Intracarotid dopamine infusion does not prevent acclimatization to hypoxia.

Ventilatory acclimatization to hypoxia (VAH) is the time-dependent increase in ventilation that occurs during sustained exposure to hypoxia. The mechanism for VAH remains elusive. We sought to determine whether a deficiency in the availability of carotid body dopamine is the mechanism of increased ventilatory responsiveness to hypoxia during VAH in awake goats. This was based on the evidence that dopamine (DA) is primarily an inhibitory neuromodulator of carotid body (CB) function. The hypothesis was tested by intracarotid infusion of DA (5.0 micrograms kg-1 min-1) throughout VAH. VAH was not prevented by DA infusion, failing to support the hypothesis. We conclude that a deficiency in the availability of inhibitory DA release within the CB is probably not responsible for VAH. However, increased ventilatory responses to acute hypoxia after either prolonged DA infusion or hypoxia may have similar CB mechanisms.