The scaling of maximal oxygen consumption and pulmonary dimensions in small mammals

Abstract

This report has reexamined the relationship between standard and maximal rates of oxygen consumption (V̇ O2 std and V̇ O2 max) and pulmonary surface area in mammals whose weights extend over the lower half of the total log weight range in mammals. For combined groups of wild and laboratory animals with body weights of 2—3700 g, the following equations pertain: V̇ O2 std (ml·min −1) = 0.0602· W 0.727; V̇ O2 max (ml·min −1) = 0.499· W 0.678; alveolar surface area S a (m 2) = 0.00406· W 0.888. The ratio of V̇ O2 max/V̇ O2 std, or the factorial aerobic scope, is nearly constant over this weight range at approximately 6.6 (range 5.8–7.1). In view of this finding, earlier studies relating S a or pulmonary diffusion capacity to V̇ O2 std are still appropriate models for pulmonary constraints on metabolic rate. The data summarized here suggest that, at least for wild species of mammals, pulmonary diffusion capacity may limit V̇ O2 max.