Journal of Applied Physiology, Vol 42, Issue 5 694-698, Copyright © 1977 by American Physiological Society
Changes in plasma glucose, FFA, corticosterone, and thyroxine in He-O2-induced hypothermia
L. C. Wang and R. E. Peter
Unanesthetized, male rats were exposed to normal air (NA), or NA and a 4
h-exposure of He-O2 (79% helium, 21% oxygen) at ambient temperature (Ta) of
22 or - 10 degrees C. Blood samples from each individual were taken from a
chronically implanted carotid cannula at 1) preexposure, 2) during
exposure, 3) 2.5 h after exposure, and 4) 19-20 h after exposure. Exposure
to He-O2 at 22 degrees C caused an increase in plasma free fatty acids
(FFA) and corticosterone of 45% and 49%, respectively, with little change
in plasma glucose and thyroxine. Exposure to He-O2 at 10 degrees C for 3 h
invariably induced hypothermia with body temperature (Tb) decreased to 23.7
+- 0.5 degrees C (N = 10). During hypothermia, plasma glucose, FFA, and
corticosterone were significantly higher (P LESS THAN 0.05) than those at
preexposure and those after exposure to NA at -10 degrees C. During
spontaneous recovery from hypothermia, at Ta = 19 degrees C and NA,
glucose, corticosterone, and thyroxine returned to normal, but FFA remained
significantly higher than at preexposure. The ability of animals to rewarm
spontaneously from hypothermia and the quick return of metabolic substrates
and hormones to normal after rewarming indicates the preservation of
regulatory mechanisms for metabolism at depressed Tb when hypothermia is
induced by He-O2 and cold.
