Oxygen tension (PO2) profiles within unperfused hamster retractor muscles were obtained at 25, 30, and 37° by using sharpened, recessed oxygen microelectrodes. The microelectrode was driven vertically into freshly excised muscle lying on a flat, impermeable boundary inside a diffusion chamber. Intramuscular PO2 profiles were measured as a function of electrode depth in 10-μm steps during both inward and outward penetrations when the upper surface of the muscles was exposed to humidified gases containing 10, 21, 50, and 100% O2. The ratio of the O2 consumption (M) to the O2 permeability (K, Krogh diffusion coefficient = Dα, diffusion coefficient-solubility product) was estimated by curve-fitting the experimental steady-state distribution of O2 through muscles to the analytic solution of the diffusion equation assuming that M obeys zero-order kinetics and K is constant, uniform, and independent of PO2. The ratios of M/K were independent of temperature and were found to be independent of surface PO2 and muscle thickness. The average value of M/K was 3.9 ± 0.45 (SE; n = 30) x 105 mm Hg/cm2, which is consistent with that estimated from previous measurements of M and D using different non-steady-state techniques (Bentley et al., 1993). These results are consistent with other in vitro O2 consumption measurements (Sullivan and Pittman, 1984) and do not provide evidence for nonclassical respiratory activity in resting mammalian skeletal muscle.
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine
- Cell Biology