Changes in Cerebral Oxygen Tension and Red Cell Content on Sensory Stimulation

Abstract

According to current studies, the cerebral cortical circulation shows well developed “oxygen autoregulation” to the extent that local increases in oxygen consumption in the sensory cortex produced by peripheral stimulation are accompanied by increases in blood flow so finely adjusted that no local changes in Po₂ can be detected (Leniger-Follert and Hossmann, 1979). If indeed there is no local fall in Po₂, then hypoxia cannot be the signal for increased blood flow, and it is necessary to postulate some other mechanism similar to the old “axon reflex” to account for this type of autoregulation. However, if the signal involves a change in Po₂ in a very small volume, perhaps a single neurone and occurring for a period of less than one second, then Polarographic electrodes might not have sufficient temporal and spatial resolution to measure this. With our T. V. system we can measure changes in oxygen tension and microregional red cell mass in cylinders of tissue of 10 um diameter and approximately 150 urn deep with a time resolution of 33 msecs.