RoIe of Adrenaline and Noradrenaline in Chemical Regulation

HSIEH, A. C. L. AND L. D. CARLSON. Role of adrenaline and noradrenuline in chemical regulatz’mt of heat floduction. Am. J. Physiol. 190(2) : 243-246. 1957.-Cold-adapted spinal rats showed a greater increase in oxygen consumption following adrenaline than did warm-adapted ones. Thyroidectomy reduced the responses of warmand cold-adapted spinal rats to about the same levels. In curarized rats, exposure to cold resulted in a greater increase in oxygen consumption and lower blood glucose concentration than adrenaline injection did. While noradrenaline had little effect in warmadapted rats, there was a marked calorigenic response in cold-adapted rats. The results indicate, in addition to the increased calorigenic action of adrenaline in cold-adapted rats, a greatly increased calorigenic response to noradrenaline. The possibility that noradrenaline may be the mediator in chemical regulation of heat production is discussed. C OTTLE and Carlson (I), by exposing cugenie effect in rats (5) and guinea pigs (6), rarized rats to cold, have demonstrated Hsieh, Carlson and Gray (7) observed that in that cold-adapted rats have an increased cold-adapted rats noradrenaline is more effecability to produce heat by chemical regulative than adrenaline in preventing the fall in tion. The increased calorigenic effect of adoxygen consumption caused by hexamethonrenaline in cold-adapted rats (2), forms an attractive explanation for this increased potential for chemical regulation. Since the term ‘chemical regulation’ has been used to imply the production of heat by means other than muscular contraction, the activity which follows the administration of adrenaline to unanesthetized rats (3, 4) complicates application of such results to this question. Therefore, in our experiments, the effects of adrenaline have been tested under conditions of minimal muscular activity after spinal transection or curarization. Changes in oxygen consumption and blood glucose concentration were the indices used. Although noradrenaline has little caloriReceived for publication January 17, 1957~ 1 This research was supported in part by the U. S. Air Force under Contract No. AF 18(600)-1467, monitored by the Alaskan Air Command, Arctic Aeromedical Laboratory. 2 Present address: Dept. of Physiology, University of Hong Kong, Hong Kong. ium. This finding suggests that noradrenaline may play an important part in the response of cold-adapted rats to cold. The metabolic effects of adrenaline, noradrenaline and cold exposure have therefore been compared.