Research of mechanism of myocardial injury in diabetic rats

Objective To observe the effects of course of disease and blood glucose(BG) levels on myocardial injury in diabetic ratsMethods Sixtyfour SD rats were randomly divided into two groups,including normal control group (NC),experimental groups (DM)Diabetes mellitus was induced by the injection of 55 mg/kg streptozotocin (STZ,ip) in ratsThe same volume of citric acid buffer was given in NC group as controlThe heart function and LDH,CK,SOD activities and MDA,NO contents in myocardial homogenate were measured at 2,4,6 and 8 weeks after the setup of DM modelOther forty SD rats were randomly divided into two groups:normal control group (NC,n=20),experimental groups(DM,n=20)The induction of DM was as mentioned aboveAccording to the different levels of BG,diabetic rats were divided into three group,including Group DM1(167～216 mmol/L),Group DM2(217～266 mmol/L) and Group DM3(more than 267 mmol/L)After 4 weeks,the heart function and LDH,CK,SOD activities and MDA,NO contents were measuredResults Compared with NC group,LVEDP and dp/dtmax were significantly decreased(P 005,P 001),MDA content were significantly increased(P 001)All the parameters except CK at 6 weeks and all at 8 weeks had significant difference (P 005,P 001)Compared with NC group,all the parameters between three DM groups had significant difference(P 005,P 001)Compared with Group DM1,LVEDP,-dp/dtmax,t-dp/dt,CK,SOD,MDA in Group DM2 and all but LDH in Group DM3 had significant difference (P 005,P 001)Compared with Group DM2,LVSP,LVEDP,+dp/dtmax,SOD in Group DM3 had significant difference(P 005,P 001)Conclusions Myocardial injury of diabetic rats was aggravated with the prolonged course of the diseases and the increased BG levels