Inhibitory Effect And Mechanism Of AHV-PI On Platelet Activation In Myocardial Ischemia/Reperfusion Rats

Objective: To investigate the inhibitory effect of platelet inhibitor from Askitrodon halys venom(AHV-PI)on platelet activation in rats with myocardial ischemia / reperfusion injury and its mechanism.Methods: Thirty-six male SD rats were randomly divided into normal control group(NC group),myocardial ischemia/reperfusion injury model group(I/R group),AHV-PI intervention group and BN52021 positive control group(4mg/kg).The AHV-PI experiment group was divided into three groups: low(0.05mg/kg),medium(0.1mg/kg)and high(0.2mg/kg).All rats were divided into 6 experimental groups,6 in each group.The myocardial ischemia-reperfusion injury(MIRI)model was established by ligating the left anterior descending coronary artery of rats for 30 minutes and reperfusion for 2 hours.The AHV-PI experiment group and the BN52021 positive control group were injected intraperitoneally with the corresponding volume of drugs immediately after the ligation of the left anterior descending artery.The normal control group did not duplicate the model,only injected the same volume of normal saline.During the operation,rats were connected with electrocardiogram of ? lead to observe the change of ST segment.Speckle imaging was used to observe the surface blood flow before and after the left anterior descending coronary artery was ligated.TTC staining after surgery to detect myocardial infarction.Blood was collected from the common carotid artery of rats.Four indexes of coagulation were determined by four-channel coagulation analyzer.The contents of creatine kinase(CK)and lactate dehydrogenase(LDH)were measured by colorimetric assay.Turbidimetric method was used to detect platelet aggregation rate.ELISA method was used to detect plasma platelet-activating factor(PAF)content and platelet calcium levels.Results: 1.AHV-PI attenuates myocardial ischemia/reperfusion injury in rats.In the I/R group,the ST segment of the electrocardiogram was significantly elevated,at the same time,the ST segment of AHV-PI middle dose group and AHV-PI high dose group significantly decreased(P<0.01).The myocardium in the I/R group was disorganized by HE staining,and there was a large number of contraction bands.The wavy changes of myocardial fibers were observed.The AHV-PI middle dose group and the AHV-PI high dose group could significantly improve the myocardial cell disorder.The myocardial infarct size in the TTC-stained I/R group was significantly increased.The AHV-PI middle-dose group and the high-dose AHV-PI group significantly reduced the I/R-induced myocardial infarct size(P<0.01).Compared with the I/R group,AHV-PI high-dose group can significantly reduce the activity of LDH and CK(P<0.01).2.AHV-PI significantly inhibited the increase of platelet activation in ischemia/reperfusion rats.AHV-PI medium-dose group and high-dose AHV-PI group could significantly inhibit I/R-induced platelet aggregation rate significantly(P<0.01),prolong APTT,PT,TT time(P<0.05),and reduce FIB content(P<0.05).3.AHV-PI reduces the increase of PAF in ischemia/reperfusion rats.PAF content in I/R group increased significantly(P<0.01).PAF levels in AHV-PI middle-dose group and AHV-PI high-dose group significantly decreased compared with I/R group(P<0.01).4.AHV-PI inhibited the increase of calcium in platelets of ischemia/reperfusion rats.In the I/R group,the intracellular calcium levels in the platelets were significantly increased(P<0.01).The calcium ion in the AHV-PI middle dose group and the AHV-PI high dose group could significantly reduce the I/R-induced calcium ion elevation(P< 0.05).Conclusion: 1.Increased release of platelet-activating factor in myocardial ischemia / reperfusion rats is one of the important factors that cause myocardial injury.2.AHV-PI can inhibit the secretion and release of PAF,reduce the level of calcium in platelet cytoplasm and alleviate myocardial damage in reperfusion rats.