强化胰岛素治疗拮抗严重烫伤大鼠心肌细胞凋亡的作用

目的 了解强化胰岛素治疗对重度烫伤大鼠心肌细胞的抗凋亡作用及机制.方法 将18只SD大鼠分为3组,每组6只.烫伤组及强化组大鼠背部脱毛后造成30%TBSA的Ⅲ度烫伤.强化组伤后静脉注射胰岛素等渗盐水(15 mU·kg-5·min-1)和100 g/L葡萄糖;烫伤组给予等渗盐水(2 mL·kg-1·1%TBSA-1·8 h-1);假伤组模拟烫伤,伤后给予生理量的液体.记录3组大鼠伤后6 h的左心室压力最大上升/下降速率(±dp/dt max);采用原位末端标记法和DNA梯带法检测各组大鼠心肌细胞凋亡情况;蛋白质印迹法检测心肌组织中磷酸化蛋白激酶B(p-Akt)、Bcl-2的表达水平.结果 假伤组、强化组、烫伤组大鼠+dp/dt max值分别为(5.5±0.5)x 103、(3.4±0.4)×105、(2.5±0.5)×103mm Hg/s(1 mm Hg=0.133 kPa);-dp/dt max值分别为(4.55±0.34)× 103、(2.94±0.22)× 103、(2.05±0.19)× 103mm Hg/s.烫伤组大鼠±dp/dt max均低于强化组(P＜0.01).烫伤组大鼠心肌细胞凋亡指数[AI,(13.1±3.4)%]明显高于假伤组[(0.6±0.4)%,P＜0.01];强化组AI为(6.7±1.8)%,明显低于烫伤组(P＜0.01).假伤组大鼠心肌组织未见DNA断裂条带,烫伤组可见明显的DNA断裂形成梯带,而强化组梯带形成不明显,表示其凋亡细胞明显少于烫伤组.烫伤组心肌组织内p-Akt和Bcl-2蛋白表达水平明显低于强化组.结论 强化胰岛素治疗通过上调Akt活性,增加Bcl-2的表达,可能是其抗心肌细胞凋亡、保护心功能的机制之一.

The anti-apoptosis effect of intensive insulin treatment on cardiac myocytes in severe scald rats

Objective To investigate the anti-apoptosis effecl of intensive insulin treatment on cardiac myocytes and its underlying mechanism in severe scald rats. Methods Twelve SD rats were suffered from 30%TBSA full thickness scald,and they were divided into:IT group[with intravenous injection of isotonic with treatment of fluid at physiologic dose].+dp/dtmax(the rate of the rise of left ventricular pressure)and-dp/dtmax(the rate of the fall ofleft ventricular pressure)at 6 post bum hour(PBH)were recorded.Apoptosis were determined by TUNEL staining and DNA ladder.The phosphorylation f Akt and protein ex-pression of Bcl-2 in cardiomyocyte were assayed by Western blotting. Results The+dp/dtmax in the S group,IT group and B group at 6 PBH were respectively(5.5±0.5)× 103 mm Hg/s,(3.4±0.4)×103mm Hg/s and(2.5±0.5)×103 mm Hg/s(1 mm Hg=0.133 kPa),the-dp/dtmax were respectively (4.55±0.34)× 103mm HS/s,(2.94±0.22)× 103 mm HS/s and(2.05±0.19)× 103mm Hg/s.The ±dp/dtmax in IT group was significantly higher than those in B group(P＜0.01).The apoptosis index in B group was(13.1±3.4)%,which was obviously higher than that in IT group(6.7±1.8)%and S group (0.6±0.4)%(P＜0.01).DNA ladder showed that no DNA fragmentation in S group,but obvious DNA fragmentation forming ladder pattern in B group,and no obvious ladder pattern in IT group.The phosphoryla-tion of Akt and level of Bcl-2 protein in B group were markedly higher than those in IT group(P＜0.05 or P<0.01). Conclusion Intensive insulin treament can upregulate the activity of Akt and enhance the expression of Bcl-2,and they might constitute the mechanisms for anti-apoptosis in cardiomyoctye and protec-tion of cardiac function.