Influence of temperature on oxygen diffusion in hamster retractor muscle

A mathematical analysis by Popel et al. [Am. J. Physiol. 256 (Heart Circ. Physiol. 25): H921-H924, 1989] of in vivo data on arteriolar O-2 loss suggested that Krogh's diffusion coefficient (KO2 = alpha . DO2, where DO2 is the O-2 diffusion coefficient and alpha is the tissue O-2 solubility) in vivo could be an order of magnitude larger than that calculated from DO2 values measured in vitro at 22 degrees C and extrapolated to 37 degrees C. In this study, to eliminate potential extrapolation errors, we used a miniature hyperbaric chamber with 1-2 atm of O-2 to maintain tissue oxygenation and allow DO2 measurements directly at 37 degrees C while using a non-steady-state technique. The need for metabolic poisons that had been required by earlier experimental techniques was thereby eliminated. DO2 measured directly at 37 degrees C (2.42 . 10(-5) cm(2)/s) and the increase with temperature of DO2 between 30 and 41 degrees C (4.61%/degrees C) were unexpectedly higher than the values we found at lower temperatures. Oxygen consumption was also higher than expected at 37 degrees and 40 degrees C. An analysis of the activation energy for DO2 suggests that at higher temperatures there is a change in the diffusion pathway from that existing at lower temperatures, perhaps caused by phase transitions in the lipid membranes.