Inferring the metabolic rate of bone

Abstract

The bone organ is poorly represented in comparative research on mammalian mass-specific metabolic rates. As a first order attempt to remedy this, from the literature we collected mass-specific metabolic rates for all major organs except for the bone organ, and by subtraction infer the rate for the bone organ. The scaling relationships are given of each whole-organ mass-specific metabolic rate and of the relationship between whole-organ metabolic rate and body mass. Scaling of the lung, adipose depot and bone organ with body mass is higher than would be expected by ¾ power scaling. We interpret the similar scalings of bone and the adipose depot in light of their evolved regulation of whole-body metabolism. We also briefly examine the supra-¾ power scaling of the lung as well as the independence of the mass-specific metabolic rate of the heart from body mass. The bone organ exhibits relatively high energy expenditure with increasing body size. The bone marrow and its medullary adipocyte store may be responsible for engendering the greater share of the bone organ's energetic cost.