The Experimental Study Of Myocardial Ischemia And Reperfusion Injury And Pharmocologic Protection

1. The in vivo porcine heart ischemia reperfusion OR) model: We used porcine heart for the establishment of experimental model, since both human and porcine hearts contain undetectable amounts of xanthine oxidase and have the similar distribution of coronary arteries.The results show:(1) During 45 min occlusion and 5-6 hour reperfusion of left anterior descending coronary artery (LADA), animal blood pressure, heart rate and body temperature were stable.(2) The proximal and distal portion of the occluded site of LADA were approximitely 2 : 3 proportions. The variaties of myocardial infarct size (MIS) were small, and average MIS was 2d.(?)± 4.1 % of the left ventricular weight.(3) Incidences of ventricular fibrillation (VF), ventricullar tachycardia (VT) and ventricular premature beat (VPB) of ischemia were similar to reperfusion. Incidence of no paroxysmal ventricular tachycardia (NPYT) of reperfusion was higher than ischemia.2. The results of the study of mechanisms of IR injury:(1) [Na⁺],and [Ca²⁺],significantly increased and (K⁺-declined. This demonstrates that Ca²⁺overload exists in vivo model, which indirectly indicates that pertubation of ion transport systems, especially Na⁺,K⁺—ATPase and Na⁺—Ca₂₊exchange are primarily responsible for the increased influx of Ca²⁺upon reperfusion.(2) Alteraton of chemoluminescense of serum and myocardial cellular memberane fluidity indirectly demonstrated that free radical increased after reperfusion and free radical initiated lipid peroxidation and altered the function and structure of cells. The results support the hypothesis that free radicals may...