Alpha-adrenergic regulation of the coronary circulation in the conscious dog.
Alpha-adrenergic regulation of the coronary circulation in the conscious dog.
复制标题
清醒狗冠状动脉循环的α-肾上腺素调节。
DOI：
10.1016/0002-9149(83)90172-8
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发表时间：
1983
期刊：
影响因子：
--
通讯作者：
Vatner,SF
中科院分区：
文献类型：
--
作者：
Vatner,SF
为了研究神经和体液因素在没有全身麻醉和近期手术并发症的清醒动物冠状动脉血管活动控制中的作用，我们在狗的主动脉和左心室安装了微型压力表来测量主动脉和左心室压力，在左旋冠状动脉安装了血流探头来测量冠状动脉血流。手术恢复几周后，在清醒的狗身上进行实验。刺激颈动脉化学感受器反射引起双相反应；最初观察到惊人的反射性冠状动脉血管舒张：冠状动脉血流量增加了两倍，即使代谢因素的变化通过心得安预处理最小化。化学受体反射性冠状动脉舒张是由胆碱能激活和α -肾上腺素能张力的戒断介导的。第二阶段的反应包括冠状动脉血管阻力的增加，与动脉压升高和冠状动脉血流量和冠状窦氧含量的绝对减少有关。α -肾上腺素能阻断可消除后期冠状动脉收缩。静脉输注肾上腺素能激动剂甲氧沙明使平均动脉压升高65±5%，冠状动脉总阻力升高92±14%。为了确定大冠状动脉是否也受到自主控制，在狗的左旋冠状动脉的相对表面上放置一对超声晶体，直接连续测量其直径。甲氧基胺显著减小冠状动脉横截面积，从而收缩大冠状动脉和阻力冠状血管。因此，虽然冠状动脉受心肌代谢需求变化的调节，但它们也对神经刺激的变化作出反应。最显著的变化是在α -肾上腺素能收缩张力的增强和消退时观察到的，这似乎对大血管和小血管的控制都很重要。
To examine the role of neural and humoral factors in the control of coronary vasoactivity in conscious animals in which the complicating effects of general anesthesia and recent surgery were absent, dogs were instrumented with miniature pressure gauges in the aorta and left ventricle to measure aortic and left ventricular pressures and with flow probes in the left circumflex coronary artery to measure coronary blood flow. Several weeks after recovery from operation, experiments were conducted in the conscious dogs. Stimulation of the carotid chemoreceptor reflex elicted a biphasic response; initially striking reflex coronary vasodilation was observed: Coronary blood flow tripled even after changes in metabolic factors were minimized by pretreatment with propranolol. The chemoreceptor reflex coronary vasodilation was mediated both by cholinergic activation and withdrawal of alpha-adrenergic tone. The second phase of the response involved an increase in coronary vascular resistance, associated with elevated arterial pressure and an absolute reduction in coronary blood flow and coronary sinus oxygen content. The later period of coronary vasoconstriction was abolished by alpha-adrenergic blockade. Intravenous infusion of the alpha-adrenergic agonist methoxamine increased mean arterial pressure by 65 ± 5% and total coronary vascular resistance by 92 ± 14%. To determine whether the large coronary arteries were also under autonomic control, the dogs were instrumented with a pair of ultrasonic crystals on opposing surfaces of the left circumflex coronary artery to measure its diameter directly and continuously. Methoxamine reduced coronary cross-sectional area substantially, thereby constricting large coronary arteries and resistance coronary vessels. Thus, while the coronary arteries are regulated by changes in myocardial metabolic demands, they are also responsive to changes in neural stimuli. The most striking changes were observed with augmentation and withdrawal of alpha-adrenergic constrictor tone, which appear to be important in the control of large as well as small coronary vessels.