Effects Of Yangxin Capsule On Myocardial Ischemia And Hemodynamics In Anesthetized Dogs

Objective: The aim of the present study was to investigate the effects of Yangxin capsule(YXC) on acute myocardial ischemia and hemodynamics in anesthetized dogs.Methods: A total of 36 mongrels were divided into six groups, namely sham group, control group, diltiazem treated group, and three YXC treated groups (5,15, and 30 mg ? kg^-1 , respectively ). Myocardial infarction model was established by ligating the left coronary artery at the anterior descending branch in mongrels. The influence of YXC on myocardial infarction size was observed and the ST-segment elevation in ECG was also determined. A blood sample was withdrawn to measure the level of plasma creatine kinase isoenzyme (CK-MB), the activity of superoxide dismutase(SOD) , the content of malondialdehyde (MDA) and nitric oxide(NO), the concentration of plasma endothelin(ET) and sP-selectin. Another 30 healthy aged dogs anesthetized with pentobarbital sodium( 30mg·kg^-1,i.v.)were divided into five groups, namely control group, diltiazem treated group, and three YXC treated groups (5, 15, and 30 mg·kg^-1 , respectively ). The parameters of hemodynamics such as coronary blood flow(CBF), cardiac output(CO), the left ventricular pressure(LVP), the maximum rate of left ventricular pressure( ± dp/dtmax), blood pressure(BP), total peripheral vascular resistance(TPVR), coronary vascular resistance(CVR), oxygen contents of the coronary venous sinus and artery, myocardial oxygen consumption and oxygen utilization rate , left ventricular working index(LVWI), cardiac index and stroke index were detected respectively.Results: YXC significantly diminished myocardial infarction size, reduced the release of CK-MB, protected the activity of SOD, decreased the content of MDA, increased the content of NO and lessen the concentration of plasma ET and sP-selectin(P<0.05 or 0.01) as compared with the control group. Myocardial ischemia degree(∑-ST ) and myocardial ischemia area(N-ST ) were slighter in YXC treated groups than in control group (P<0.05 or 0.01). and after the dogs were administrated with YXC, the diastolic blood pressure(DBP), MVO₂, MVO₂ uptake rate, LVWI, -dp/dt_max, LVEDP and HR were decreased obviously, whereas LVSP, +dp/dt_max, CBF , CVR, CO, CI and SI were not changed significantly.Conclusions: YXC produces a cardio-protective effect during myocardial infarction, which may be related to inhibiting the formation of the oxygen free radical and subsequent peroxidation of lipid, the aggregation and activation of platelet, and improving the function of vascular endothelial cell. YXC could decrease myocardial oxygen consumption by stepping down heart rate , decreasing DBP . YXC could accelerate hemokinesis from epicardium to endocardium by degrading LVEDP.