Failure of narcotic antagonist to alter electroacupuncture modification of halothane anaesthesia in the dog.

Sixteen dogs were used to study the analgesic effects of electroacupuncture. Electroacupuncture lowered halothane MAC significantly (1.21 +/- 0.04 to 1.05 +/- 0.05 per cent, p less than 0.005). Reversibility of this effect by narcotic antagonist was then studied, using naltrexone 5 mg . kg-1 injected intravenously (10 dogs) or 0.5 mg . kg-1 intrathecally (3 dogs). We failed to see any reversal of the effect of electroacupuncture on MAC. Narcotic antagonist reversibility of acupuncture effect is taken currently to imply endorphin mediation. Possible explanation for our result include an electroacupuncture analgesia not mediated by endorphins.