ADRENERGIC LIMITATION OF CORONARY FLOW DURING EXERCISE

以前在这项资助下的研究表明，阿尔法收缩音调 限制心肌灌注量，因此对 心肌收缩功能。因为潜在的重要性 这种肾上腺素能对冠脉血流灌注和心肌功能的影响 关于人体的体力消耗，提出了四项新研究。研究 其他人的研究表明，阿尔法收缩是由 飞行员循环中的儿茶酚胺，而不是神经机制 这个实验室的研究表明，神经机制在很大程度上 角色。因此，研究5将检查冠状动脉α- 收缩音主要是由体液或神经机制调节的。 关于跨壁分布的研究也相互矛盾。 α-收缩音调及其在调节中的生理意义 心肌血流量。研究6将检查He的跨壁性质。 肾上腺素能收缩张力及其对跨壁心肌的影响 在运动过程中发挥作用。其他人的研究表明，在 进行性冠状动脉闭塞，血流减少导致 早在冠状动脉扩张性储备之前收缩功能就降低了 运力已耗尽。研究7将检查阿尔法收缩肌 音调会随着运动强度的不同而不同，以及是否会收缩 作为限制冠脉血流的结果，音调也对 在最大运动水平时的最大心脏功能。具体的 还将检查所涉及的阿尔法受体亚型。试点研究 表明在温和的运动中保持恒定的流量会导致 交感神经血管收缩。因此，研究8将检查是否 运动中的缺血引起神经反射，从而导致冠状动脉 阿尔法收缩。这些重要的研究将适用于 治疗已经存在的冠状动脉疾病的人类， 尤其是在劳累的时候。

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.