Levosimendan attenuates suspension-reperfusion injury in isolated hearts of rat models
Objective To investigate the effect of levosimendan on the cyclic guanosine monophosphate-adenosin monophosphate synthase-interferon gene stimulating factor(cGAS-STING)signaling pathway during suspension-reperfusion in isolated rat myocardium.Methods The rats were divided into four groups(n=12)using random number table:continuous perfusion group(CO group),suspension-reperfusion group(SR group),suspension-reper-fusion+levosimendan group(SR-L group),and suspension-reperfusion+levosimendan+STING activator:DMXAA group(SR-LD group).Heart rate(HR),left ventricular end-diastolic pressure(LVEDP),left ventricular develop-mental pressure(LVDP),maximum rate of increase in left ventricular pressure(+dp/dtmax)and maximum rate of decrease in left ventricular pressure(-dp/dtmax),and Reperfusion Arrhythmia scores were recorded at the end of equilibrium perfusion(T0),30 min of reperfusion(T1),and 60 min of reperfusion(T2)respectively.Western blot was used to detect cGAS-STING signaling pathway and autophagy-related protein expression.The size of myocardial infarction was measured by using triphenyl tetrazolium chloride(TTC).Results Compared with CO group,SR group had decreased HR,LVDP,+dp/dtmax,and-dp/dtmax at T1 and T2,increase of LVEDP,Reperfusion Arrhythmia score,percentage of myocardial infarcted area,expression of myocardial tissue cGAS and STING pro-teins and increased LC3 Ⅱ/Ⅰratio,while p62 decreased(P<0.05);compared with SR group,SR-L group car-diac function indexes improved,myocardial tissue cGAS,STING protein expression was down-regulated,LC3 Ⅱ/Ⅰ ratio was decreased,and p62 was elevated(P<0.05);SR-LD group reversed the improvement of myocardial injury by levosimendan compared with SR-L.Conclusions Levosimendan may protect myocardial tissue by inhibi-ting the cGAS-STING signaling pathway,down-regulating cardiomyocyte autophagy and reducing myocardial infarc-tion size,so to improve cardial function.