INFLUENCE OF CAROTID DENERVATION ON THE BODY-CORE TEMPERATURE AND METABOLIC RESPONSES TO CHANGES IN AMBIENT-TEMPERATURE DURING NORMOXEMIA AND ACUTE HYPOXEMIA IN GUINEA-PIGS DURING POSTNATAL MATURATION

Acute hypoxemia produces a decrease in body-core temperature T-bc in g uinea pigs during postnatal maturation, although the factors mediating the response remain unknown. Experiments were therefore carried out t o test the hypothesis that the carotid chemoreceptors and (or) barorec eptors mediate the decrease in T-bc during acute hypoxemia. Twelve gui nea pigs, six carotid intact and six carotid denervated, were studied in a metabolic chamber to determine the influence of carotid denervati on on the T-bc and metabolic (i.e., oxygen consumption) responses to c hanges in ambient temperature during normoxemia and during acute hypox emia at 2, 3, and 4 weeks of age. Carotid denervation accentuated the decrease in T-bc in response to a decrease in ambient temperature duri ng normoxemia at 2 and 3 weeks of age but not at 4 weeks of age withou t altering the metabolic response. This suggests that carotid denervat ion disrupted heat conservation mechanisms rather than heat production mechanisms in an age-specific manner. Furthermore, carotid denervatio n accentuated the decrease in Tbe and oxygen consumption in response t o acute hypoxemia at all ages studied. This provides evidence that the carotid chemoreceptors and (or) baroreceptors do not mediate the decr ease in T-bc that occurs in response to acute hypoxemia in guinea pigs during postnatal maturation.