wererespectively determined at4h after ischemia. The infarcted volume of thehearts in each group rats were observed and calculated by image analysissystem. The ultrastructural alterations of myocardium were observed byelectric microscope. The mitochondria were prepared by differentialcentrifugation. The swelling and activity of mitochondria were determined.The activities of ATPase， GSH-PXand SOD， and the contents ofmalondialdehyde (MDA) in myocardial mitochondria were respectivelymeasured.Results:1Compared with those of the sham group, LVDP,±dp/dtmax and CFwere significantly decreased in model group (P<0.01). Compared with thoseof the model group, LVDP,±dp/dtmaxand CF were significantly increased inNaHS low, middle and high dose groups (P<0.05or P<0.01).2Compared with those of the sham group, the content of H2S and theactivity of CSE in cardiac tissue were significantly decreased in model group(P<0.01).Compared with those of the model group, the content of H2S andthe activity of CSE in cardiac tissue were significantly increased in NaHS low,middle and high dose groups (P<0.05or P<0.01).3Compared with those of the sham group, the infarct volumes was significantly increased in model group(P<0.01). Compared with those of themodel group, the infarct volumes was significantly decreased in NaHS middleand high dose groups (P<0.01).4The ultrastructure of the myocardial cells exhibited regularmitochondria with uniform size, complete mitochondrial cristae, and intactnuclear membrane in the sham group,however,the myocardial cells werecharacterized by mitochondrial swelling, disappearance or deformation ofmitochondrial cristae, disruption of nuclear membrane, and nuclearcondensation in the model group. Compared with those of the model group,thepathological change in myofilaments, mitochondria and nucleus weresignificantly decreased in NaHS low, middle and high dose groups.5Compared with those of the sham group, the swelling of mitochondriawas markedly increased and the activity of mitochondria was significantlydecreased (P﹤0.01) and the activities of SOD, GSH-PXand ATPase weresignificantly decreased and the content of malondialdehyde (MDA) inmyocardial mitochondria was significantly increased(P﹤0.01) in model group.Compared with those of the model group, the activities of SOD, GSH-Px andATPase and the activity of myocardium mitochondria were significantlyenhanced(P <0.05or P <0.01),the mitochondria swelling was significantlyameliorated and the content of MDA was significantly decreased(P﹤0.01) inNaHS low, middle and high dose groups.Conclusion: It could be concluded that H2S has a beneficial ischemiatissue protection against the ischemia injury in rats by improving the functionof myocardial mitochondria, antagonizing oxidative stress in myocardialmitochondria and protecting mitochondrial structure and redox function,which may be one of the mechanisms of ameliorating ischemia injury. |
PDF Full Text Request