Brown fat, thermogenesis and physiological birth in a marsupial.

Resting oxygen consumption corrected for body size, increased in young marsupials (Bennett's Wallaby) with body weights of 50-400 g. Up to 250 g body wt injections of noradrenaline caused either a fall or no change in metabolic rate, but above this age a significant rise was evoked. This age also corresponded to a rapid increase in growth rate and identification of active brown adipose tissue, assessed from electron microscopy and measurements of purine nucleotide binding to isolated mitochondria.