Critical O2 delivery in rat brain.

Abstract

As O2 delivery (DO2) of whole body,1,2 intestine,3,4 liver,5 or skeletal muscle6 is progressively decreased in anesthetized animals, O2 consumption (VO2) is initially maintained constant via increased O2 extraction by the tissues (O2 supply independence). However, below a critical threshold DO2 value (DO2c), VO2 of these organs decreases in proportion to DO2 (O2 supply dependence). More importantly, dysoxia (i.e. O2 demand that exceeds O2 supply)7 appears to commence at the onset of liver O2 supply dependence, as reflected by the simultaneous decrease in VO2 and increase in hepatic mitochondrial reduction.5 Accordingly, it tentatively appears that dysoxia may be identified, in liver at least, by the DO2c inflection of a biphasic VO2- DO2 relation.KeywordsCerebral Blood FlowMean Arterial PressureExtraction RatioSuperior Sagittal SinusImmobilization StressThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.