Abstract: AIM: To investigate the clinical significance of plasma levels of protein C(PC) and platelet aggregation in rats with myocardial ischemia and reperfusion injury.METHODS: 40 male SD rats were randomly divided into groups of control (C,n=8),ischemia(I,n=24) and ischemia-reperfusion(IR,n=8). The ischemia groups were divided into 10 min (I₁₀),30 min (I₃₀) and 60 min group(I₆₀) respectively, 8 rats in each group. The rat model of myocardial ischemia and reperfusion was prepared by the left anterior descending coronary artery reversible occlusion. Blood samples were collected from the carotid artery immediately. The plasma PC activity and platelet aggregation were detected by chromogenic substrate assay and turbidity assay, respectively. RESULTS: Plasma PC activities in myocardial ischemia rats were significantly lower than those in the control (P<0.05),and there is a negative relation between the decrease of PC activity and ischemia time;plasma PC activities in ischemia-reperfusion rats were slightly recovered, but still lower than those in the control (P<0.01). The platelet aggregation in ischemia 10 min,30 min ischemia and IR rats were significantly higher than those in the control (P<0.01), while ischemia 60 min platelet aggregation showed no statistical significance compared with the control group.CONCLUSION: Myocardial ischemia and reperfusion injury can result in PC activities loss. These suggest that the decrease of PC activity may be involved in myocardial ischemia and injury, more sensitive than platelet aggregation. Therefore, the PC activity maybe a predictive indicator for ischemic cardiovascular disease.

Key words: Protein C, Myocardial ischemia and reperfusion injury, Platelet aggregation