Journal of Applied Physiology, Vol 53, Issue 5 1171-1174, Copyright © 1982 by American Physiological Society
Heat-stressed rat: effects of atropine, desalivation, or restraint
R. W. Hubbard, C. B. Matthew and R. Francesconi
Heat-stressed rats thermoregulate behaviorally by spreading saliva onto
body surfaces and thus lose body water through evaporative cooling. Prior
to exploring the role of dehydration in our rat heatstroke model, we sought
to compare the abilities of physical restraint, surgical desalivation,
and/or atropine to increase the rate of body heat storage by inhibiting
body water loss and evaporative cooling during heat exposure. In these
experiments, male Sprague-Dawley rats were stressed at an ambient
temperature of 41.5 degrees C either in their own cages or in a restraining
device until a rectal temperature of 42.6 degrees C was attained.
Unrestrained control rats heat-stressed at this temperature lost
approximately 8% of body weight (water) during a 258-min exposure. Physical
restraint or desalivation reduced both the exposure time and body weight
loss by about 72%. Surgically desalivated, heat-stressed rats were observed
to engage in voluntary urine-spreading behavior. Maximal heat storage and
therefore maximal reduction in exposure time and inhibition of body weight
loss to less than 10% of control values were achieved by either physical
restraint plus desalivation or by a 500-micrograms dose of atropine.
