CAROTID-BODY DOPAMINERGIC MECHANISMS ARE FUNCTIONAL AFTER ACCLIMATIZATION TO HYPOXIA IN GOATS

Ventilatory acclimatization to sustained hypoxia (VASH) is the time-de pendent increase in Ventilation that occurs during prolonged exposure to hypoxia. We tested the hypothesis that carotid body (CB) dopaminerg ic mechanisms are down-regulated during VASH, which would allow CB aff erent discharge and ventilation to increase beyond the initial respons e to hypoxia. Domperidone (DOM; 1.0 mg.kg(-1)) was administered intrav enously to block CB dopamine (DA) receptors after VASH was complete in awake goats. DOM caused a significant augmentation of the ventilatory response to hypoxia in acclimatized goats, failing to support the hyp othesis. We conclude that inhibitory CB dopaminergic function is not s ignificantly reduced following prolonged hypoxia, and that down-regula tion of CB dopaminergic mechanisms may not be involved in VASH in the goat. (C) 1998 Elsevier Science B.V.