Lack of direct interaction of metamyzole with the brain opiate receptors of rats
Popova, Y.; Staneva-Stoycheva, D.
Acta Physiologica et Pharmacologica Bulgarica 15(3): 55-58
1989
ISSN/ISBN: 0323-9950 PMID: 2557724 Document Number: 343526
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 effect of metamyzole are due to direct interaction with presynaptic opiate receptors. The method of radioligand binding of /3H/-nalaxone 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.