AJP - Heart and Circulatory Physiology, Vol 253, Issue 5 1120-H1126, Copyright © 1987 by American Physiological Society
Arteriolar oxygen reactivity: where is the sensor?
W. F. Jackson
Department of Physiology, Medical College of Georgia, Augusta 30912.
The hypothesis that arterioles are intrinsically sensitive to oxygen was
tested by comparing arteriolar diameter responses with local and global PO2
changes in superfused hamster cheek pouch preparations. Local PO2 changes
were produced by microapplication of fluid onto the surface of occluded or
unoccluded aparenchymal arterioles or by cannulation and perfusion of
arterioles in situ. Global changes refer to PO2 changes in the superfusate
flowing over the entire preparation. Local, effective PO2 changes had no
significant effect on arteriolar diameters. In contrast, global PO2 changes
produced significant, reproducible changes in diameter. These observations
do not support the hypothesis that arterioles are intrinsically oxygen
sensitive, unless the oxygen-sensitive sites are distributed sparsely along
the arteriolar tree. The data are consistent with oxygen sensors located
either in vessels downstream from 15-micron arterioles (in terminal
arterioles, capillaries, or venules) or in the parenchyma. The data also
suggest that these sensors detect changes in PO2 and then initiate
responses that can be conducted along the vasculature to an arteriole
distant from the sensor.
