Naloxone-induced contracture of ileum from stressed guinea pigs.
The in vitro preparation of guinea-pig ileum taken from animals which had been stressed by swimming for 5 min in water at 20 degrees C responded by a dose-dependent contracture to the narcotic antagonist naloxone. This response was antagonised by atropine (8 X 10(-8) g/ml). Ileum preparation from non-stressed guinea pigs did not respond to naloxone in concentrations up to 1 X 10(-5) g/ml. The possibility that this response is a consequence of the stress-induced release of endogenous opiate peptides is discussed.
D000109:Acetylcholine / Q000378:metabolism; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D006168:Guinea Pigs; D006632:Histamine / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects*; D009270:Naloxone / Q000494:pharmacology*; D013315:Stress, Psychological / Q000503:physiopathology*; D013550:Swimming
D009270:Naloxone; D001285:Atropine; D006632:Histamine; D000109:Acetylcholine