Journal of Applied Physiology, Vol 47, Issue 1 87-90, Copyright © 1979 by American Physiological Society
Intestinal transport of hexoses in the rat following chronic heat exposure
M. Carpenter and X. J. Musacchia
The effect of 3 wk heat exposure (Ta 34 degrees C) on intestinal weight and
intestinal absorption of D-glucose and D-galactose in vitro was examined in
the rat. Intestinal dry weight was reduced with heat exposure compared to
both ad libitum and pair-fed animals at Ta 22 degrees C. Intestinal tissue
water was elevated after pair feeding but not heat exposure; extracellular
(inulin) space was similar in the three groups. Mucosal uptake of glucose
per gram wet weight in an everted sac preparation was unchanged compared to
pair-fed animals, but serosal transfer was increased. Intestinal metabolism
of glucose was decreased with heat exposure. Galactose accumulation with 30
min incubation was increased in intestinal rings from both heat-exposed and
pair-fed animals. This increase is likely to be related to the reduction in
ring size present in the groups with reduced food intake. Vmax and apparent
Km for galactose transport were unchanged. Our results indicate that
despite a reduction in intestinal weight following heat exposure, the
ability of the intestine to transport hexoses per gram remains relatively
stable. Alterations of hexose transport appear to be related to altered
glucose metabolism and not altered transport capacity. Differences in
intestinal weight and glucose utilization between pair-fed and heat-exposed
animals suggest that the intestinal response to chronic heat exposure is
not solely a function at the amount of food consumed. However, the
alteration of more than one variable in pair feeding makes interpretation
complex.
