Thermoregulation in Telazol (CI-744)-anesthetized rhesus monkey (Macaca mulatta)

Seven Telazol (CI-744)-[Telazol is an experimental drug (Parke, Davis) composed of two ingredients in equal amounts by weight: tiletamine HCl, designated chemically as 2-(ethylamino)-2-(2-thienyl)cyclohexanone-HCl, and zolazepam HCl, designated as 4-(o-fluorophenyl)-6,8-dihydro-1,3,8-trimethylpyrazolo-3,4-e 1,4 diazepin-7(IH)-one monohydrochloride] anesthetized rhesus monkeys (Macaca mulatta) were exposed to ambient temperatures (Ta) of 15, 23, 29, 35, and 38 degrees C to evaluate the effect of this dissociative anesthetic agent on thermoregulation. Thermal equilibrium in both anesthetized and control animals at Ta 15 degrees C was through peripheral vasoconstriction and metabolic heat production (M); shivering increased M in the anesthetized group to 1.7 times the resting M of 41.4 W x m-2. Both groups at Ta 38 degrees C regulated body temperature by vasodilation and increased skin evaporative heat loss (Esk) due to sweating. Anesthetized animals increased Esk from 6.4 W x m-2 at Ta 29 degrees C to 32.5 W x m-2 at Ta 38 degrees C. Panting was not observed in either group. Effective tissue thermal conductance was lowest at Ta 15 and 23 degrees C (6.9 and 7.6 W x m2 x degrees C-1, respectively), and increased with Ta's above 23 degrees C (45.0 W x m-2 at Ta 38 degrees C). These results indicate that Telazol-anesthetized monkeys maintain thermal balance at ambient temperatures from 15 to 38 degrees C, and that Telazol induces little or no impairment of thermoregulation in rhesus monkeys.