Influence of Cold Upon the Metabolism and Body Temperature of Wild Rats, Albino Rats and Albino Rats Conditioned to Cold

Publisher Website
Google Scholar
Abstract
The effect of varying environmental temperatures on rats previously conditioned to cold has in the past been studied chiefly in relation to metabolism and body temperature during exposure to air temperatures of 0[degree]-30[degree]C. The present study concerned the metabolic rates (O2 consumptions) and body temperatures of "normal" albino rats (maintained at 30[degree]), cold-conditioned albino rats (maintained at 5[degree]), and wild rats captured in winter at Fairbanks, Alaska, and maintained in an open animal house. Metabolic rate was determined in an open circuit respirometer, O2 and CO2 being measured by Scholander 0.5 cc gas analyzer. Body temperature was measured by iron-constantan thermo-couples 8 cm in the rectum. No attempt was made to maintain basal conditions. After 2.5 hours exposure to low temperature, maximal metabolic rate for cold-conditioned white rats was at -30[degree]; for normal white rats at -10[degree]. This difference reflected ability of cold-conditioned rats to maintain higher metabolic rates at all temperatures. Wild rats survived lower temperatures and could increase metabolism 4.5-6 times over basal level, compared to 3 times for white rats. Wild rats responded to low temperature in a manner normal to wild animals of cold climate, while white rats with BMR 60% higher than that of animals of their size, showed deviations from normal pattern. Body temperature in cold-conditioned white rats showed no appreciable fall after 2.5 hour exposure to -10[degree], while normal rats required 10[degree]. These differences corresponded to those in metabolism curves, except that critical points of body temperatures were higher, probably due to immobilization by thermocouples. Body temperatures of cold-conditioned white rats were slightly lower than those of the normal rats.

This publication has 6 references indexed in Scilit: