Intracellular Po ₂ and Its Regulation in Resting Skeletal Muscle of the Guinea Pig

Abstract

Intracellular Po 2 in the gracilis muscle of lightly anesthetized guinea pigs was measured by means of an O 2 microelectrode to see (a) whether the Po 2 was low enough that it might limit O 2 consumption, and (b) whether it would increase with high O 2 breathing. The resting cell membrane potential was used to localize the electrode tip. Of 184 cells tested in 26 animals, 70 cells had a Po 2 of less than 1 mm Hg. Mean intracellular Po 2 was about 4 mm Hg. When 100% O 2 or 98% O 2 -2% CO 2 was administered while the electrode was in a cell, 60 of 89 cells tested (20 animals) showed no change in Po 2 . In the other 29 cells, the Po 2 increased by 5% or more. We have concluded that blood flow in resting skeletal muscle in the anesthetized guinea pig is regulated so as to maintain a low Po 2 -low enough that it could limit O 2 consumption.