左旋精氨酸对实验性心肌缺血/再灌注损伤中一氧化氮和内皮素的影响

目的　探讨一氧化氮 (NO)和内皮素 (ET)在心肌缺血 /再灌注损伤 (MIRI)中的作用及左旋精氨酸对其的影响。方法　实验兔分为假手术对照组 (n =10 )、心肌缺血 /再灌注组 (n =10 )及心肌缺血 /再灌注 左旋精氨酸组 (n =10 ) ;分别检测缺血前、缺血 4 0min和再灌注 2 0min 3个时点的指标变化。用硝酸还原酶法检测血浆及心肌组织一氧化氮代谢产物 (NOP)含量 ,放射免疫法测定ET水平 ,酶动力法测定乳酸脱氢酶 (LDH)活性 ,并行心肌电镜观察。结果　心肌缺血 4 0min、再灌注 2 0min血浆NOP明显低于、ET及LDH显著高于假手术对照组 ,尤以再灌注 2 0min变化显著 (均P <0 0 1) ;心肌组织NOP和LDH明显低于、ET显著高于假手术对照组 (P <0 0 5和P <0 0 1) ;心肌超微结构发生异常改变。左旋精氨酸可逆转上述指标的异常变化。结论　缺血 /再灌注导致血管内皮功能紊乱 (即NO水平下降和ET水平升高 ,在MIRI发生发展中起介导作用 ;左旋精氨酸通过保护冠脉内皮 ,提高机体内NO水平和降低机体内ET水平 ,从而减轻MIRI。

Effect of L- arginine on nitric oxide and endothelin in the reperfusion injury after myocardial ischemia in rabbits

Objective To study the role of nitric oxide and endothelin during myocardial ischemia-reperfusion injury(MIRI) and effect of L-arginine(L-Arg) Methods The rabbits were randomly divided into three groups (n=10,in each),sham operated group(A), myocardial ischemia-reperfusion group(B), myocardial ischemia-reperfusion L-arg(C). Nitric oxide products (NOP), endothelin (ET) levels,and lactate dehydrogenase (LDH) activities were measured before ischemia,40 minutes after ischemia and 20 minutes after reperfusion.Meanwhile NOP,ET concentration and LDH activity in myocardium were measured,and the ultrastructure changes of myocardium was observed under electron microscope at 20 minutes after reperfusion.Results Compared with group A,NOP decreased, ET and LDH increased at 40 minutes ( P <0 05 and P <0 01) and more significantly at 20 minutes after reperfusion( P <0 01)in plasma,and NOP and LDH decreased but ET increased ( P <0 05 and P <0 01) at 20 minutes after reperfusion in myocardium and there were abnormal changes of the myocardial ultrastructure at 20 minutes after reperfusion;L-Arg reversed the results of indices mentioned as above markedly.Conclusions The ischemia-reperfusion results in dysfunction of the endothelium (NO level decreasing and ET level increasing)which is an important factor during MIRI,L-Arg reduces MIRI by protecting coronary endothelium(raising NO level and dropping ET level)