Anesthesiology. 49(1):6–8, JULY 1978
PMID: 666051
Issn Print: 0003-3022
Publication Date: July 1978
Naloxone Has No Effect on Nitrous Oxide Anesthesia
Raymond Smith;Michael Wilson;Keith Miller;
+ Author Information
*Research Fellow, Harvard Medical School.†Research Assistant, Massachusetts General Hospital.‡ Associate Professor of Pharmacology in the Department of Anesthesia, Harvard Medical School.Received from the laboratories of the Department of Anesthesia, Harvard Medical School at the Massachusetts General Hospital, Boston, Massachusetts 02114. Accepted for publication January 6, 1978. Supported in part by an Office of Naval Research contract (N00014–75-C-0727) with funds provided by the Naval Medical Research and Development Command and in part by a grant from the National Institute of General Medical Sciences (GM-15904). Dr. Miller is supported by a Public Health Service Career Development Award (GM-00199) from the National Institute of General Medical Sciences.
Abstract
It has been reported that naloxone antagonizes general anesthesia in rats when the tail clamp is used as a painful stimulus to assess anesthesia.1 The authors' hypothesis is that this antagonism is to the analgesic component of anesthesia only, and that anesthesia assessed by a non-painful stimulus would not be antagonized by naloxone. Therefore, the anesthetic potency of nitrous oxide in mice was measured using loss of the righting reflex as a non-painful stimulus. Naloxone, 2 and 16 mg/kg, intrapcritoncally, failed to antagonize nitrous oxide anesthesia measured 14–39 min after injection. Thus, 19 min after injection of naloxone, 2 mg/kg, the nitrous oxide ED50 was 1.25 ± 0.060 atm (n = 35), compared with 1.19 ± 0.053 atm (n = 35) after injection of saline solution (control). Following naloxone, 16 mg/kg, the nitrous oxide ED50 was 1.18 ± 0.059 atm (n = 35), compared with 1.22 ± 0.059 atm (n = 35) for saline solution. At neither dose of naloxone was the ED50 different from the control ED50, a finding that supports the authors' hypothesis.
