Reduction of hypoxic ventilatory drive by dopamine.

To define precisely the effects of dopamine on hypoxic ventilatory drive, two sets of experiments were performed in five healthy subjects. End-tidal CO2 was held constant in all experiments. First, a dopamine infusion (3 microgram/kg/min) was started in subjects already rendered hypoxic, causing an average sustained decrease in ventilation to 60% of the preinfusion ventilation. In the second group of experiments, the ventilatory response of subjects made hypoxic during a dopamine infusion was compared with the hypoxic ventilatory response without the dopamine infusion. Without dopamine, a sudden decrease in end-tidal O2 from 100 to 53 torr caused ventilation to increase from 11.9 to 20.9 L/min (p less than 0.01). During the dopamine infusion, only a statistically insignificant increase in ventilation (9.8 to 12.8 L/min) was seen with the same hypoxic stimulus. Low dose dopamine is a potent depressant of hypoxic ventilatory response.