Metabolic, ventilatory, and hygric physiology of a South American marsupial, the long-furred woolly mouse opossum

Abstract

Abstract The physiology of the long-furred woolly mouse opossum (Micoureus paraguayanus) conformed to that of other marsupials. Body temperature at thermoneutrality (all values reported as mean ± SE) was 33.3°C ± 0.3°C and basal metabolic rate was 0.760 ± 0.074 ml O2 g−1 h−1. Opossums were thermolabile at low ambient temperature (Ta) but still maintained a considerable differential between body temperature and Ta, with an increase in metabolic heat production as Ta decreased. This was accommodated by an increase in minute volume, mediated by an increase in both respiratory frequency and tidal volume at low Ta. Basal respiratory frequency was 34.2 ± 3.8 breaths/min and tidal volume was 1.62 ± 0.28 ml; minute volume was 53 ± 7 ml/min. Oxygen extraction remained constant at 13.6% ± 1.1%. Wet thermal conductance was high (0.338 ± 0.091 ml O2 g−1 h−1 °C−1; 185% of predicted) but conformed statistically to that of other marsupials. A positive relationship existed between ambient temperature and evaporative wate...