Antagonism of opiate mydriasis in mice.
1 Morphine-induced mydriasis in mice is antagonized by nalorphine, levallorphan and naloxone in a dose-dependent manner. 2 The relative potency of the three agents is 10:56: 134 respectively, thus being in accordance with other tests of narcotic antagonism. Naloxone has the shortest duration of action. 3 When injected into naive animals, nalorphine (but not levallorphan or naloxone) produces a slight mydriasis. 4 Measurement of the diameter of the pupil in mice seems to be a precise, simple and rapid test for studying narcotic antagonist as well as agonist action and has several advantages over standard methods used for this purpose.
D000818:Animals; D004305:Dose-Response Relationship, Drug; D007977:Levallorphan / Q000494:pharmacology*; D008297:Male; D051379:Mice; D009020:Morphine / Q000037:antagonists & inhibitors*; D009184:Mydriatics / Q000037:antagonists & inhibitors*; D009269:Nalorphine / Q000494:pharmacology*; D009270:Naloxone / Q000494:pharmacology*; D011680:Pupil / Q000187:drug effects*
D009184:Mydriatics; D007977:Levallorphan; D009270:Naloxone; D009020:Morphine; D009269:Nalorphine