The response in heat production, plasma catecholamines, and body temperature of burned rats to hypothalamic temperature displacement.
Rats, with the preoptic anterior hypothalamus implanted with two thermodes and a thermocouple reentry tube, had simultaneous direct and indirect calorimetry performed [during the ninth to eleventh postburn day interval] at ambient temperatures of 22 degrees and 28 degrees C. During calorimetry, blood was drawn at baseline and near the end of each period of displacement of the preoptic anterior hypothalamus temperature for catecholamine assay. Cooling the preoptic anterior hypothalamus resulted in a significant increase in heat production and plasma epinephrine and norepinephrine concentrations for both burn and control groups at 22 degrees C and 28 degrees C (p < 0.05 for all comparisons). Heat production demonstrated consistent negative linear correlation with preoptic anterior hypothalamic temperature. Plasma epinephrine values correlated with preoptic anterior hypothalamic temperature for only the controls at 28 degrees C ambient, whereas norepinephrine had significant linear correlation with heat production for all groups and significant negative linear correlation with preoptic anterior hypothalamic temperature. These data indicate norepinephrine may be more important than epinephrine in the maintenance of postburn hypermetabolism in this rat burn model while demonstrating that the hypermetabolism is appropriately responsive to perturbation of preoptic anterior hypothalamic temperature.
Caldwell
F T
FT
University of Arkansas for Medical Sciences, Department of Surgery, Little Rock 72205-7199.
Graves
D B
DB
Wallace
B H
BH
D000818:Animals; D001831:Body Temperature / Q000502:physiology; D001833:Body Temperature Regulation / Q000502:physiology*; D002056:Burns / Q000378:metabolism / Q000503:physiopathology*; D002151:Calorimetry; D002153:Calorimetry, Indirect; D004837:Epinephrine / Q000097:blood*; D016014:Linear Models; D008297:Male; D009638:Norepinephrine / Q000097:blood*; D011301:Preoptic Area / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley
D009638:Norepinephrine; D004837:Epinephrine