Preventing effect of L-carnitine on Iso-induced myocardial hypertrophy and its mechanism

Aim To investigate the potential effect of L-carnitine in myocardial hypertrophy induced by Isoproterenol(Iso) in rats and to explore the cardio protective mechanism.Methods The model of myocardial hypertrophy induced by Iso in SD rats was adopted.Forty male rats were randomly divided into four groups: control group,Iso group,Iso+L-carnitine group(L-carnitine group) and Iso+propranolol(propranolol group),with 10 rats each group.All except normal control group were made into myocardial hypertrophy by subcutaneous injection of Iso and each group was raised 8 weeks.The tissue of heart was taken to detect calculated heart mass index(HMI)and left ventricular mass index(LVMI).The left ventricle myocardium sections were made for Masson dying and were examined by light microscope.The free fatty acids(FFA),lactic acid(LAC) and hydroxyproline(Hpy) were measured.Cardiac cells were isolated to measure the mitochondrial membrane potential.Results Compared with Iso group,the heart function,ratio of ventricle weight to heart weight and ratio of heart weight to body weight of L-carnitine group reduced significantly.Results of optical microscope:the level of myocyte hypertrophy was much lower in L-carnitine group,and cells arranged in a good order,collagen fiber proliferated in low level.The lactic acid,free fatty acid and hydroxyproline levels were significantly decreased by L-carnitine.The expression of mitochondrial membrane potential was effectively increased by L-carnitine.Conclusions L-carnitine can inhibit the progress of cardiac hypertrophy.The mechanism may be related to energy metabolism and the protection of myocardial mitochondria.