AJP - Regulatory, Integrative and Comparative Physiology, Vol 245, Issue 1 76-R82, Copyright © 1983 by American Physiological Society
Thermoregulatory responses to central injections of excess calcium in monkeys
C. V. Gisolfi, P. T. Wall and W. R. Mitchell
In unanesthetized monkeys (4-8 kg), artificial cerebrospinal fluid (ACSF)
containing excess (greater than 1.3 mM) amounts of Ca2+ was infused at 20
microliters/min for 5 min into the cerebral ventricles. Core and skin
temperatures, respiratory gas exchange, heart rate, and sweat rate were
monitored. At 22 degrees C, intracerebroventricular infusions of 13-39 mM
Ca2+ produced a dose-related hypothermia associated with a dose-related
fall in metabolic rate and heart rate and a rise in average skin
temperature. General body sweating was not initiated, and respiratory water
loss was unaffected; however, exercise activated sweating and elevated it
from 0.05 to 0.22 mg X (cm2 X min)-1. At 35 or 40 degrees C, infusion of 26
mM Ca2+ failed to influence ongoing general body sweating; however,
subsequent exercise increased sweat rate by 63%. Heart rate was unaffected.
At 15 degrees C metabolic rate increased 50%. After infusing 26 mM Ca2+,
metabolism decreased 6% and core temperature declined 0.8 +/- 0.24 degrees
C. Skin temperatures continued to fall, heart rate fell, and sweating was
not initiated. In contrast, infusing ACSF increased metabolism 11% and core
temperature fell only 0.18 +/- 0.14 degrees C. The inability of exogenous
Ca2+ to 1) initiate sweating at 22 degrees C, 2) elicit vasodilation at 15
degrees C, 3) initiate or stimulate sweating at 35 or 40 degrees C, or 4)
lower core temperature at 35 or 40 degrees C argues against a set-point
function for this cation.
