title: Lack of direct interaction of metamyzole with the brain opiate receptors of rats.
abstract: In earlier studies (Ivanov, Staneva-Stoycheva, 1984) we have found an inhibitory effect of metamyzole (Analgin-Pharmachim) on the contractile responses of electrically stimulated guinea-pig ileum and mouse vas deferens, which is antagonized by naloxone. In the present study an attempt is made to clarify whether these presynaptic effects of metamyzole are due to direct interaction with presynaptic opiate receptors. The method of radioligand binding of /3H/-naloxone to the opiate receptors in a crude membrane fraction of rat brain was used. It was found that in the wide concentration range used (10(-5)-10(-9) M), metamyzole does not compete with /3H/-naloxone for binding to the receptor sites. The biochemical study has shown that the presynaptic opiate receptors do not participate in the mechanism of the presynaptic effects of metamyzole, established in earlier studies.
authors.affiliation: Institute of Physiology, Bulgarian Academy of Sciences.
authors.forename: Y
authors.initials: Y
authors.lastname: Popova
authors.forename: D
authors.initials: D
authors.lastname: Staneva-Stoycheva
mesh_terms: D000632:Aminopyrine / Q000031:analogs & derivatives*; D000818:Animals; D001923:Brain Chemistry / Q000187:drug effects*; D004177:Dipyrone / Q000494:pharmacology*; D007700:Kinetics; D008297:Male; D009270:Naloxone / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011957:Receptors, Opioid / Q000187:drug effects*
chemical_list: D011957:Receptors, Opioid; D000632:Aminopyrine; D009270:Naloxone; D004177:Dipyrone