The Role Of TRPM7 In Mild Therapeutic Hypothermia (34?) Treated Ischemia Reperfusion Injury Of Myocardium And The Relation With PI3K In A Rat Isolated Heart Model

Objective:To investigate the effect of TRPM7 on the isolated myocardial ischemia reperfusion model in rats treated with mild therapeutic hypothermia at 34?, and to investigate the relationship between TRPM7 and PI3 K pathway in the treatment of mild therapeutic hypothermia at 34?.Methods:One hundred and eight healthy adult male Sprague-Dawley rats(weight250–350g) provided by Hunan SJA Laboratory Animal Co., Ltd were divided into six groups and each group has 6 cases(n=18). SHAM group, do not do any processing; ischemia/reperfusion group(I/R group),with 37? during ischemia for30 min and reperfusion for 120min; ischemai/reperfusion with TRPM7 inhibitor2-APB group(I/R+2-APB group),with the addition of TRPM7 inhibitor 2-APB during reperfusion period; ischemia/ reperfusion with mild therapeutic hypothermia at34 ? group(34H+I/R group),with 34 ? of mild therapeutic hypothermia during reperfusion period; ischemia/reperfusion with mild therapeutic hypothermia and PI3 K inhibitor wortmannin group(34H+I/R+WORT group);with 34? of mild therapeutic hypothermia and the addition of PI3 K inhibitor wortmannin during reperfusion period;ischemia/ reperfusion with mild therapeutic hypothermia and TRPM7 inhibitor2-APB group(34H+I/R+2-APB group),with with 34 ? of mild therapeutic hypothermia and the addition of TRPM7 inhibitor 2-APB during reperfusion period.Then record the hemodynamics including the level of heart rate(HR) ? left ventricular systolic pressure(LVSP) ? left ventricular end-diastolic pressure(LVEDP)?±dp/dtmax(maximum rate and minimal rate of rise of left ventricular) at the time point of baseline, 30 min before ischemia(T0); 30 min after reperfusion(T1);60 min after reperfusion(T2); 90 min after reperfusion(T3); 120 min after reperfusion(T4). At the end of 120 min reperfusion, triphenyltetrazolium chloride staining(TTC) were used to evaluate myocardial infarction size, immuno histochemistry were used to observe the change of TRPM7, western blot were used toinvestigate TRPM7 expression, HE staining was used to observe myocardial injury.Result:1.The expression of TRPM7 in myocardial ischemia reperfusion at 37?(1)In I/R group, the expression of TRPM7 and myocardial infarction size(52.74±1.25%) was significantly increased compared with Sham group(13.87±1.17%,P<0.05);(2)In I/R+2-APB group, the expression of TRPM7 and myocardial infarction size(42.85±1.19%) was decreased compared with Sham group and I/R group(P<0.05);2.The effect of mild therapeutic hypothermia at 34 ? on TRPM7 and its relationship with PI3 K pathway in myocardial ischemia reperfusion injury(1)In 34H+I/R group, the high expression of TRPM7 induced by ischemia reperfusion injury was reversed, the expression of TRPM7 was decreased as well as myocardial infarction size(34.63±0.72%) was decreased compared with I/R group(P<0.05);(2)In 34H+I/R+WORT group, the expression of TRPM7 was increased as well as myocardial infarction size(48.89±0.52%) was increased compared with 34H+I/R group(P<0.05);(3)In 34H+I/R+2-APB group, the expression of TRPM7 was decreased as well as myocardial infarction size(29.75±0.55%) compared with 34H+I/R group and34H+I/R+WORT group(P<0.05).3.There is no significance difference of hemodynamic changes among the groups(P>0.05).Conclusion:1. TRPM7 is highly expressed in myocardial ischemia reperfusion injury in a rat isolated heatr model.2. Mild therapeutic hypothermia at 34 ? can inhibit the high expression of TRPM7 in myocardial ischemia reperfusion, and the protective effect is mediated by PI3 K pathway in a rat isolated heart model.