Autonomic and behavioral thermoregulation in guinea pigs during postnatal maturation

Fewell, James E., Maria Kang, and Heather L. Eliason.Autonomic and behavioral thermoregulation in guinea pigs during postnatal maturation. J. Appl.Physiol. 83(3): 830-836, 1997.Serial experimentswere carried out on seven chronically instrumented Hartley-strainguinea pigs at 1, 3, and 5 wk of age to define their autonomic andbehavioral thermoregulatory profiles and to test the hypothesis thatthey have the mechanisms in place shortly after birth that allow themto optimize their energy expenditure for thermoregulation by selectinga thermal environment that requires the lowest metabolic oxygenrequirements. Each animal was studied in both a thermocline todetermine selected ambient temperature and in a metabolic chamberto determine the thermoregulatory response to forced changes in ambienttemperature. In the thermocline, the guinea pigs at all postnatal agesselected an ambient temperature that placed core temperature, oxygenconsumption, thermal conductance, heart rate, and respiratory rate atlevels comparable to those observed at ambient temperatures in whichminimal oxygen consumption occurred in the metabolic chamber. Thus ourexperiments provide evidence that guinea pigs have theneurophysiological mechanisms in place shortly after birth that allowthem to optimize their energy expenditure for thermoregulation byselecting a thermal environment that corresponds to the lowestmetabolic oxygen requirements.