一氧化氮在超声心动图检测冠状动脉反应性充血扩张中的作用

Role of nitric oxide in echocardiographic evaluation of flow-dependent epicardial coronary vasodilation induced by reactive hyperemia in dogs

目的评价一氧化氮(NO)在超声心动图检测冠状动脉反应性充血扩张中的作用。方法健康成年杂种犬12条。应用超声心动图仪分别观察记录基础状态反应性充血试验前后、冠状动脉内注射NO合成抑制剂LNAME时反应性充血试验前后的二维图像。测量冠状动脉左前降支内径(LADd)并计算内径百分变化率。结果基础状态下,反应性充血试验后LADd明显增宽[由(2.23±0.19)mm增为(2.52±0.24)mm,P<0.01],内径百分变化率为(13.10±3.59)%。冠状动脉内注射LNAME时,反应性充血试验前、后LADd与基础状态反应性充血试验前LADd相比差异无显著性意义,内径百分变化率为(1.07±2.97)%,较基础状态显著减小(P<0.001)。结论超声心动图观察到的血流介导性冠状动脉内径的变化与内皮来源的扩血管物质NO有关,超声心动图可用于检测冠状动脉内皮依赖性扩张功能。

Objective To evaluate the role of nitric oxide(NO) in the echocardiographic detection of the flow-dependent epicardial coronary vasodilation induced by reactive hyperemia(RH). Methods In twelve instrumented dogs, the changes of internal diameter of the left anterior descending coronary artery (LADd) were investigated before and after RH under the condition with and without blockade of NO formation by intracoronary infusion of NG-nitro-L-arginine methyl ester(L-NAME), an inhibitor of nitric oxide synthase. LADd was measured using echocardiography. The percent change of LADd was calculated. Results Before intracoronary infusion of L-NAME, LADd increased significantly from (~2.23 ±~0.19 )mm to (~2.52 ±~0.24 )mm (P<~0.01 ) after RH, and the percent change of LADd was (~13.10 ±~3.59) %. After intracoronary infusion of L-NAME, LADd did not change significantly (P>~0.05 ) when compared with that before intracoronary infusion of L-NAME. However, the percent change of LADd after RH with intracoronary infusion of L-NAME was dramatically lower than that without intracoronary infusion of L-NAME [(~1.07 ±~2.97 )% vs (~13.10 ±~3.59 )%, P<~0.001 ]. Conclusions The flow-dependent dilation of LAD detected by echocardiography is associated with endothelium-derived nitric oxide. Echocardiography can be used for assessment of coronary endothelial function.