Effect of autophagy and mitochondrial coenzyme Q on cardiac function of rats with acute sepsis / 中华实用儿科临床杂志

ABSTRACT

Objective To investigate the effects of autophagy on cardiac function and to determine whether the mitochondrial coenzyme Q (MitoQ) prevents cardiac dysfunction,mediated by autophagy,in rats with acute sepsis.Methods Forty-five Sprague Dawley (SD) rats were randomly divided into 9 groups (n =5,each group)control group,4 h lipopolysaccharide(LPS) group,6 h LPS group,12 h LPS group,4 h LPS + Wortmannin group,4 h LPS + MitoQ group,6 h LPS + MitoQ group,MitoQ group and Wortmannin group.Rats in LPS + Wortmannin group and LPS + MitoQ group were intraperitoneally given LPS(10 mg/kg) and followed by an injection of Wortmannin(2 mg/kg) and MitoQ (6.5 μmol/kg) via tail vein 1 hour later,respectively.Rats in each group were given the same amount of normal sodium in addition to different intervention drugs.The cardiac function parameters were measured by a BL-420E + biosignal collection system.Blood samples from abdominal aorta were taken at each time point,and creatine kinase MB isoenzyme (CK-MB) content was detected by using the velocity method.The content of reactive oxygen species (ROS) in isolated myocardial tissues in rats was measured by enzyme-linked immunoadsorbent assay(ELISA).The protein expression of microtubule-associated protein 1 light chain 3 (LC3) was detected by Western blot method.The pathological changes of myocardial tissue were observed by light and electronic microscopy.Results Compared with the control group,the left ventricular systolic pressure(LVSP),the rate of the rise in left ventricular pressure (± dp/dt max) were significantly decreased in 6 h LPS group,6 h LPS + MitoQ group and 4 h LPS + Wortmannin group(P ＜0.05),left ventricular end-diastolic pressure(LVEDP) was significantly increased in these 3 groups(P ＜0.05).The contents of CKMB and ROS in 6 h LPS group,6 h LPS =MitoQ group and 4 h LPS + Wortmannin group were higher than those in the control group(P ＜ 0.05).Electron microscopy showed that the number of autophagic vacuoles increased 6 h after LPS was administered,but did not increase significantly thereafter to 12 h.There was no difference at any time point in the number of autophagic vacuoles in the group given MitoQ and LPS.Immunoblotting demonstrated that the levels of LC3Ⅱ protein in the LPS 6 h group and LPS + MitoQ 6 h group were higher than those in the control group(P ＜0.05),but there was no difference between the LPS 12 h and LPS 6 h groups (P ＞ 0.05).Conclusions The mitochondria-targeted antioxidant MitoQ does not prevent cardiac dysfunction.However,autophagy prevents cardiac dysfunction,and the autophagic capacity or autophagosome-formation rate may determine whether cardiac dysfunction develops.