Evidence of non-synaptic regulation of postpartum uterine contractility in the rat.
Life Sci
; 62(12): 1119-24, 1998.
Article
em En
| MEDLINE
| ID: mdl-9519814
ABSTRACT
Myometrial tissue rings from postpartum rats (24 h after delivery) were studied in vitro by electric field stimulation, and the alpha1/beta2-adrenoceptor ratio was determined by a radioligand binding technique. Pregnancy-denervated uterine rings were stimulated by long-duration pulses (100 ms). The contractions were inhibited by beta2-agonists (terbutaline and fenoterol) and alpha-antagonists (phentolamine, urapidil and yohimbine) in a concentration-dependent manner. Their effects were not altered by the adrenergic neuron-blocking agent bretylium. The alpha-antagonists (except phentolamine) elicited the same maximal inhibition as the beta2-agonists. Receptor assays revealed that the alpha1/beta2 ratio was about 2 in the measured uteri. It was concluded that the inhibitory effects of alpha-antagonists and beta2-agonists are mediated via non-synaptic adrenoceptors of the denervated postpartum rat uterus. The same inhibitory activity could be explained by the greater amount of alpha-receptors. It is believed that this is the first functional proof of the existence of non-synaptic alpha1-adrenoceptors in smooth muscle.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Sinapses
/
Contração Uterina
/
Útero
/
Receptores Adrenérgicos alfa
/
Receptores Adrenérgicos beta
/
Período Pós-Parto
Limite:
Animals
Idioma:
En
Ano de publicação:
1998
Tipo de documento:
Article