Effects of adrenergic blockade on the daily rhythms of body temperature and oxygen consumption of the black-tailed tree rat (Thallomys nigricauda) maintained under different photoperiods

(1) Measurements of VO₂ and T_b daily rhythms in T. nigricauda were conducted. (2) Three different effects on VO₂ and T_b were assessed: alpha and beta blockade, time of the day, and photoperiod regime. (3) Results show that in T. nigricauda, the response of T_b and VO₂ differs significantly under the different photoperiod regimes. Rats acclimated to 16L:8D increased T_b values as a response to beta blockade, while alpha blockade caused a decrease in T_b. (4) VO₂ values of T. nigricauda acclimated to 11.5L:12.5D responded differently to alpha and beta blockade. It can be assumed that the thermoregulatory responses with beta blockade are through a decrease in heat production, rather than through heat dissipation. However, in the case of alpha blockade, it may be assumed that heat dissipation, through vasodilation, is the cause for the decrease in T^b values.