Journal of Applied Physiology, Vol 51, Issue 6 1428-1432, Copyright © 1981 by American Physiological Society
Glycogen and nonspecific adaptation to cold
J. LeBlanc and A. Labrie
Exposure to moderate cold for a few weeks causes adaptation through the
development of nonshivering thermogenesis primarily in the brown adipose
tissue. Exposure to severe cold by repeated short exposures also causes
adaptation but by mechanisms that seem to be different. These latter
results were confirmed in mice. It was also found that this type of
adaptation is nonspecific because it can be produced by other stresses such
as swimming or fasting. Simultaneous determinations of glycogen in the
liver and soleus and tibialis muscles indicated a possible role for this
substrate in cold resistance. Repeated cold exposure (8 times at -15
degrees C for 10 min), swimming for 3 h, or fasting for 48 h--all reduced
the glycogen stores when measured immediately after the stress. However,
the levels of glycogen were significantly increased above the initial
values (P less than 0.01) when the determinations were made 24 h later.
Cold tolerance measured by resistance to hypothermia at -5 degrees C was
improved only when the test was done 24 h after the stress had taken place.
Thus, cold resistance, as described in this study, is nonspecific and our
results suggest that glycogen stores could serve as a rate-limiting
substrate.
