Journal of Applied Physiology, Vol 54, Issue 4 896-900, Copyright © 1983 by American Physiological Society
Sympathoadrenal responses to cold and ketamine anesthesia in the rhesus monkey
M. A. Kolka, R. S. Elizondo and R. P. Weinberg
The effect of cold exposure on the sympathoadrenal system in primates was
studied with and without ketamine anesthesia in eight adult rhesus monkeys.
Each monkey was placed in a primate chair at a thermoneutral temperature
(25 degrees C) for 1 h (control) followed by cold exposure (12 degrees C)
for 3 h or placed in a circulating water bath (28 degrees C) to induce a
decrease in core temperature (Tre) to 35 and 33 degrees C. Plasma
catecholamines were analyzed by high-pressure liquid chromatography with
electrochemical detection (60-65% recovery, coefficient of variation =
15%). The 3-h cold exposure was associated with a 175% increase above
control levels of norepinephrine (NE) and a 100% increase in epinephrine
(E). Decreases were evident in Tre (0.5 degree C), mean skin temperature
(Tsk, 5.5 degrees C), and mean body temperature (Tb, 2.0 degrees C).
Continuous infusion of ketamine (0.65 mg . kg-1 . min-1) resulted in no
change in the plasma levels of NE and E from the control levels. Tre, Tsk,
and Tb all showed greater declines with the addition of ketamine infusion
to the cold exposure. Water exposure (28 degrees C) under ketamine
anesthesia resulted in a drop in Tre to 33 degrees C within 1 h. Plasma
levels of NE and E were unchanged from control values at Tre of 35 and 33
degrees C. The data suggest that the administration of ketamine abolished
both the thermoregulatory response and the catecholamine response to acute
cold exposure.
