CORONARY MICROVASCULAR RESPONSES TO HUMORAL SUBSTANCES

这项建议的目的是评估两者的血管舒缩反应 体内天然和成熟的侧支动脉和小动脉 通过直接将络脉可视化来刺激神经体液和生理刺激 犬左室微血管。侧支微血管 在心外膜上将使用两种技术进行可视化。第一, 使用高频喷射将呼吸诱导的运动降至最低 通风与心脏周期同步。第二，心脏的运动 由于使用计算机控制的收缩会得到补偿 频闪外照射与心跳周期同步。 频闪照明在视觉上冻结了心脏的运动 通过显微视频实现微循环的可视化 数字化系统。因此，在不受限制的心脏血管舒缩反应中 可以测量30到400微摩尔的微血管。微血管 压力将使用计算机控制的机电设备获得 微型吸管夹持器和伺服零位技术。抵押品将是 左前降支和左回旋支之间的视觉轨迹 使用荧光血管造影术的动脉。对本机和 刺激的侧支将被测量以检验以下假设 自然络脉和刺激络脉对神经体液刺激的反应 生理刺激将取决于初始血管大小 与非抵押性血管相似。只有使用这些技术才能 可视化血管运动反应的冠脉微循环 可以在活体内直接测量络脉。具体目标是 本提案涉及：1)确定双方的反应 血管扩张剂的天然和刺激侧支(硝酸甘油， 乙酰胆碱)和血管紧张剂(5-羟色胺、内皮素、加压素 和PGF2Alpha)；2)确定天然络脉对 降低灌流压力和血管扩张剂储备 络脉中的硝酸甘油或腺苷 限流性狭窄或完全闭塞；3)确定 天然络脉对5-羟色胺的反应在存在时增强 限流性狭窄或完全冠状动脉闭塞；以及4) 测定正常人和正常人的微血管压分布 人体成熟络脉及其微血管阻力分布的研究 心肌依赖于刺激的络脉。

The objective of this proposal is to assess vasomotor responses of both native and mature collateral arteries and arterioles in vivo to neurohumoral and physiological stimuli by directly visualizing collateral microvessels on the left ventricle of the dog. Collateral microvessels on the epicardium will be visualized using two techniques. First, respiratory-induced motion is minimized using high frequency jet ventilation synchronized to the heart cycle. Second, motion of the heart due to contraction will be compensated for using computer-controlled stroboscopic epi-illumination synchronized to the cardiac cycle. Stroboscopic illumination visually freezes the motion of the heart enabling visualization of the microcirculation with a microscopic-video digitizing system. Thus, in an unrestrained heart vasomotor responses of microvessels from 30 to 400 micromoles can be measured. Microvascular pressures will be obtained using a computer-controlled electromechanical micropipette holder and the servo-null technique. Collaterals will be visually traced between the left anterior descending and left circumflex arteries using fluorescence angiography. Responses to both native and stimulated collaterals will be measured to test the hypothesis that the response of both native and stimulated collaterals to neurohumoral and physiological stimuli will be dependent upon the initial vessel size similar to non-collateral vessels. It is only with these techniques to visualize the coronary microcirculation that vasomotor responses of collaterals can be directly measured in vivo. The specific aims to be addressed in this proposal are: 1) to determine the response of both native and stimulated collaterals to vasodilators (nitroglycerin, acetylcholine) and vasoconstrictors (serotonin, endothelin, vasopressin and PGF2alpha.); 2) to determine the response of native collaterals to decreases in perfusion pressure and the vasodilator reserve with nitroglycerin or adenosine of collaterals in the presence of a flow-limiting stenosis or total occlusion; 3) to determine whether the response of native collaterals to serotonin is augmented in the presence of a flow-limiting stenosis or total coronary occlusion; and 4) to determine the distribution of microvascular pressures in native and mature collaterals and the distribution of microvascular resistance in myocardium dependent upon stimulated collaterals.