Time-course Study On Cardiomyocyte Autophagy In Rats With Early Pressure Overload

Objective:Cardiomyocyte autophagy plays an important role in maintaining normal cardiac structure and function.We and other previous studies have shown that in the model of stress overload induced cardiac hypertrophy and heart failure in mice,in the heart failure period,myocardial fine autophagy increased significantly,increased cardiomyocyte autophagy and myocardial cell apoptosis and decreased cardiac function The However,changes in autophagy of cardiomyocytes have not been fully elucidated in the early stage of stress overload induced cardiac hypertrophy.This study was to investigate the changes of autophagy of cardiomyocytes and their relationship with cardiac hypertrophy in the rat model of abdominal aortic coarctation induced overload.Methods:1.Animal experimental model: Body weight 180-200 g male SD rats underwent abdominal aortic coarctation(Adominal),and the establishment of sham sham group.The rats were sacrificed at 1h,3h,6h,24 h,48h and 72 h after operation.2.Groups:(1).AAC group of 30,respectively,at 1h,3h,6h,24 h,48h,72 h at different time points to kill five;(2)Sham operation group(sham)10,respectively,at 6h,72 h at two time points each killed 5.3.Cardiac hypertrophy and cardiomyocyte autophagy parameters: cardiac weight and body weight ratio(HW / BW,cardiac weight index),left ventricular weight and body weight ratio(LVW / BW,left ventricular weight index)were used to assess cardiac hypertrophy;Morphological changes of cardiomyocytes were observed by hematoxylineosin staining;Western blot was used to detect the expression of autophagy-related proteins in myocardium.Results:Compared with sham operation,the cardiac weight and left ventricular weight index did not change significantly at AAC 1h and 3h after AAC.At 6h after AAC,the ratio of HW / BW increased slightly.At the end of AAC,the HW / BW ratio and LVW /BW ratio increased further,and increased significantly at 48 h and 72 h.AAC group 72 h compared with sham group was statistically significant.Hematoxylin staining showed that the diameter of cardiomyocytes in AAC group was larger than that in Sham group at72 h.The results of immunoblotting showed that the ratio of LC3 II / I,Beclin1 and Atg12 were significantly decreased in AAC group and cardiomyocyte compared with sham operation group.Conclusion:In the early stage of stress overload,autophagy of cardiac cardiomyocytes in rats was decreased.Myocardial cell autophagy is associated with cardiac hypertrophy.It is suggested that cardiomyocyte autophagy inducer may be beneficial to the prevention and treatment of cardiac hypertrophy in the early stage of stress overload induced cardiac hypertrophy.