TEMPERATURE-DEPENDENCE OF OXYGEN DIFFUSION AND CONSUMPTION IN MAMMALIAN STRIATED-MUSCLE

This study investigated the effect of temperature on the oxygen diffus ion coefficient (DO2) of hamster retractor muscle from 11 to 37-degree s-C. DO2 was measured using a non-steady-state technique, whereas musc le O2 consumption (VO2) was estimated after steady state was reached. DO2 was 0.84 +/- 0.04 x 10(-5) cm2/s at 11-degrees-C and rose exponent ially to 2.41 +/- 0.19 x 10(-5) cm2/s at 37-degrees-C, producing a tem perature coefficient for DO2 of 4.60%/degrees-C for this temperature r ange. To measure DO2 directly at 37-degrees-C, it was necessary to inh ibit tissue VO2 with Amytal. The DO2 measurements made at 37-degrees-C were significantly higher than previously reported values, which had been based on extrapolations from lower temperatures (6). Further anal ysis suggests a possible transition in the diffusion pathway between 2 3 and 30-degrees-C, resulting in a DO2 higher. than that previously ex pected. This larger DO2, together with a recently published value of o xygen solubility (alpha) (21), results in an in vitro Krogh's diffusio n coefficient (KO2) that is 2.4 times larger than that previously repo rted (24) and therefore significantly reduces an order of magnitude di screpancy between in vitro and estimated in vivo KO2 values (24). Musc le VO2 was 0.35 ml O2 . min-l . 100 g-1 at 11-degrees-C and increased with temperature, resulting in an activation energy of the rate-limiti ng reaction from the Arrhenius equation of -10.5 kcal/mol between 11 a nd 30-degrees-C.