Gypenosides On Cardiac Function In Rats With Diabetic Cardiomyopathy

The therapeutic effect of gypenosides on the dysfunction of cardiac muscle in diabetes was investigated in this paper.Fifty Sprague-Dawley rats were randomly divided into the following groups:control, diabetic cardiomyopathy and diabetic cardiomyopathy treated with gypenosides.The diabetic cardiomyopathy in rats was induced by injecting streptozotocin(STZ,55 mg/kg,ip). Seven weeks after rats suffered from diabetes,they received gypenosides with different dosages(50,100 or 200 mg/kg per day)orally for six weeks.In the meanwhile,the pure water was given to one group of diabetic and normal rats as controls.Subsequently,the functions of cardiac muscle,such as left ventricular systolic pressure(LVSP),left ventricular end diastolic pressure(LVEDP),±dp/dt_max,and t-dp/dt,as well as the activities of nitric oxide synthase(NOS),cardiac Ca²⁺-ATPase and Na⁺-K⁺-ATPase were measured.The ultrastructure of cardiac muscle was examined by using electron microscopy.The mRNA expression levels of the cytoskeletal protein(titin and nebulin)in control,diabetic cardiomyopathy and middle dose gypenosides group were detected by reverse transcriptase polymerize chain reaction(RT-PCR).The results indicated that(1)the images of cardiac muscles under electron microscopy in diabetic rats showed the degeneration of myofibrillae and the edema of mitochondria and LVSP,LVEDP,±dp/dt_maxand t-dp/dt,as well as the activities of NOS, cardiac Ca²⁺-ATPase and Na⁺-K⁺-ATPase in rats with diabetic cardiomyopathy were significantly lower than those in controls;(2)The activities of NOS,cardiac ATPases and the function of cardiac muscles in diabetic rats with middle and high dose gypenosides treatment were higher than those without giving gypenosides and the degeneration of myofibrillae was not observed in diabetic cardiomyopathy rats with gypenosides treatment;(3)Titin and nebulin mRNA expression in myocardial was lower in DC group than those in control group and gypenosides didn't increase mRNA expression level of titin and nebulin.With these results,we can come to the conclusion that(1)the myocardial ultrastructure was destroyed and cardiac function was depressed in diabetic cardiomyopathy rats and the mRNA expression of titin and nebulin in diabetic cardiomyopathy rats was decreased;(2)the gypenosides secure cardiac muscles and their function from diabetic impairment and its effect is related to an increase of activities of cardiac NOS,Ca²⁺-ATPase and Na⁺-K⁺-ATPase.