糖尿病大鼠心肌损伤的观察及机制初探

Research of mechanism of myocardial injury in diabetic rats

目的:探讨不同病程、不同血糖浓度对糖尿病(diabetesmellitus,DM)大鼠的心肌损伤及其机制。方法:SD大鼠64只,随机分为2组:对照组(NC组)32只,实验组(DM组)32只。DM组腹腔注射链脲佐菌素(streptozotocin,STZ)55mg/kg诱发DM模型。实验组和对照组又随机分为4组,每组8只。分别观察病程2周、4周、6周、8周大鼠心功能及心肌组织生化指标的变化。另取SD大鼠40只,随机分出8只作为对照组(NC),其余用上述方法造模,并按最后一次血糖浓度分为3组:16.7～21.6mmol/L(DM1组),21.7～26.6mmol/L(DM2组),26.7mmol/L以上(DM3组)。比较各组大鼠心功能及心肌组织生化指标的变化。结果:与NC组比,DM大鼠第4周心肌LVEDP、-dp/dtmax、MDA含量,第6周除CK外各项指标、第8周心肌各项指标差异均有显著性(P<0.01～0.05)。不同血糖浓度DM大鼠各项指标与NC组差异均有显著性(P<0.01～0.05)。与DM1组比,DM2组LVEDP、-dp/dtmax、t-dp/dt、CK、SOD、MDA差异均有显著性(P<0.01～0.05),DM3组各项指标除LDH外差异均有显著性(P<0.01～0.05);与DM2组比,DM3组LVSP、LVEDP、+dp/dtmax、SOD差异有显著性(P<0.01～0.05)。结论:DM大鼠从第4周开始出现心肌舒张受限,第6周开始出现心肌收缩障碍,心肌组织酶明显改变,随病程延长、血糖浓度升高而逐渐加重。

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