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目的评价内皮衍生超极化因子(EDHF)在血流介导性冠状动脉反应性充血扩张中的作用。方法健康成年杂种犬10条。冠状动脉内注射钾离子通道阻断剂四乙铵(TEA)以抑制EDHF的作用前后,应用超声心动图仪分别观察记录反应性充血试验诱发的冠状动脉左前降支(LAD)内径的变化以及心肌内冠状动脉(I MCA)血流的变化。测量LAD内径、I MCA的峰值血流速度(Vmax)及流速时间积分(VTI),并计算反应性充血试验诱发的百分变化率。结果冠状动脉内注射TEA前后反应性充血试验诱发的LAD内径百分变化率的差异无显著性意义[(12.29±2.61)%vs(10.31±2.89)%,P=0.123]。冠状动脉内注射TEA后反应性充血试验诱发的I MCA的Vmax、VTI的百分变化率却较注射TEA前明显减低[分别为(38.91±17.32)%vs(80.18±11.03)%及(26.50±12.61)%vs(75.86±21.77)%,P均<0.001]。结论应用TEA抑制EDHF的作用对血流介导性正常犬心外膜冠状动脉扩张反应无明显影响,而使I MCA反应性充血程度减小,提示EDHF在大、小冠状动脉的作用不同,EDHF在I MCA内皮血流依赖性扩张反应中起一定作用。
Objective To evaluate the role of endothelial derived hyperpolarization factor (EDHF) in reactive blood flow-mediated coronary hyperemia and dilation. Methods 10 healthy adult mongrel dogs. Coronary injection of potassium channel blocker tetraethylammonium (TEA) to inhibit EDHF before and after the application of echocardiography were recorded reactive hyperemia test recorded changes in left anterior descending coronary artery (LAD) diameter and myocardial Changes of blood flow in the internal coronary artery (I MCA). The inner diameter of LAD, the peak blood flow velocity (Vmax) of I MCA and the time integral of flow velocity (VTI) were measured and the percent change induced by reactive hyperemia test was calculated. Results There was no significant difference in percentage change of internal diameter of LAD induced by reactive hyperemia test before and after intracoronary injection of TEA [(12.29 ± 2.61)% vs (10.31 ± 2.89)%, P = 0.123]. The percent change of Vmax and VTI of I MCA induced by reactive hyperemia test after intracoronary injection of TEA was significantly lower than that before injection of TEA [(38.91 ± 17.32)% vs (80.18 ± 11.03)% vs (26.50 ± 12.61)% vs (75.86 ± 21.77)%, P <0.001]. Conclusion The application of TEA to inhibit EDHF has no significant effect on the echocardiographic dilation of epicardial coronary arteries in normal dogs, and the degree of IMCA reactive hyperemia decreases. It suggests that the effect of EDHF on the small and small coronary arteries is different. EDHF Plays a role in I MCA endothelial blood flow-dependent dilatation.