一氧化氮在重复可逆性心肌缺血再灌注所致的心肌顿抑时的动态变化及其意义

The trends and significance of changes of nitric oxide in myocardial stunning caused by the recurrent reversible myocardial ischemia-reperfusion

目的 了解在重复可逆性心肌缺血再灌注所致的心肌顿抑时 ,血液中一氧化氮 (NO)的动态变化及其与心功能的关系 ,并采取促进或抑制NO的方法 ,观察心功能的变化规律。方法 新西兰兔 15只 ,随机分为 3组 (每组 5只 ) :分别为对照组、在静脉内注射NO合成底物L 精氨酸为L Arg组、在静脉内注射一氧化氮合酶抑制剂L 硝基 精氨酸为L NNA组。兔用戊巴比妥钠静脉注射麻醉后 ,结扎前降支制成心肌缺血再灌注模型 ,用电子自旋共振法测定血液中NO含量 ,同时记录左心室最大上升速率dP dtmax、左心室舒张末压力、心率、血压。使兔心肌缺血 10min ,共 3次 ,第 1、2次缺血后再灌注 10min ,第 3次缺血后再灌注 12 0min。结果 3组的dP dtmax在第 1次缺血 5min时已经下降。但是在第 1次再灌注 5min时L Arg组NO明显升高 ,与对照组比较 ,P <0 .0 5 ;L NNA组NO明显下降 ,与对照组比较 ,P <0 .0 1;L Arg组dP dtmax明显下降 ,与对照组比较 ,P <0 .0 5 ;L NNA组dP dtmax明显改善 ,与对照组比较 ,P <0 .0 5。结论 再灌注早期NO的大量生成是加重心肌顿抑的原因之一。

Objective To observe the relationship between the level of NO detected by ESR in the blood and the myocardial stunning caused by the recurrent, reversible myocardial ischemia-reperfusion injury(MIRI).Methods Fifteen New Zealand white rabbits were randomly divided into three groups: (1) control group,n=5;(2) L-Arg group,n=5;(3) L-NNA(L-nitro-arginine) group,n=5. The rabbits were anesthetized with intravenous pentobarbital. A suture ligature was passed around the left anterior descending coronary artery(LAD), so the artery could be occluded and reperfused. The LAD was occluded for 10 min three times and the first and second occlusions were followed by 10 min of reflow. After the third occlusion, the reperfusion was 120 min.Results In all groups,dP/dt max began to decrease at 5 min after the first ischemia.Compared with control group at 5 min after first reperfusion,NO level in L-Arg group was elevated significantly,P< 0.05;while in L-NNA group,NO decreased significantly,P<0.01.In comparison with the control group, dP/dt max in L-Arg group decreased significantly,P<0.05;while in L-NNA group,dP/dt max improved significantly,P<0.05.Conclusions The fact that NO level was elevated suggest that NO has a harmful effect on myocardial stunning at the early stage.