Buffington C W, Feigl E O
Circ Res. 1983 Nov;53(5):613-21. doi: 10.1161/01.res.53.5.613.
The transmural distribution of alpha-receptor coronary vasoconstriction was studied in 14 closed-chest, morphine- and chloralose-anesthesized dogs. The alpha-receptor-blocking agent, phenoxybenzamine (0.25 mg/kg), was infused into either the anterior or circumflex coronary artery while collection of coronary sinus blood minimized recirculation. The left main coronary artery was cannulated and perfused at constant pressure. Myocardial lactate extraction and blood flow (9 micron radioactive microspheres) were measured during adrenergic activation with intracoronary norepinephrine (2 micrograms/min) at coronary artery pressures of 100, 70, 50, and 38 mm Hg. Flow was 15-25% less in the control region (alpha-receptors intact) than in the alpha-receptor-blocked region, in all layers of the left ventricular wall, at coronary pressures of 100 and 70 mm Hg. When coronary pressure was 50 mm Hg, lactate production resulted (-4% extraction) and significant alpha-receptor vasoconstriction was observed in the outer layer, but was marginal (P = 0.043) in the inner layer, of the left ventricle. Flows were not different in control and alpha-receptor-blocked regions at a coronary pressure of 38 mm Hg (lactate extraction -49%). These data indicate a uniform transmural alpha-receptor vasoconstriction at normal coronary artery pressures that diminished as the heart was progressively underperfused.
在14只闭胸、用吗啡和水合氯醛麻醉的犬中，研究了α受体介导的冠状动脉血管收缩的透壁分布情况。在向冠状动脉窦采血以尽量减少再循环的同时，将α受体阻断剂酚苄明（0.25mg/kg）注入前降支或左旋支冠状动脉。将左冠状动脉主干插管并在恒定压力下灌注。在用冠状动脉内注射去甲肾上腺素（2微克/分钟）进行肾上腺素能激活期间，在冠状动脉压力为100、70、50和38mmHg时，测量心肌乳酸摄取和血流量（9微米放射性微球）。在冠状动脉压力为100和70mmHg时，左心室壁各层中，对照区域（α受体完整）的血流量比α受体阻断区域少15%-25%。当冠状动脉压力为50mmHg时，出现乳酸生成（摄取率为-4%），并且在左心室外层观察到明显的α受体血管收缩，但在内层则不明显（P=0.043）。在冠状动脉压力为38mmHg时（乳酸摄取率为-49%），对照区域和α受体阻断区域的血流量没有差异。这些数据表明，在正常冠状动脉压力下，α受体介导的血管收缩呈均匀的透壁分布，随着心脏灌注逐渐不足，这种收缩作用减弱。
