Powell J R, Feigl E O
Circ Res. 1979 Jan;44(1):44-51. doi: 10.1161/01.res.44.1.44.
We studied carotid baroreceptor reflex coronary vasoconstriction in closed-chest dogs with controlled aortic blood pressure and myocardial oxygen metabloism. The dogs were anesthetized with morphine and chloralose. Left coronary blood flow was measured by a cannula-tip flowmeter, and myocardial oxygen metabolism was calculated by measuring the arterial-coronary sinus oxygen difference. A bilateral vagotomy was performed in all animals and they were treated with propranolol. Reduction of carotid sinus pressure to 40 mm Hg caused an increase in aortic pressure that was limited to 15 mm Hg by means of a pressure-control reservoir. During carotid hypotension, heart rate and myocardial oxygen metabolism were unchanged but diastolic conronary vascular resistance increased by 21%. Intracoronary artery infusion of norepinephrine had similar effects. After interruption of the reflex are with the alpha-adrenergic receptor antagonist, dibozane, carotid sinus hypotension and the same increase in aortic pressure (15 mm Hg) resulted in only a 5% increase in diastolic coronary resistance. Dibozane also reduced the coronary responses to norepinephrine. It is concluded that carotid sinus hypotension results in reflex sympathetic alpha-receptor coronary vasoconstriction and that this reflex vasoconstriction is independent of changes in myocardial oxygen metabolism or changes in aortic pressure.
我们在主动脉血压和心肌氧代谢得到控制的开胸犬身上研究了颈动脉压力感受器反射性冠脉血管收缩。犬用吗啡和氯醛糖麻醉。左冠状动脉血流量用插管尖端流量计测量，心肌氧代谢通过测量动脉-冠状窦血氧差来计算。所有动物均行双侧迷走神经切断术，并给予普萘洛尔治疗。通过压力控制贮液器将颈动脉窦压力降至40mmHg，可使主动脉压力升高，但升高幅度限制在15mmHg以内。在颈动脉低血压期间，心率和心肌氧代谢未变，但舒张期冠脉血管阻力增加了21%。冠状动脉内注入去甲肾上腺素也有类似作用。用α-肾上腺素能受体拮抗剂二氮嗪阻断反射弧后，颈动脉窦低血压及相同幅度（1５mmHg）的主动脉压力升高仅使舒张期冠脉阻力增加5%。二氮嗪还可减弱冠脉对去甲肾上腺素的反应。结论是，颈动脉窦低血压可导致反射性交感α受体介导的冠脉血管收缩，且这种反射性血管收缩与心肌氧代谢变化或主动脉压力变化无关。
