L-精氨酸对兔右冠状动脉缺血再灌注时窦房结功能及房室结传导有效不应期的干预作用

Effect of L-arginine on rabbit sinoatrial node functions and atrioventricular nodal effective refractory period during ischemia-reperfusion of the right coronary artery

目的观察L-精氨酸(L-Arg)对兔右冠状动脉缺血再灌注(IR)窦房结(SAN)传导时间(SACT)和恢复时间(SNRT)及房室结(AVN)传导有效不应期(AVERP)的影响。方法在体成年兔右冠状动脉缺血再灌注模型分4组正常对照组,IR(缺血90min,再灌注90min)+生理盐水组,IR+L-Arg组和IR+左型精氨酸甲酯(L-NAME)组。在不同时相分别测定各组心房快速起搏或程序电刺激后的SACT、SNRT和AVERP。结果IR+L-Arg组缺血期及再灌注早期3项指标均有不同程度的下降,而再灌注后期升高;IR+L-NAME组结果却基本相反(P<0.01)。3组组内比,IR+L-Arg组和L-NAME组于缺血期与再灌早期3项指标均升高;再灌注后期,IR+L-Arg组无治疗意义甚至加重SAN和AVN损伤,而IR+L-NAME组3项指标下降。结论随着缺血时间延长SAN功能损伤加重;早期再灌注损伤敏感;组织内适当补充L-Arg,于缺血期和再灌早期对SAN电生理功能和AVERP恢复是有益的,于再灌注后期可能加重损伤。

Objective To study the effect of L-arginine (L-Arg) on sinoatrial conduction time (SACT) and sinus node recovery time (SNRT) and atrioventricular nodal effective refractory period (AVERP) in the course of ischemia- reperfusion (IR) of the right coronary artery in rabbits. Methods Thirty-two rabbit models of ischemia-reperfusion of the right coronary artery were randomly divided into control group, IR+saline group, IR+L-Arg group and IR+ L-arginine-methyl ester (IR+L-NAME group, 8 rabits in each group. At different time points after ligation or loosening of the artery , SACT, SNRT and AVERP were measured respectively by fast pacing of the right atrium and programmed electrical stimulations. Results Compared with the control group, SACT, SNRT and AVERP of the other groups were all prolonged significantly(P<0.01). In comparison with IR+NS group, at each time point , SACT, SNRT and AVERP of IR+L-Arg group were decreased during ischemia and in the early phases of reperfusion, followed by elevation during the latter stages of the reperfusion, as were contrary to the changes in IR+L-NAME group. Conclusions The longer duration of ischemia persists, the severer are the functional damages of the sinoatrial node. Adequate supply of L-Arg to the tissues during ischemia and the early stages of the reperfusion may alleviate the damages, but its administration in the latter stages of reperfusion might contribute to the contrary result.