Total metabolism and summated tissue respiration in relation to body size

Abstract

Total metabolism and summated tissue respiration in relation to body size. Recording weight-specific total body metabolism of the mouse at two ambient temperatures (22.5 °, 350 C) and plotting the resulting data on a double logarithmic grid revealed a cyclic allometry with a positive constant between 1.3 and 5 g body weight (cycle I) and a negative constant between 5 (or 7) and 23 g (cycle II). Similar cycles concerning the weight-allometry of the mass of several organs (brain, heart, liver, skin) and the tissue respiration of brain, liver, intestine and kidneys are statistically significant. If the summated tissue respiration is determined over the entire body size range --by summing up tissue respiration for several individual body weights and calculating the regression lines-two cycles are, again, observable; their slopes cannot be distinguished statistically from those of the cycles of total body 02-uptake at 35 ° C. Its intensity, however, is considerably lower than that of the directly measured total body metabolism. If certain corrections are applied (inclusion of skin respiration and extrapolation of respiration in vitro to tO the intensity of summated tissue respiration as well as its slope coincide well with the BMR obtained from literature.