一氧化氮对心外膜冠状动脉内皮依赖性扩张的调节作用

Effect of Nitric Oxide on Modulation of Endothelium-dependent Dilation of Epicardial Canine Coronary Arteries

目的 评价一氧化氮在 β 肾上腺素受体介导的心外膜冠状动脉扩张中的作用。 方法 于 6只健康杂种犬冠状动脉内注入一氧化氮合酶特异性阻断剂单甲基精氨酸 (L NMMA ,1mg/kg)前后 ,用经胸超声心动图测量静脉内注入多巴酚丁胺 [5 μg/(kg·min) ]前后左前降支冠状动脉的内径。 结果 多巴酚丁胺注入后 ,左前降支冠状动脉内径从 (2 4 6± 0 2 7)mm扩张到 (2 75± 0 15 )mm ,差异有极显著性意义 (P <0 0 1)。冠状动脉内注入L NMMA (1mg/kg ,5min内注入 )后 ,多巴酚丁胺诱导扩张的左前降支冠状动脉内径从 (2 75± 0 15 )mm缩减到 (2 4 3± 0 37)mm (P <0 0 5 )。结论 血管内皮通过一氧化氮的产生在 β 肾上腺素受体介导的心外膜冠状动脉扩张中起重要作用。

Objective To examine the role of nitric oxide in the β-adrenergic vasodilation of epicardial coronary arteries in dogs. Methods Six dogs were instrumented for measurement of left anterior descending coronary artery diameter by transthoracic echocardiography before and after dobutamine \ with or without intracoronary infusion of NG-monomethyl-L-arginine (L-NMMA) (1 mg/kg). Results The diameter of left anterior descending coronary artery was increased significantly from (2.46±0.27) mm to (2.75±0.15) mm (P<0.01) after administration of dobutamine. Left anterior descending coronary artery diameter in response to dobutamine was decreased significantly from (2.75±0.15) mm to (2.43±0.37) mm (P<0.05) after the intracoronary administration of L-NMMA (1 mg/kg for 5 min) to block nitric oxide synthesis from L-arginine. Conclusion Vascular endothelium contributes to the β-adrenergic dilatory response of epicardial coronary arteries to dobutamine through nitric oxide formation.