| Myocardial ischemia is the reduction of hemoperfusion and the myocardial energy metabolism is not normal, which can not support the heart to work.Several pathogenic mechanisms have been proposed to explain the myocardial damage that occurs during myocardial ischemia injury. In recent years, oxidative stress has been shown to play a pivotal role in the pathogenesis of ischemia injury. Apoptosis is the cellular basis in oxidative stress induced by ischemia injury. Mitochondria as oxidative stress sensor and death signal integrator plays a key role in initiating and mediating apoptosis of cardiomyocytes suffered from ischemia damage.Hydrogen sulfide (H2S) is a colorless,water soluble,flammable gas that has the characteristic smell of rotten eggs. Like other members of the gasotransmitter family (nitric oxide and carbon monoxide), H2S has traditionally been considered to be a highly toxic gas and environmental hazard. However, much like for nitric oxide and carbon monoxide, the initial negative perception of H2S has evolved with the discovery that H2S is produced enzymatically in mammals under normal conditions. Endogenous H2S is mainly producted from cysteine and other sulfur-containing amino acids by cystathionine-β-synthase (CBS) and cystathionine-γ-lyase (CSE). It has been shown that H2S plays an important physiological role in diastolic blood vessels, inhibition vascular remodeling and protection of the myocardium. It has also been found that H2S plays a very important role in myocardial ischemia-reperfusion and has a protective effect. The role of H2S in myocardial ischemia has not been previously studied. We therefore investigated the effect of H2S in a rat model of myocardial ischemia in vivo. Part 1 Change of endogenous hydrogen sulfide/cystathionine-γ-lyase system in acute myocardial ischemia ratsObjective: To observe the changes of H2S/CSE system in acute myocardial ischemia rats and to investigate the effect of H2S on acute myocardial ischemia rats.Methods: Eighty male rats were randomly divided into six groups.①sham group;②ischemia 1h group;③ischemia 3h group;④ischemia 6h group;⑤ischemia 9h group;⑥ischemia 12h group. All rats were subjected to openning chest then the left anterior desending coronaries(LADC) were ligated, while the LADC was not ligated in sham group rats. The electrocardiogram(ECG) was recorded under anesthetized condition.The cardiac function indexes such as the left ventricular systolic pressure(LVSP), the left ventricular developed pressure (LVDP), the left ventricular end diastolic pressure (LVEDP),±dp/dtmax were respectively recorded at 1,3,6,9 or 12 hour after ligation.The content of H2S in plasma and the activity of CSE in myocardium were respectively detected. The pathological changes of myocardium were obersved by electron microscope.Results:1 In sham group , the LVEDP, LVDP,±dp/dtmax were not altered from 1 hour to 12 hour after ligating LADC. The LVEDP, LVDP,±dp/dtmax were not altered at 1 hour after ischemia compared with those of sham group(P > 0.05) and the LVDP,±dp/dtmax were significantly decreased and the LVEDP was markedly increased at 3 hour after ischemia compared with those of sham group(P﹤0.05, P﹤0.01), during 6 hour to 12 hour after ligating LADC the cardiac function parameters were significantly altered compared with those of sham group (P < 0.05, P < 0.01).2 In sham group, the content of H2S in plasma and the activity of CSE in myocardium were not altered from 1 hour to 12 hour. The content of H2S in plasma and the activity of CSE in myocardium were not altered at 1 hour after ischemia compared with those of sham group rats ( P > 0.05). The content of H2S in plasma and the activity of CSE in myocardium were significantly decreased at 3 hour after ischemia compared with those of sham group ( P < 0.01). During 6 hour to 12 hour after ischemia, the content of H2S in plasma and the activity of CSE in myocardium were significantly decreased compared with those of sham group (P < 0.05, P < 0.01).3 In sham group, the structure of myocardium were intact. The structure of myocardium were not altered at 1 hour after ischemia compared with that of sham group rats. In ischemia 3 h, 6 h, 9 h and 12 h groups the myocardium were injuried, such as perinuclear cytoplasmic edema, nuclear membrane disappearance myofibrillar fragmentation, mitochondrial cristae and membrane dissolution, disappearance.Conclusion:The content of H2S in plasma and the activity of CSE in myocardium and the structure of myocardium were not altered at 1 hour after ischemia. During 3 hour to 12 hour after myocardial ischemia the content of H2S in plasma and the activity of CSE in myocardium were markedly decreased .It could be concluded that H2S/CSE system may be play a role in the physiopathologic process of acute myocardial ischemia.Part 2 Effects of hydrogen sulfide on the function of mitochondria and apoptosis in acute myocardial ischemia ratsObjective: To study the effect of H2S on acute myocardial ischemia and explore its possible molecular mechanisms from the function of mitochondria and apoptosis in rats.Methods: Fourty male rats were randomly divided into five groups (n=8).①sham group;②ischemia group;③ischemia+NaHS Low dose group;④ischemia +NaHS Middle dose group;⑤ischemia+NaHS High dose group. The left anterior descending coronary was ligatded in ischemia group rats while it was not ligated in sham group rats. In ischemia + NaHS Low (0.78mg/kg),Middle(1.56mg/kg) and High(3.12mg/kg) dose groups rats sodium hydrosulfide (NaHS) were respectively administrated at 3 hour after ischemia. The rats were respectively killed at 6 hour after ischemia. The content of H2S in plasma and the activity of CSE in myocardium were respectively detected. The mitochondria were prepared by differential centrifugation.The swelling and activity of mitochondria were determined. The activities of SOD, GSH-PX and ATPase, and the contents of malondialdehyde (MDA) in myocardial mitochondria were measured. The apoptotic rate of cardiomyocytes was evaluated by Flow Cytometry. The positive expressions of Bcl-2 and Bax in cardiomyocytes were respectively detected by immunohistochemistry.Results:1 The content of H2S in plasma and the activity of CSE in myocardium were significantly decreased in ischemia group rats compared with those of sham group (P < 0.05). Compared with those of ischemia group, the content of H2S in plasma and the activity of CSE in myocardium were significantly increased in ischemia+NaHS Low, Middle and High dose groups (P < 0.05 or P < 0.01).2 In ischemia group, the swelling of mitochondria and the activity of mitochondria were markedly decreased (P﹤0.01) and the activities of SOD, GSH-PX and ATPase were significantly decreased and the content of malondialdehyde (MDA) in myocardial mitochondria was significantly increased(P﹤0.01) compared with those of sham group. In ischemia+NaHS Low, Middle and High dose groups , the activities of SOD, GSH-Px and ATPase and the activity of myocardium mitochondria were significantly enhanced.The swelling of mitochondria was markedly ameliorated and the content of MDA was significantly decreased compared with those of ischemia groups(P < 0.05 or P < 0.01).3 The apoptotic rate of cardiomyocytes and the expression of Bax in ischemia group were significantly increased compared with those of sham group (P<0.01). Compared with those of ischemia group, the apoptotic rates of cardiomyocytes and the expression of Bax were markedly decreased and the expression of Bcl-2 was markedly increased in ischemia +NaHS Low, Middle and High dose groups (P < 0.05 or P < 0.01).4 In sham group , myocardial cells arranged in neat rows and colored evenly. Myocardial fiber striped or disappeared, the nuclear migrated and even cracking disappeared and mang inflammatory cells infiltrates in ischemia group compared with that of sham group. The injury of the myocardium was decreased in NaHS Low, Middle and High dose groups compared with that of ischemia group .Conclusion:It could be concluded that H2S has a beneficial myocardial protection against the ischemia injury in rats by ameliorating the function of myocardium mitochondria, upregulating the expression of Bcl-2,downreg- ulating the expression of Bax. |
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