ADRENERGIC LIMITATION OF CORONARY FLOW DURING EXERCISE

先前的研究表明，一个阿尔法压缩音， 限制了心肌灌注， 心肌收缩功能 由于潜在的重要性， 肾上腺素能对冠状动脉灌注和心肌功能的影响， 在人类的体力消耗，提出了四个新的研究。 研究 其他人的研究表明，α-收缩是由 循环中的儿茶酚胺，而不是神经机制，而飞行员 该实验室的研究表明，神经机制在 作用 因此，研究5将检查冠状动脉α- 缩肌张力主要由体液或神经机制介导。 研究还冲突方面的跨壁分布， α-缩肌张力及其在调节 心肌血流量 研究6将研究他的跨壁性质， 肾上腺素能收缩张力及其对透壁心肌的影响 在运动中发挥作用。 其他人的研究表明， 进行性冠状动脉闭塞，血流减少导致 早在冠状动脉扩张储备之前收缩功能降低 能力已经耗尽。 第七项研究将检验阿尔法巨蟒 语气随着运动的强度而变化， 紧张，作为限制冠状动脉流量的结果， 在最大运动水平下的最大心脏性能。 具体 还将检查所涉及的α-受体亚型。 试点研究 表明在轻度运动期间保持流量恒定会导致 交感神经血管收缩 第8章我想看看 运动时局部缺血引起神经反射， α-缢痕 这些重要的研究将适用于 治疗患有预先存在的冠状动脉疾病的人， 特别是在用力的时候。

Previous studies under this grant indicate that an alpha-constrictor tone limits myocardial perfusion and as a result imposes a limitation on myocardial contractile function. Because of the potential importance of this adrenergic effect on coronary perfusion and myocardial function during physical exertion in the human, four new studies are proposed. Research studies by others suggest that the alpha-constriction is mediated by circulating catecholamines rather than to neural mechanisms, while pilot studies from this laboratory indicate that neural mechanisms play a large role. Therefore, Study 5 will examine whether the coronary alpha- constrictor tone is mediated primarily humoral or by neural mechanisms. Studies also conflict with regard to the transmural distribution of an alpha-constrictor tone and its physiological importance in modulating myocardial blood flow. Study 6 will examine the transmural nature of he adrenergic constrictor tone and its effect on transmural myocardial function during exercise. Studies by others have shown that during progressive coronary occlusion, there is a reduction in flow leading to a reduction in contractile function long before the coronary dilatory reserve capacity is exhausted. Study 7 will examine whether the alpha-constrictor tone varies with the intensity of exercise, and whether the constrictor tone, as a result of restricting coronary flow also imposes a limitation on maximal cardiac performance at maximal levels of exercise. The specific alpha-receptor subtypes involved will also be examined. Pilot studies indicate that holding flow constant during mild exercise induces a sympathetic vasoconstriction. Therefore, Study 8 will examine whether ischemia during exercise elicits a neural reflex which imposes a coronary alpha-constriction. These important studies will be applicable to the treatment of the human with pre-existing coronary artery disease, especially during exertion.