Effect of Low Temperature and Work on Blood Lactic Acid in Deer Mice

Abstract

Except occasionally during intense shivering, blood lactic acid of resting deer mice (Peromyscus maniculatus gracilis, Le Conte) remained within normal limits at temps. from 30[degree]C. to -27[degree] C, even though the O2 consumption at the lowest temp. was increased to 7 times that observed at 30[degree] C. Normal lactate values were also found at the point of death in the cold. On the other hand, a pronounced increase in lactate was found in running mice at 30[degree] C. when the O2 consumption had increased only 3-5 times the resting rate. After the same amt. of work, lactate levels were approx. equal at room temp. (22[degree] C.) and in the cold (0[degree]C). The observations suggest differences in the site of energy release during work and cold exposure, and various hypotheses, including the contribution of non-muscular tissue, are discussed.