Objective To investigate the changes of endothelial function during myocardial ischemia and reperfusion (I/R) injury of rabbits, and the protection of ShenFu injection (SFI) for the injury, as well as the related mechanism. Methods Twenty one Japanese white rabbits were randomly divided into 3 groups (7 each): sham operated group (A), I/R group (B) and SFI-treated I/R group (C). The activity of serum endothelial nitric oxide synthase(eNOS), the concentrations of serum nitric oxide products (NOP) and plasma endothelin (ET) before ligation of coronary artery, 40min after ischemia and 40min after reperfusion were determined. The concentration of total superoxide dismutase (T-SOD) and malonyl-dialdehyde (MDA) in myocardial tissue were determined. Ultrastructure of myocardial cell was observed by electro microscope. Results 1) Serum eNOS and NOP decreased and plasma ET increased ingroup B than that ingroup A after 40min of ischemia (P<0.01), even more significant after 40min of reperfusion. NOP was correlated positively with ETafter 40min of ischemia (P<0. 05) and after 40min of reperfusion ( P<0. 01). In 40min after reperfusion, T-SOD was decreased and MDA was increased ingroup B than that in group A, significantly (P<0. 01). NOP were correlated positively with T-SOD, while were correlated negatively with MDA (P<0.05). ET was correlated positively with MDA, while was correlated negatively with T-SOD (P<0.05). Ultrastructure of myocardial cell changed abnormally. 2) SFI can increase eNOS and NOP after 40min ischemia and 40min reperfusion, and decrease ET after 40min reperfusion, significantly (P<0. 01). SFI can increase T-SOD and decrease MDA significantly (P<0. 01), the abnormality of myocardial cells can be relieved obviously. Conclusion SFI can improve the endothelial function in which free radicals are involved, and prevent myocardial tissue from I/R injury.

BACKGROUND: With the extensive development of reperfusion treatment on acute myocardial infarction, myocardial ischemia/reperfusion (I/R) injury cause clinical concern intensively. In recent years, nitric oxide (NO) and endothelin (ET)are hot point of researches. Myocardial protective role of Chinese traditional medicine is highly regarded.OBJECTIVE: To study the change of endothelial function during myocardial I/R injury of rabbits, the effect of shenmai injection (SMI) and mechanism.DESIGN: Randomized controlled animal study.SETTING: The First Hospital Affiliated to China Medical University.MATERIALS: The experiment was carried out in Laboratory Animal Center, Department of Biochemistry and the Second Electron Microscope Room of China Medical University from September 2002 to January 2003. Twenty-one healthy female Japanese white rabbits weighing 1.5-2.5 kg were in this study. SMI was produced by the Three Nine Medicine Industry Co., Ltd., Yaan (batch number: 010110).METHODS: ① Grouping: The animals were randomly divided into three groups, 7 cases of each group. Sham-operation group: Rabbits were gone through thread only and were not ligated coronary artery; I/R group and I/R + SMI group:Coronary artery occlusion was maintained 40 minutes at the ligature was released and reperfusion continued for 40 minutes. ② Administration: Rabbits in I/R group were injected 20 mL saline through ear margin vein (injected one third of saline at 10 minutes before ligature, two thirds of saline when unloosing the ligature). Rabbits in I/R + SMI group were injected with SMI which was diluted with saline to 20 mL (1.5 mL/kg). The method of injection was as same as I/R group.③ Index observation: 4 mL venous blood samples were obtained before ligature, at 40 minutes of ischemia and 40minutes of reperfusion. Half of the blood samples were separated serum to detect NO production (NOP) by nitric acid deacidizing enzyme process; another were separated plasma to detect ET by radiation immunity process. In the experiment ends, NOP and ET of myocardial tissue were detected; total of superoxide dismutase (T-SOD) of myocardial tissue were detected by sulphur purine oxidase process and malondialdehyde (MDA) were detected by thiobarbituric acid development process. Myocardial ultrastructure was observed with transmission electro microscope.MAIN OUTCOME MEASURES: ① Contents of serum NO and plasma ET in each.group before ligature, at 40 minutes of ischemia and 40 minutes of reperfusion; ② contents of NOP, ET, T-SOD and MDA of myocardial tissue; ③ Myocardial ultrastructure.RESULTS: All 21 rabbits were involved in the final analysis. ① Content of serum NOP: Content of serum NOP was lower in I/R group than that in sham-operation group at 40-minute ischemia and 40-minute perfusion (P ＜ 0.01), but was higher in I/R +SMI group than that in I/R group (P＜ 0.01). ② Content of plasma ET: Content of plasma ET was higher in I/R group than that in sham-operation group at 40-minute ischemia and 40-minute perfusion (P ＜ 0.01), but was lower in I/R +SMI group than that in I/R group (P ＜ 0.01). ③ Content of NOP was negative correlation with that of ET 40-minute ischemia and 40-minute perfusion (P ＜ 0.05, P ＜ 0.01). ④ Content of NOP and activity of T-SOD: Those were lower in I/R group than those in sham-operation group at 40-minute perfusion (P ＜ 0.01), but were higher in I/R +SMI group than those in I/R group (P＜ 0.01). ⑤ Contents of ET and MDA: Those were higher in I/R group than those in sham-operation group (P ＜ 0.01), but were lower in I/R +SMI group than those in I/R group (P ＜ 0.01). ⑥ Content of NOP was positive correlation with T-SOD activity (P ＜ 0.05), and negative correlation with content of MDA (P ＜ 0.05). In addition, content of ET was negative correlation with T-SOD activity (P ＜ 0.05), and positive correlation with content of MDA (P ＜ 0.05).CONCLUSION: Myocardial I/R leads to abnormality of vascular endothelial function, and SMI can improve endotheliual function and relieve myocardial I/R injury.