NALOXONE STIMULATES OXYGEN-CONSUMPTION BUT NOT VENTILATION IN HYPOTHYROID HAMSTERS

Male golden Syrian hamsters made hypothyroid by 5 wk of propylthiourac il (PTU) treatment and control hamsters given tap water were studied. Both groups of nine animals demonstrated increased oxygen consumption after SC naloxone administration relative to saline treatment Naloxone stimulated ventilation and ventilation in response to hypoxic (10% O- 2) and hyperoxic, hypercapnic (7% CO2 in oxygen) challenges in control hamsters. Relative to their responses to saline, PTU-treated hamsters exhibited no stimulation of ventilation nor of ventilation in respons e to the gas challenges after naloxone treatment. These results sugges t that (a) the stimulation of oxygen consumption by naloxone does not directly increase ventilation; and (b) thyroid hormone status in the h amster affects opioid modulation of ventilation.