Alpha 2-adrenoceptors in the guinea-pig uterus: heterogeneity in the circular and longitudinal smooth muscle layers.
Eur J Pharmacol
; 250(2): 231-7, 1993 Dec 07.
Article
em En
| MEDLINE
| ID: mdl-7906651
ABSTRACT
Homogenate binding and functional studies have been undertaken to investigate the role of alpha 2-adrenoceptors on the circular and longitudinal myometrial layers of the dioestrous guinea-pig uterus. Each myometrial layer contained a single population of [3H]rauwolscine binding sites (KD values approximately 3 nM) for which yohimbine exhibited a higher affinity than prazosin, and xylazine a higher affinity than phenylephrine, indicating the presence of alpha 2-adrenoceptor binding sites. In circular myometrium, xylazine enhanced contractile responses, was more potent than either noradrenaline or phenylephrine in inhibiting forskolin-stimulated accumulation of cyclic AMP, and reduced the inhibitory effect of forskolin on phenylephrine-induced phosphatidyl inositol hydrolysis. In longitudinal myometrium xylazine enhanced contractile responses to phenylephrine but did not inhibit forskolin-stimulated accumulation of cyclic AMP. We conclude that alpha 2-adrenoceptor binding sites are present in both uterine layers and mediate uterine contractility possibly through different mechanisms.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Útero
/
Receptores Adrenérgicos alfa 2
/
Músculo Liso
Limite:
Animals
Idioma:
En
Revista:
Eur J Pharmacol
Ano de publicação:
1993
Tipo de documento:
Article
País de afiliação:
Austrália