糖尿病大鼠在心肌缺血及二氮嗪预处理中一氧化氮信号通路表达受抑的研究

目的:探讨糖尿病对心肌缺血预处理(IPC)及二氮嗪预处理(DPC)效果的影响及其机制。方法:取糖尿病及非糖尿病SD大鼠各40只,建立离体心脏Langendorff灌注模型,各分为5组(每组8只):①对照组(Con组):仅行全心灌流120min,不做其他处理;②缺血再灌注组(I/R组):心脏平衡灌流30min,缺血30min,再灌注60min;③IPC组:缺血30min前,心脏平衡灌流10min,2次缺血5min,再灌注5min后,余同I/R组;④DPC组:心脏依次平衡灌流10 min,重复2次灌注含二氮嗪(浓度为100μmol/L)的K-H液5min,间隔灌注K-H液5min,余同I/R组;⑤二甲基亚砜组(DMSO组):用DMSO取代二氮嗪,过程与DPC组处理相同。比较各组冠状动脉流出液中肌酸激酶(CK)、心肌组织中丙二醛(MDA)、超氧化物歧化酶(SOD)活性及环磷酸鸟苷(cGMP)、NO、一氧化氮合成酶(NOS)含量的变化。电镜对心肌线粒体行Flameng评分。结果:①灌流液CK含量:缺血前各组间差异无统计学意义(P0.05)。再灌注后CK含量比较(与I/R比较):非糖尿病大鼠的IPC组和DPC组明显降低(P0.01);而糖尿病大鼠的IPC组和DPC组无明显降低,(与I/R组比较)差异无统计学意义(P0.05)。②心肌MDA含量:非糖尿病大鼠的IPC组和DPC组含量明显比I/R组降低(P0.01),而糖尿病大鼠的各组差异无统计学意义(P0.05)。心肌SOD含量:非糖尿病大鼠的IPC组和DPC组明显高于I/R组(P0.01),而糖尿病大鼠的各组间差异无统计学意义(P0.05)。③心肌cGMP、NO、NOS含量的变化:非糖尿病大鼠的IPC组及DPC组与I/R组比较明显增加(P0.01);而糖尿病大鼠的组间比较差异无统计学意义(P0.05)。④心肌线粒体Flameng评分:糖尿病大鼠各组间比较,差异无统计学意义(P0.05)。结论:IPC及DPC对非糖尿病大鼠心肌有明显的保护作用,能正调NO、cGMP及NOS的表达。而糖尿病可抑制IPC及DPC的心肌保护作用,其机制可能与糖尿病大鼠心肌NO信号通路表达受抑制有关。

The effect of ischemic and diazoxide preconditioning in diabetes mellitus rat weakens and nitric oxide signal pathway were inhibited

Objective：To explore the effect of ischemic preconditioning （IPC） and diazoxide pretreatment （DPC） on diabetes hearts and its possible mechanism.Methods：Using isolated working rat heart model,40 SD rats with diabetes and 40 non-diabetic SD rats,were divided randomly into 5 groups.The control group （n =8） had a 120min perfusion without any intervension.The I/R group （n =8） had a 30 min equilibration period and a 30min isehemia and a 120min reperfusion.The IPC group（n =8） had a 10min equilibration,then was elicited by two cycles of 5min of ischemia interspersed with 5min reperfusion prior to 30min ischemia and a 120min reperfusion.The DPC group （n =8） had a 10min equilibration and two cycles of 5 min of 100μM diazoxide perfusion followed by a 5min drug-free period before the 30min ischemia and a 120min reperfusion.The dimethyl sulfoxide （DMSO） group （n =8） were perfused with the same treatment as in the DPC group,except that diazoxide was replaced with DMSO.The content of coronary outflow of creatine kinase （CK） in liquid changes,malondialdehyde （MDA） content and superoxide dismutase （SOD） changes of cGMP,NO,nitric oxide syatlase （NOS） content were detected.70nm ultrathin sections were made and the mitochondria under each specimen was evaluated according to Flameng score.Results：CK activity of each group before ischemia content showed no significant difference （P ＞ 0.05）.The content of CK was decreased in the non-diabetic group of IPC group and DPC group （P ＜ 0.01）,while there were no significantly decreased in diabetic group （P ＞ 0.05）.The MDA content in non-diabetic rats in IPC group and DPC group were significantly more than the I/R group （P ＜ 0.01）,but there were no difference in the diabetic group （P ＞ 0.05）.The content of SOD was higher than that in group I/R in non-diabetic rats in IPC group and DPC group （P ＜ 0.01）,while in the diabetic group no statistical differences （P ＞ 0.05）.Changes of myocardial NO,cGMP,and NOS content in non-diabetic group of IPC group and DPC group compared with I/R group increased significantly （P ＜0.01）,while in the diabetic group,showed no significant difference （P ＞ 0.05）.Flameng scores were compared between groups in the diabetic group,the difference was not statistically significant （P ＞ 0.05）.Conclusion：IPC and DPC have obvious protective effects on non-diabetic hearts,and the content of NO,cGMP and NOS were highly expressed.Diabetes could inhibit the effect of IPC and DPC,which may be related with the inhibiting of NO signal pathway in diabetic hearts.