Heterogeneity of the Hypoxic State in Perfused Rat Heart
Heterogeneity of the Hypoxic State in Perfused Rat Heart
复制标题
灌注大鼠心脏缺氧状态的异质性
DOI：
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发表时间：
1977
影响因子：
20.1
通讯作者：
Andjohn R. Williamson
中科院分区：
文献类型：
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作者：
C. Steenbergen;G. Deleeuw;C. Barlow;B. Chance;Andjohn R. Williamson
摘要用NADH荧光照相技术检测生理盐水灌流大鼠心脏的组织氧梯度。在高流量低氧中，冠脉流量保持不变，动脉血氧分压逐渐降低，在耗氧量显著减少之前，吸氧实际上已经完成。氧气供应不足导致缺氧区的明确模式。缺氧区的宽度为几百微米，比毛细血管间的距离大一个数量级。在低流量缺氧(缺血)中，动脉血氧分压保持在其控制值，而冠脉流量减少，也会形成缺氧区，模式与高流量缺氧相同。然而，在缺血时，当流出液氧分压显著大于零时，缺氧区形成。PH 7.3~6.9的呼吸性酸中毒导致血管扩张，pH 6.8以下的呼吸性酸中毒血管阻力显著增加。尽管对照的出水氧气压力只有轻微的变化，但出现了缺氧区。在高流量缺氧、缺血和酸中毒诱导的缺血中，当控制灌流条件恢复时，缺氧区消失。数据表明，在低氧状态下，组织的氧梯度非常陡峭，因此缺血和低氧导致缺氧组织中离散的异质区域被尖锐的区域包围，在这些区域中，氧气供应足以维持正常的线粒体氧化功能。在这些供氧量低于需氧量的状态下，冠脉血流似乎是在微动脉而不是毛细血管的水平上进行调节。
SUMMARY Tissue oxygen gradients were examined in the saline-perfused rat heart by NADH fluorescence photography. In high flow hypoxia, where the coronary flow was maintained and the arterial oxygen tension was gradually reduced, oxygen extraction was virtually complete before oxygen consumption was significantly diminished. Inadequate oxygen delivery resulted in a well defined pattern of anoxic zones. The anoxic zones were several hundred microns in width, an order of magnitude greater than intercapillary distances. In low flow hypoxia (ischemia), where the arterial oxygen tension remained at its control value and the coronary flow was diminished, anoxic zones also developed, following the same pattern as in high flow hypoxia. However, in ischemia, the anoxic areas developed while the effluent oxygen tension was significantly greater than zero. Whereas respiratory acidosis between pH 7.3 and 6.9 resulted in vasodilation, below pH 6.8 there was a marked increase in vascular resistance. Anoxic zones appeared despite only a slight change in effluent oxygen tension from the control. In high flow hypoxia, ischemia, and acidosis-induced ischemia, the anoxic zones disappeared when control perfusion conditions were restored. The data demonstrate that tissue oxygen gradients are very steep in the hypoxic state, so that ischemia and hypoxia result in discrete heterogeneous areas of anoxic tissue bounded by sharp areas where the oxygen supply is sufficient to maintain normal mitochondrial oxidative function. In these states in which oxygen delivery is less than oxygen demand, coronary perfusion appears to be regulated at the level of the arterioles rather than the capillaries.