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 VO(2) and T(b) daily rhythms in T. nigricauda were conducted. (2) Three different effects on VO(2) 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 VO(2) 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) VO(2) 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.
School of Education Oranim, University of Haifa, P.O. Kiryat, Tivon, Israel
A
A
Haim
C T.
CT
Downs
J
J
Raman