Marcus M L, Chilian W M, Kanatsuka H, Dellsperger K C, Eastham C L, Lamping K G
Department of Internal Medicine, University of Iowa, Iowa City 52242.
Circulation. 1990 Jul;82(1):1-7. doi: 10.1161/01.cir.82.1.1.
Studies of the coronary circulation have divided vascular resistances into three large components: large vessels, small resistance vessels, and veins. Studies of the epicardial microcirculation in the beating heart using stroboscopic illumination have suggested that resistance is more precisely controlled in different segments of the circulation. Measurements of coronary pressure in different sized arteries and arterioles have indicated that under normal conditions, 45-50% of total coronary vascular resistance resides in vessels larger than 100 microns. This distribution of vascular resistance can be altered in a nonuniform manner by a variety of physiological (autoregulation, increases in myocardial oxygen consumption, sympathetic stimulation) and pharmacological stimuli (norepinephrine, papaverine, dipyridamole, serotonin, vasopressin, nitroglycerin, adenosine, and endothelin). Studies of exchange of macromolecules in the microcirculation using fluorescent-labeled dextrans have also identified the size of the small pore (35-50 A) in coronary microvessels that can be altered by myocardial ischemia. Studies of the coronary microcirculation have demonstrated that the control of vascular resistance is extremely complex, and mechanisms responsible for these heterogeneous responses need further examination.
大血管、小阻力血管和静脉。使用频闪照明对跳动心脏的心外膜微循环进行的研究表明，阻力在循环的不同节段受到更精确的控制。对不同大小动脉和小动脉中的冠状动脉压力进行测量表明，在正常情况下，冠状动脉总血管阻力的45%-50%存在于直径大于100微米的血管中。血管阻力的这种分布可通过多种生理（自动调节、心肌耗氧量增加、交感神经刺激）和药理刺激（去甲肾上腺素、罂粟碱、双嘧达莫、血清素、血管加压素、硝酸甘油、腺苷和内皮素）以非均匀的方式改变。使用荧光标记葡聚糖对微循环中大分子交换进行的研究也确定了冠状动脉微血管中小孔（35-50埃）的大小，其可因心肌缺血而改变。对冠状动脉微循环的研究表明，血管阻力的控制极其复杂，导致这些异质性反应的机制需要进一步研究。
