外源性降钙素基因相关肽改善体外循环再灌注后冠状微循环的研究

Exogenous CGRP to improve coronary microcirculation after myocardial reperfusion during cardiopulmonary bypass

目的 研究体外循环全心缺血 -再灌注损伤时冠状微循环的动态变化以及外源性降钙素基因相关肽 (CGRP)的心肌保护作用。方法 建立猪体外循环心肌缺血 -再灌注模型 ,分别于心肌再灌注前后不同时间点观测心肌微区灌流量、微血管形态和微血流动态的变化 ;并以外源性CGRP作为心肌麻痹液的组成部分 ,观测其对冠状微循环的影响。结果 心肌再灌注后表现为明显的冠状微循环障碍 ,应用CGRP组在再灌注后各时间点的心肌微区灌流量、微血管形态和微血流动态均较对照组明显改善 ,心功能亦显著改善。结论 体外循环心肌再灌注后出现了冠状微循环障碍 ,外源性CGRP作为心肌麻痹液的组成部分可改善体外循环心肌再灌注后心脏的微循环功能 ,从而起到心肌保护作用。

Objective To observe the changes of myocardial microcirculation after ischemia-reperfusion during cardiopulmonary bypass (CPB) and the effects of exogenous calcitonin gene related peptide (CGRP) on myocardial protection. Methods In vivo porcine models, 10 controls and 10 CGRP used animals (CGRP group) were performed on median sternotomy followed by a standard CPB. All the hearts were arrested for 45 minutes. In the CGRP group, 1?μg/kg CGRP was added into the cardioplegia, and reperfused into the aortic root before the removal of aortic clamp seperately. In both groups, myocardial microvascular perfusion, coronary arterial microvessel diameter and microvessel blood flow on the right atrium were detected by a laser doppler flowmeter and a contact microscope with TV monitor on five consecutive point of time ( before aortic clamping, 5, 30, 60 and 120 minutes after reperfusion). Results The myocardial microvascular perfusion was markedly decreased and coronary arterial microvessels became much thinner and pulsatile flow appeared when the heart was reperfused. It indicated the dysfunction of the coronary microcirculation. Myocardial microvascular perfusion was significantly higher and coronary arterial microvessel diameter was larger in the CGRP group on each point of time of reperfusion compared to those in the control group. In the CGRP group, microvessel blood flow also improved significantly than that in the control group during reperfusion. Conclusions Myocardial microcirculation disorders exist in cardiac ischemia reperfusion during CPB. As a component of cardioplegia, CGRP improves the myocardial microcirculation and could become a new, potent myocardial protector.