The role of the body mass: body surface ratio in thermo-regulatory responses to cold, hypoxia, and hypercapnia in new-born, adult, and aged guinea pigs.

The relationship between body weight (BW) and the changes in colonic temperature (deltaTc) was analyzed in newborn, adult, and old guinea pigs. No correlation could be demonstrated between BW and, deltaTc in response to cold with the exception of the 10 to 20 day-old group. In hypercapnia statistically significant or almost significant coefficient were obtained in three groups, showing--as expected--that the fall in Tc tended to decrease with increasing BW. In hypoxia a statistically significant coefficient was obtained in the young adult group, demonstrating that--contrary to expectation--the fall in Tc tended to be greater with increasing BW.