Journal of Applied Physiology, Vol 46, Issue 4 662-668, Copyright © 1979 by American Physiological Society
Catecholamines in dogs during cold adaptation by repeated immersions
A. Therminarias, M. F. Chirpaz, A. Lucas and M. Tanche
Dogs were immersed in cold water 1 h/day for 30 consecutive days. During
the first immersion, oxygen uptake increased approximately sevenfold and
colonic temperature decreased; a large increase in plasma epinephrine and
norepinephrine concentrations was found; plasma glucose, lactic acid, and
free fatty acid (FFA) concentrations were also increased. An adaptative
response to cold was evidenced during the 10th immersion by a further
increase in oxygen uptake and a reduction in the fall of colonic
temperature; plasma epinephrine, glucose, and lactic acid were diminished
whereas FFA were higher. Consequently 10 h spent in cold are sufficient to
induce an improved capacity for heat production. An enhanced ability to
produce nonshivering thermogenesis mediated by epinephrine or
norepinephrine is not obvious because after the 30th immersion no enhanced
calorigenic response to epinephrine or norepinephrine infusion was found.
In dogs mechanisms other than norepinephrine-enhanced sensitivity might be
involved in this kind of cold adaptation.
