四氢生物蝶呤对大鼠急性心肌缺血再灌注损伤的保护作用及其机制研究

Protection of tetrahydrobiopterin against acute myocardial ischemia-reperfusion injury in rat and its mechanism

目的研究四氢生物蝶呤对大鼠急性心肌缺血再灌注损伤的保护作用,并探讨其作用机制。方法 Wistar大鼠随机分为对照组、假手术组、模型组及四氢生物蝶呤5、10 mg/kg组,每组10只。结扎左冠状动脉前降支,制备急性心肌缺血再灌注损伤模型。对照组、假手术组和模型组均ig生理盐水2 mL,四氢生物蝶呤组ig四氢生物蝶呤5、10 mg/kg。1次/d,连续给药14 d。导管法测定血流动力学指标:左心室舒张最大速率(-dp/dtmax)、左心室舒张期末压(LVEDP)、左室开始收缩至左室内压上升速率峰值时间(Tau);ELISA法测定血浆脑钠素(BNP)活性;按试剂盒说明测定心肌一氧化氮合酶(eNOS)活性、NO生成量;染色法测定心肌梗死面积,计算心肌梗死程度;免疫组化法测定β3水平。结果与模型组比较,四氢生物蝶呤5、10 mg/kg组-dp/dtmax显著增高,LVEDP显著降低,Tau明显缩短,差异均具有统计学意义(P<0.05、0.01);血浆BNP显著下降,eNOS活性、NO生成量均显著升高(P<0.01);心肌梗死面积更小,心肌梗死程度更轻(P<0.01);β3表达水平升高(P<0.01)。结论四氢生物蝶呤可以减少急性缺血再灌注损伤大鼠心肌梗死面积,改善心肌舒张功能,对大鼠急性缺血再灌注损伤具有保护作用,可能与激活eNOS活性、提高NO生成量和β3受体有关。

Objective To study protective effect of tetrahydrobiopterin against acute myocardial ischemia-reperfusion injury in rat, and discuss its mechanism. Methods Wistar rats were randomly divided into control, Sham, model, and tetrahydrobiopterin（5 and 10 mg/kg） groups, and each group had 10 rats. Rats were ligated the left anterior descending coronary artery and were established acute myocardial ischemia-reperfusion injury models. Rats in the control, Sham, and model groups were ig administrated with normal saline 2 mL, and rats in the tetrahydrobiopterin groups were ig administrated with tetrahydrobiopterin 5 and 10 mg/kg. The treatment were carried out once daily, and lasted for 14 d. Hemodynamic parameters, such as left ventricular diastolic maximum rate（-dp/dtmax）, left ventricular end diastolic pressure（LVEDP）, and left ventricular began to shrink to left ventricular pressure rise rate peak time（Tau） were determined by catheter method. Brain natriuretic peptide（BNP） activity in plasma was determined by ELISA method. Activity of eNOS and NO generation amounts were determined according to kit instructions. The area of myocardial infarction was determined by staining method, the degree of myocardial infarction was calculated, and the level of β3 was determined by immunohistochemistry method. Results Compared with the model group,-dp/dt_（max） in tetrahydrobiopterin（5 and 10 mg/kg） groups were significantly increased, LVEDP were significantly decreased, and Tau were significantly shortened, with significant difference between two groups（P〈 0.05,0.01）. BNP activities in plasma were significantly decreased, activity of eNOS and NO generation amounts were significantly increased（P 〈0.01）. Myocardial infarction areas were smaller, the degrees of myocardial infarction were more light, and β3 expressions were significantly higher in tetrahydrobiopterin（5 and 10 mg/kg） groups（P〈 0.01）. Conclusion Tetrahydrobiopterin can reduce myocardial infarction area in rats with acute myocardial ischemia- reperfusion injury, improve cardiac diastolic function, and has protective effect against acute myocardial ischemia-reperfusion injury in rat, which may be related to activate eNOS activity, improve the NO generation amount and β3 receptors expression.