Depression of hypoxic ventilatory response in humans by somatostatin.

In nine normal subjects we measured the ventilatory response to isocapnic hypoxia with and without an intravenous infusion of 1 mg of somatostatin. Arterial O2 saturation was rapidly lowered to 80 +/- 2% in 2 min and maintained for 30 min. During control experiments, ventilation increased immediately (3-5 min) and then declined so that at 25 min of hypoxia ventilation was little above that in room air. Somatostatin was associated with a small decrease in ventilation while the subjects breathed room air. With hypoxia there was no immediate increase in ventilation for the group as a whole, although an increase was observed in one subject. With somatostatin, after 25 min of hypoxia, mean ventilation was lower than at any other time in the study; as hypoxia was discontinued ventilation increased slightly. Somatostatin causes profound depression of the ventilatory response to hypoxia by a mechanism that is not known but may be central. With somatostatin hypoxia of 25-min duration tends to depress ventilation.