Evidence of non-synaptic regulation of postpartum uterine contractility in the rat

LIFE SCIENCES

卷:62

Article

Gaspar, R ; Marki, A ; Zupko, I ; Falkay, G

关键词: myometrium;    electric field stimulation;    receptor density;    non-synaptic regulation;   

DOI  :  10.1016/S0024-3205(98)00035-6

来源: Elsevier

【 摘 要 】

Myometrial tissue rings from postpartum rats (24 h after delivery) were studied in vitro by electric field stimulation, and the alpha(1)/beta(2)-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 beta(2)-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 beta(2)-agonists. Receptor assays revealed that the alpha(1)/beta(2) ratio was about 2 in the measured uteri. It was concluded that the inhibitory effects of alpha-antagonists and beta(2)-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 alpha(1)-adrenoceptors in smooth muscle.

【 授权许可】

Free