Naloxone fails to antagonize the righting response in rats anesthetized with halothane.

The righting responses of 75 Wistar rats during exposure to halothane, 0.5 per cent, 10 min after subcutaneous injection of naloxone, 10 or 20 mg/kg, or saline solution were examined. There was no difference in recoveries of the righting responses among the three groups. It is concluded that naloxone does not antagonize the loss of righting response produced by halothane anesthesia in the rat.