Effects of recombinant human growth hormone (r-hGH) on the left ventricular remodeling and cardiac function following experimental acute myocardial infarction of rats

Objective To investigate the cardiac effects of Growth Hormone(GH) administration during the early phase of pathologic remodeling in rat model of large myocardial infarction(MI).Methods Remale wistar rats(body weight 220-250 g),were divided randomizedly into three groups:r-hGH group,valsartan group and controlled group.By ligation of coronary artery,acute myocardial infarction(AMI) model of rats was estabolished.The rats of r-hGH group received 4 weeks of treatment with GH,2 mg/kg body weight per day(n=6) from the same day of operation.The rats of valsartan group received 4 weeks of treatment with valsartan,30 mg/kg body weight per day(n=7)from the second day of operation.The rats of control group(n=7) were given 0.9%NS for 4 weeks after operation.Cardiac function parameters such as heart rate(HR),mean artery pressure(MAP),left ventricular systolic pressure(LVSP),left ventricular diastolic pressure(LVDP),left ventricular end-diastolic pressure(LVEDP),left ventricular contractility(±dp/dt) were measured by arterial and intraventricular catheterization.Then the rats were executed,measured the myocardial hypertrophy index(ventricular weight /body weight) and infarct surface area(%of LV).Results At 4th week,the r-hGH group significiently increased in LVSP,±dp/dt as compared with the valsartan and controlled group,while in LVDP,LVEDP decreased.The percent of the surface area of the left ventricle,the r-hGH and lasartan groups were significantly decreased(48.05±12.12,62.31±2.32) as compared with the controlled group(80.05±13.62)(P0.05),and there was no difference between the r-hGH group and lasartan group.The left heart weight/body weight(LHW/BW) of the r-hGH and lasartan groups(2.00±0.22,1.98±0.23) showed much lower than those of the controlled group(2.39±0.11),P0.05),and the decreasing was the lowest in three groups.Conclusion In r-hGH treated myocardial infarction rats,the damaged myocardial function can be recovered significiently after 4 weeks,while the inbititory effect of r-hGH is better than valsartan.Both r-hGH and vasartan have the effects of reversing LVH,vasartan has more stronger function.Experiment myocardial infarct size in rats might be reduced by r-hGH.