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

摘要

(1) Measurements of VO2 and T-b daily rhythms in T. nigricauda were conducted. (2) Three different effects on VO2 and Tb 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.