[Effect of dopamine receptor on hypoxic ventilatory response].

We studied the effect of intravenous administration of a dopamine (DA) agonist and antagonist on the hypoxic response of phrenic nerve activity in anesthetized, vagotomized and mechanically ventilated rabbits. The experiments were performed in both intact and carotid sinus denervated animals. In the intact animals, hypoxic challenge (FIO2 = 0.10) increased the amplitude of integrated phrenic nerve activity (iPNA) without any alteration in respiratory frequency. In the carotid sinus denervated animals, the hypoxia progressively depressed iPNA. Neither the DA antagonist, haloperidol (0.5mg/kg i.v.), nor the DA agonist, apomorphine (0.3mg/kg, i.v.) changed the iPNA during normoxia in either the intact or denervated group. Administration of haloperidol enhanced iPNA response to hypoxia in the intact group. Apomorphine decreased the hypoxic response to iPNA. Although apomorphine did not change the control hypoxic response to iPNA in the denervated group, haloperidol augmented hypoxic respiratory depression in the carotid sinus denervated group. Therefore, we concluded that the effect of DA on peripheral chemoreceptors inhibits the hypoxic ventilatory response, but stimulates the hypoxic ventilatory response in the central nervous system.