RESUMO
ObjectiveTo evaluate the role of Janus kinase 2/signal transducer and activator of transcription 3 (JAK2/STAT3) signaling pathway in attenuation of myocardial ischemia-reperfusion (I/R) injury by tetramethylpyrazine in rats.MethodsSixty-four healthy male Wistar rats weighing 250-300 g were randomly divided into 4 groups( n ＝ 16 each):sham operation group (group S),myocardial I/R group(group I/R),teramethylpyrazine group (group T) and AG,490( a JAK2 inhibitor) group (group AG).Myocardial I/R was induced by 30 min occlusion of left anterior desecending coronary artery (LAD) followed by 120 min reperfusion in groups I/R,T and A.In groups T and A teramethylpyrazine 20 mg/kg was injected iv 20 min before LAD occlusion.In group A AG490 3 tμg/g was injected iv at 5 min before reperfusion.Blood samples were then taken from inferior vena cava at 120 min of reperfusion for measurement of serum creatine phosphokinase (CK) and lactose dehydrogenase (LDH) activities.Myocardial infarct size was then measured and myocardial tissue was obtained for microscopic examination.ResultsSerum CK and LDH activities were significantly higher in group I/R than in group S.Pretreatment with tetramethylpyrazine significantly decreased myocardial infarct size and I/R-induced increase in serum CK and LDH activities and histologic damage.The protective effect of tetramethylpyrazine against myocardial 1/R injury was attenuated by postconditioning with AG490.ConclusionJAK2/STAT3 signaling pathway is involved in attenuation of myocardial I/R injury by tetramethyl pyrazine in rats.