CORONARY MICROVASCULAR RESPONSES TO HUMORAL SUBSTANCES

我们实验室最近的技术进步使研究成为可能 冠状动脉微循环在跳动的左心室， 为了研究心脏跳动中的微循环， 运动的主要来源，呼吸和心脏，必须 以某种方式消除或补偿。 以最小化 动物通过高压通风 高频喷射通气 其次，小动脉运动将 通过频闪镜观察血管进行补偿 通过计算机与心动周期同步的照明 这使得微脉管系统看起来是静止的。 可以测量微血管直径或可以测量压力。 用计算机控制的移液管显微操作器获得 和伺服技术。 利用这些技术，初步 对5-羟色胺的研究表明， 直径大于100毫微的小动脉收缩， 小于100微米的细胞对相同刺激的反应是扩张。 血管加压素产生相反的作用：扩张小动脉 大于100微米，小动脉收缩较小 大于100毫微米。 这一提议将检验以下假设： 冠状动脉微循环的不同部分将响应 与普通刺激不同。 具体问题是 在这些研究中检查的是：1）5-羟色胺如何 改变微血管动力学（压力和直径）， 冠状动脉循环的一部分 有哪些机制 参与了这些不同的反应？ 2)的现代化布局 微血管阻力改变， 迷走神经刺激与外源性给药后的方式 乙酰胆碱？ 3)迷走神经和神经元之间的相互作用是什么？ 刺激和交感神经系统的反应， 微循环 4)内皮细胞在 节段性微血管对体液因子的反应（5） 病理生理刺激如急性高血压 改变微血管对体液因子的反应。 这些 对微循环的研究可以从概念上提供 冠状动脉血管调节的重要信息 微循环水平的阻力。

Recent technical advances in our laboratory make possible studies of the coronary microcirculation in the beating left ventricle of the cat. To study the microcirculation in the beating heart two major sources of movement, respiratory and cardiac, must be eliminated or compensated for in some way. To minimize respiratory-induced motion the animals are ventilated by high frequency jet ventilation. Secondly, arteriolar movement will be compensated for by visualizing the vessels with stroboscopic illumination synchronized to the cardiac cycle by a computer which makes the microvasculature appear to be stationary. Microvascular diameters can be measured or pressures can be obtained with a computer controlled pipette micromanipulator and the servonull technique. Using these techniques preliminary studies with 5-hydroxytryptamine have demonstrated that arterioles greater than 100 millimicron constrict while arterioles less than 100 millimicron dilate in response to the same stimulus. Vasopressin produces opposite effects: dilation of arterioles greater than 100 millimicron and constriction of arterioles less than 100 millimicron. This proposal will test the hypothesis that different segments of the coronary microcirculation will respond differently to a common stimulus. The specific questions to be examined in these studies are: 1) How does 5-hydroxytryptamine alter microvascular dynamics (pressure and diameter) in different segments of the coronary circulation? What are the mechanisms involved in these differential responses? 2) Is the distribution of microvascular resistance altered in a qualitatively different manner following vagal stimulation vs exogenously administered acetylcholine? 3) What is the interaction between vagal stimulation and the sympathetic nervous system in the response of the microcirculation? 4) What is the role of the endothelium in the segmental microvascular responses to humoral agents? and, 5) How does a pathophysiologic stimulus such as acute hypertension alter the microvascular response to humoral agents. These studies on the microcirculation may provide conceptually important information on the regulation of coronary vascular resistance at the microcirculatory level.