REVERSAL OF RESPIRATORY RESPONSES TO DOPAMINE AFTER DOPAMINE ANTAGONISTS
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Date
1982
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Abstract
The effects of dopamine (DA) antagonists on resting ventilation and ventilatory reactions to DA, apomorphine, hyperoxia and hypoxia were studied in pentobarbitone-anesthetized cats. Administration (i.v.) of spiroperidol, haloperidol, perphenazine and chlorpromazine increased resting ventilation, the intensity and duration of the effect being dependent on the dose of the blocker. The enhanced ventilation was associated to increased frequency of chemosensory discharges recorded from 1 carotid nerve and it was absent after section of the 4 buffer nerves. The drugs provoked a dose-dependent block of the transient chemosensory inhibitions and ventilatory depressions induced by DA or apomorphine. Spiroperidol and perphenazine reversed the inhibitory reactions to DA into excitatory ones, the ventilatory responses being abolished by section of carotid and aortic nerves. The ventilatory depressions caused by a few breaths of 100% O2 and the ventilatory excitations onset by a few breaths of 100% N2 persisted after applying DA blockers. DA antagonists apparently enhance ventilation by increasing peripheral chemosensory drive and may invert DA-induced reflex withdrawal into transient ventilatory excitation, without reversing the reflex ventilatory depression provoked by hyperoxia.