title: Is resting muscle oxygen uptake controlled by oxygen availability to cells?
abstract: To estimate oxidative capacity of noncontracting rat skeletal muscle, the isolated gracilis muscle was perfused at various high flow rates with high-PO2 (88 kPa) saline-albumin solution and simultaneously perifused at either low (6.3 kPa) or high PO2 in a calorimeter at 28 degrees C. Under low-PO2 perifusion, specific O2 consumption and heat production rates (MO2 and E, respectively) were flow-rate dependent. E values were all larger than those obtained on blood-perfused preparations at 28 degrees C. MO2 reached 0.47 mumol.min-1.g muscle-1 and E reached 4 mW/g. Normalized to 36 degrees C by means of activation energies determined from 30 and 36 degrees C measurements on nonperfused gracilis strips, these maxima correspond to three times the largest MO2 measured by other authors in blood-autoperfused gracilis. Increasing perifusion PO2 from 6.3 to 88 kPa sharply decreased MO2. These results confirm that MO2 of blood-perfused skeletal muscles in vitro (and a fortiori in vivo) is kept much below its maximum for a noncontracting organ; they also suggest that this maximum MO2 is not necessarily an effect of unphysiologically high PO2 in the tissue cells.
authors.affiliation: Department of Physiology, Centre Médical Universitaire, Geneva, Switzerland.
authors.forename: A E
authors.initials: AE
authors.lastname: Chinet
authors.forename: J
authors.initials: J
authors.lastname: Mejsnar
mesh_terms: D000818:Animals; D001682:Biological Availability; D001769:Blood; D001833:Body Temperature Regulation; D066298:In Vitro Techniques; D008297:Male; D009132:Muscles / Q000166:cytology / Q000378:metabolism*; D010100:Oxygen / Q000493:pharmacokinetics*; D010101:Oxygen Consumption; D010313:Partial Pressure; D010477:Perfusion; D051381:Rats; D011919:Rats, Inbred Strains; D012146:Rest; D013696:Temperature
chemical_list: D010100:Oxygen