EFFECTS OF DOPAMINE AND DOMPERIDONE ON VENTILATION DURING ISOCAPNIC HYPOXIA IN HUMANS

In order to investigate the role of dopamine in the ventilatory response to sustained, isocapnic hypoxia six subjects were studied three times in each of three pharmacological conditions: (1) in the absence of any drug administration, (2) during i.v. infusion of dopamine (3-mu-g.kg-1.min-1), and (3) after pretreatment with domperidone. Otherwise the experimental protocol was identical on each day and consisted of holding the subjects' end-tidal P(O2) at 100 Torr for 10 min, then 50 Torr for 20 min and finally at 100 Torr again for 5 min. End-tidal P(CO2) was held constant 2-3 Torr above normal throughout the experiment. Domperidone increased, and dopamine decreased the magnitudes of both the fast on- and off-responses, but neither drug affected the magnitude of the hypoxic ventilatory decline (HVD). The results of this study suggest: (1) that a peripheral dopaminergic mechanism is not involved in the genesis of HVD, and (2) the peripheral chemoreflex may be modulated peripherally to produce HVD.