Naloxone does not affect ventilatory responses to hypoxia and hypercapnia in rats

Ventilatory responses (tidal volume, respiratory frequency, and minute ventilation) to steady-state hypoxia and steady-state hypercapnia were measured plethysmographically in awake unrestrained adult rats, before and after subcutaneous injection of placebo (saline) naloxone in doses up to 5.0 mg/kg. Naloxone did not alter the ventilatory responses to hypoxia or hypercapnia.