迷走神经刺激预处理对急性心肌缺血大鼠心肌P物质和降钙素基因相关肽的影响

目的观察迷走神经刺激预处理对急性心肌缺血大鼠心肌组织缺血区和非缺血区P物质(SP)和降钙素基因相关肽(CGRP)表达的影响。方法健康成年雄性SD大鼠24只,体质量270~300g,随机分为3组,每组8只,假手术组(S组)、单纯冠状动脉结扎组(I组)和迷走神经刺激预处理冠状动脉结扎组(VS组)。S组大鼠开胸后在冠状动脉左前降支下穿线不结扎;Ⅰ组大鼠开胸后结扎冠状动脉左前降支;VS组大鼠实施迷走神经刺激30min后结扎冠状动脉左前降支。各组在手术后计时3h。采用免疫组织化学、酶免疫法和反转录-聚合酶链反应法从蛋白和基因水平观察各组大鼠缺血区和非缺血区心肌SP和CGRP的表达。结果Ⅰ组大鼠缺血区心肌SP/SP mRNA和CGRP/β-CGRP mRNA的水平较S组升高(P<0.05),VS组低于Ⅰ组(P<0.05),但仍高于S组(P<0.05)。非缺血区各组的变化趋势类同缺血区,但各扎闭冠状动脉组SP/SP mRNA和CGRP/β-CGRP mRNA的水平均低于相应组缺血区的水平(P<0.05)。结论迷走神经刺激预处理可降低急性心肌缺血大鼠心肌组织SP和CGRP的表达,提示迷走神经刺激预处理可能参与缺血心肌的保护。

Effects of preconditioning with vagal stimulation on substance P and calcitonin gene-related peptide in myocardium following acute myocardial ischemia in rats

Objective To investigate the effects of preconditioning with vagal stimulation on the expression of substance P （SP） and calcitonin gene-related peptide （CGRP） in ischemic and non-ischemic myocardium following a- cute myocardial ischemia in rats. Methods Twenty-four adult male Sprague-Dawley rats weighed 270-300 g were randomly assigned to Sham operation group （group S, n=8）, coronary artery ligation group （group I, n=8） and coronary artery ligation with vagal stimulation for preconditioning group （group VS, n=8）, respectively. The left anterior de- scending branch of coronary artery, whose inferior thread was not ligated in group S, was occluded in group I and fol- lowing a 30-minute vagal stimulation for preconditioning in group VS. This was followed by immunohistochemistry, enzyme immunoassay and reverse transeriptase polymerase chain reaction for determination of the expression of SP mR- NA and β-CGRP mRNA in ischemic and non-ischemic myocardium 3 hours thereafter. Results Significantly in- creased SP/SP mRNA and CGRP/β-CGRP mRNA expression were yielded in isehemic myocardium in group I, fol- lowed by group VS and group S （all P〈0.05）. A similar trend was noted in non-ischemic myocardium in all groups. Additionally, the coronary artery ligation resulted in markedly reduced SP/SP mRNA and CGRP/β-CGRP mRNA ex- pression in ischemic myocardium than in non-ischemic myocardium （all /〉〈0.05）. Conclusion Preconditioning with vagal stimulation attenuates SP and CGRP expression in ischemic myocardium in rats and may have involved in my- ocardial protection.