Effects Of Recombinant Human Growth Hormone (r-hGH) On The Left Ventricular Remodeling And Cardiac Function Following Experimental Acute Myocardial Infarction Of Rats

Objective we sought to investigate the cardiac effect of Growth Hormone (GH) administration during the early phase of pathologic remodeling in rat model of large mvocardial infarction (Ml). Evidence suggests that exogenous administration of GH evoke a hypetrophic response and increases left ventricular (LV) function in vivo in rats with normal or chronically failing hearts . Recent study also suggests that GH has an important effect in treatment of cardiac functional insufficiency in human .We hypothesized that these effects would attenuate ventricular remodeling early after MI .So the present study was designed to determine whether GH would be beneficial when mvocardial infarct in rats has occurred. Methods Remale wislar rats (body weight 220~250g) ,We divided randomizedly into three groups : r-hGH group , valsartan group and controlled group . By ligation of coronary artery , acute mvocardial infarction (AMI) model of rats was estabolished . The rats of r-hGH group receive 4 weeks of treatment with GH , 2mg/kg body weight per day (n=6) from the same day of operation . The rats of valsartan group receive 4 weeks of treatment with valsartan .30ing/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 4weeks 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-diaslolic pressure (LVEDP) .left ventricular contractility (?dp/dt;) were measured by arterial and intraventricular cathcteri/.alion Then the rats were executed , measured the myocardial hypertrophy index (ventricular weight /body weight) and infarcl surface area (%of LV).Results At 4th week .the r-hGH group significienlly increased in LVSP, ±dp/dt; as compared with the valsartan and controlled group, while inLVDP,LVEDP decreased. The percent of the surface area of the left ventricle ,the r-hGH and lasartan groups were significient decreased (48. 05±12. 12 ,62.31±2.32) as compared with the controlled group(80. 05 ± 13. 62) ( P<0.05 ) ,and tliere were 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). (P<0.05) and the decreasing is the lowest in three groups. Conclusion In r-hGH treated myocardial infarction rats, the damaged myocardial function can be recovered significienlly after 4 weeks, while the inbititory effect of r-hGH is better to 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.