一氧化氮在人参皂甙Rb1预处理减轻糖尿病大鼠心肌缺血再灌注损伤中的作用

目的 评价一氧化氮(NO)在人参皂甙Rb1预处理减轻糖尿病大鼠心肌缺血再灌注损伤中的作用.方法 成年雄性SD大鼠,体重220～280g,腹腔注射1%链脲佐菌素-柠檬酸盐缓冲液65 mg/kg制备糖尿病模型.取糖尿病模型制备成功的大鼠40只,随机分为4组(n=10):假手术组(S组)、缺血再灌注组(IR组)、人参皂甙Rb1预处理组(R组)和L-NAME+人参皂甙Rb1预处理组(LR组).IR组、R组和LR组采用结扎左冠状动脉前降支30 min,再灌注120 min的方法制备大鼠心肌缺血再灌注模型;S组只穿线.LR组于缺血前25 min时静脉注射一氧化氮合酶抑制剂N-硝基-L-精氨酸甲酯10 mg/kg;R组和LR组于缺血前10 min时静脉注射人参皂甙Rb1 40mg/kg;S组和IR组给予等容量生理盐水.再灌注120 min时,颈动脉采集血样,测定血清肌酸激酶(CK)和乳酸脱氢酶(LDH)的活性.然后处死大鼠,取心肌组织,计算心肌梗死范围,测定内皮型一氧化氮合酶(eNOS)表达、MDA和NO的含量以及SOD活性,光镜下观察病理结果.结果 与S组比较,IR组、R组和LR组血清CK和LDH的活性升高,心肌梗死范围增大,IR组和LR组心肌eNOS表达下调,MDA含量升高,SOD活性和NO含量降低(P＜0.05);与IR组和LR组比较,R组血清CK和LDH的活性降低,心肌梗死范围减小,心肌eNOS表达上调,MDA含量降低,SOD活性和NO含量升高(P＜0.05);IR组和LR组各指标比较差异无统计学意义(P＞0.05).结论人参皂甙Rb1预处理可通过激活eNOS,促进NO生成,抑制心肌细胞脂质过氧化反应,从而减轻糖尿病大鼠心肌缺血再灌注损伤.

Role of NO in reduction of myocardial ischemia-reperfusion injury by ginsenoside Rb1 preconditioning in diabetic rats

Objective To evaluate the role of by NO in reduction of myocardial ischemia-reperfusion (IR)injury by ginsenoside Rb1 preconditioning in diabetic rats. Methods Forty healthy adult male SD rats weighing 220-280 g were used in this study. Diabetes mellitus was induced by intraperitoneal streptozotocin 65 mg/kg and confirmed by fasting blood glucose ＞ 16.7 mmol/L. The animals were randomly divided into 4 groups ( n = 10each): sham operation group (group S), group IR, ginsenoside Rb1 group (group R) and L-NAME + ginsenoside Rb1 group (group LR). IR was produced by occlusion of the anterior descending branch of left coronary artery (LAD) for 30 min followed by 120 min reperfusion in group IR, R and LR. In group S, LAD was exposed but not occluded. In group LR, L-NAME 10 mg/kg was injected iv 25 min before ischemia. In group R and LR, ginsenoside Rb1 40 mg/kg was injected iv 10 min before ischemia. In group S and IR, eaqual volume of normal saline was injected instead of ginsenoside Rb1. The blood sample was taken from carotid artery at 120 min of reperfusion for determination of serum activities of creatine kinase (CK) and lactate dehydrogenase (LDH). Then the animals were sacrificed and myocadial tissues were obtained for determination of infarct size, endothelial nitric oxide synthase (eNOS) expression, MDA and NO contents, SOD activity and microscopic examination. Results The serum activities of CK and LDH were significantly increased and the myocardial infarct size was enlarged in group IR, R and LR, and eNOS expression was significantly down-regulated, MDA content was increased, and SOD activity and NO content was significantly decreased in group IR and LR compared with group S ( P ＜ 0.05). The serum activities of CK and LDH, and MDA content were significantly decreased, the myocardial infarct size was reduced, the expression of eNOS was up-regulated and the activity of SOD was increased in group R compared with group IR and LR ( P ＜ 0.05). There was no significant difference in the indices mentioned above between group IR and LR ( P＞ 0.05). Conclusion Ginsenoside Rb1 preconditioning can attenuate myocardial IR injury in diabetic rats via activation of eNOS, increase in NO production, and inhibition of the lipid peroxidation reaction.