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 左心室搏动时冠脉微循环的变化 那只猫。心脏跳动中微循环的研究 运动的主要来源，呼吸和心脏，必须是 以某种方式消除或补偿的。要最小化 呼吸诱导的运动动物通过高位呼吸。 频率喷射通风。其次，小动脉的运动会 通过频闪镜观察血管来补偿 通过计算机实现与心脏周期同步的照明 这使得微血管系统看起来是静止的。 微血管直径可以测量，压力可以测量 通过计算机控制的吸管微操作器获得 和Seronull技术。初步使用这些技术 对5-羟色胺的研究表明， 大于100毫米的小动脉收缩，而小动脉 在同样的刺激下，小于100毫米的细胞会扩张。 加压素产生相反的作用：小动脉扩张 直径大于100毫米，小动脉收缩较少 而不是100毫米。这项提议将检验这样一个假设： 冠脉微循环的不同节段会对 不同于普通的刺激措施。具体问题是 这些研究包括：1)5-羟色胺是如何 改变微血管动力学(压力和直径)在不同的 冠脉循环的节段？其机制是什么？ 与这些差异反应有关吗？2)这些差异反应的分布 微血管阻力发生了质的变化 迷走神经刺激后的方式与外源性给药 乙酰胆碱？3)迷走神经 刺激与交感神经系统在刺激反应中的作用 微循环？4)内皮在微循环中的作用是什么 节段性微血管对体液制剂的反应？和，5) 像急性高血压这样的病理生理刺激是如何 改变微血管对体液因子的反应。这些 对微循环的研究可能在概念上提供 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.