Oxygen consumption of the isolated carotid body tissue (cat).

The oxygen consumption of the isolated carotid body tissue measured in microchambers (volumes 12 and 20 mul) was 0.0051 mul O2/mg wet weight-min for an average of 54 measurements at 22 +/- 1 degree C, if the calculation was based on the oxygen pressure decrease of the surrounding medium measured polarographically in the range from 120 to 50 torr. It is bound to the presence of exogenous substrate and almost completely inhibited by antimycin but not significantly altered by addition of EGTA (4-16 mM) or Ca2+ (2 mM). Measurements performed at higher oxygen pressures (300 to 100 torr) in the medium show that the oxygen consumption of isolated carotid body tissue is independent of oxygen pressure at these high oxygen pressures. The findings obtained under the above conditions argue in favor of a mitochondrial oxygen consumption. The results are discussed with regard to data obtained with needle electrodes in the perfused organ.