Watanabe S, Buffington C W, Moresea G
Department of Anesthesiology and Critical Care Medicine, University of Pittsburgh, Pennsylvania 15213.
Am J Physiol. 1995 Mar;268(3 Pt 2):H1276-83. doi: 10.1152/ajpheart.1995.268.3.H1276.
We have determined the transmural distribution of myocardial flow and ischemia during endothelin (ET-1) infusion and compared these results with the effects of mechanical stenosis. In anesthetized pigs, coronary flow was reduced 15, 30, and 50% from baseline values with a mechanical stenosis (n = 7) or increasing doses of intracoronary ET-1 (n = 8). The inner-to-outer flow ratio decreased with decreasing total flow during mechanical stenosis, and S-T segment elevation occurred predominantly in the subendocardium. In contrast, the inner-to-outer flow ratio exceeded 1.0 and actually increased during ET-1 infusion. ET-1 limited the electrocardiographic evidence of subendocardial ischemia and attenuated contractile dysfunction compared with mechanical stenosis at the same coronary flows, even though lactate flux was similar. Reactive hyperemia was retained with ET-1, even when coronary flow was reduced enough to cause lactate production. These results demonstrate a more uniform transmural distribution of flow caused by microvascular constriction than by a large-vessel stenosis.
我们已经确定了内皮素（ET-1）输注期间心肌血流和缺血的透壁分布，并将这些结果与机械性狭窄的影响进行了比较。在麻醉的猪中，通过机械性狭窄（n = 7）或增加冠状动脉内ET-1剂量（n = 8），冠状动脉血流从基线值分别降低了15%、30%和50%。在机械性狭窄期间，随着总血流量的减少，内膜与外膜血流比值降低，ST段抬高主要发生在心肌内膜下。相比之下，在ET-1输注期间，内膜与外膜血流比值超过1.0，实际上还会增加。与相同冠状动脉血流量下的机械性狭窄相比，ET-1限制了心肌内膜下缺血的心电图证据，并减轻了收缩功能障碍，尽管乳酸通量相似。即使冠状动脉血流减少到足以导致乳酸产生，ET-1仍能保留反应性充血。这些结果表明，微血管收缩引起的血流透壁分布比大血管狭窄引起的更均匀。
