The interaction of shivering and non-shivering thermogenesis in deer mice ( Peromyscus maniculatus)

Abstract

1. Following cold acclimation, adult deer mice ( Peromyscus maniculatus) were anesthetized and treated with the β-adrenergic blocking agent, propranolol, at an ambient temperature of 25°C in order to determine whether shivering substitutes for non-shivering thermogenesis. Oxygen consumption, muscular activity and rectal temperature were measured. 2. Following propranolol administration at 25°C, only 3 of 10 animals shivered; and, of those, only one increased metabolism significantly. All treated animals showed a fall in rectal temperature (mean of about 3°C) compared to sham preparations. 3. Experiments performed at 16°C showed that the mice can shiver following β-adrenergic blockade. 4. These results show that shivering thermogenesis does not substitute for non-shivering thermogenesis at 25°C and suggest that a lower threshold temperature is necessary to induce shivering than non-shivering thermogenesis.