Journal of Applied Physiology, Vol 41, Issue 2 180-184, Copyright © 1976 by American Physiological Society
PO2 in the carotid body perfused and/or superfused with cell-free media
W. J. Whalen and P. Nair
We measured with a micro-O2 electrode the tissue PO2 (PtO2) in the cat
carotid body (CB) to see whether it was adequately oxygenated when perfused
or superfused with artificial, cell-free (c-f) solutions (pH = 7.4; temp =
35-38 degrees C). To obtain a relative measure of O2 consumption (VO2), we
also measured the rate of disappearance of O2 following stoppage of the
blood flow, and compared these disappearance curves with those during
stoppage of the c-f perfusion solutions. In 14 cats normal (blood
perfusion) PtO2 values ranged from 10 to 104 mmHG; chi = 72 +/- 4 (SE--as
used throughout). During 3 h of c-f perfusion with air-equilibrated Locke's
solution, PtO2 ranged from 62 to about 160 mmHg; chi = 133 +/- 4. When
perfused with Fay's equilibrated with 98% O2-2% CO2 no PtO2 values in the
CB were below 300 mmHg (4 cats). In eight additional cats the CB was
cleared of blood then superfused with saline equilibrated with 50% O2
underneath and air-equilibrated saline over. Less than 5% of the PtO2
values found were below 5 mmHg. We conclude that most studies on the
artificially perfused or superfused CB cannot be invalidated on the basis
that the preparations were hypoxic. O2 disappearance curves taken during
blood perfusion were significantly faster than during c-f perfusion
indicating a marked reduction in VO2 with c-f perfusion.
