Rat myometrial adrenergic receptors in late pregnancy.
The myometrium of the rat has been found to contain both alpha 1- and beta-adrenergic receptors. To investigate the implication of these adrenergic receptors in uterine reactivity near term delivery, we have measured the number and the affinity of alpha 1-adrenergic antagonist [( 3H]prazosin: [3H]PRAZ)-binding sites and of very high affinity beta 2-adrenergic agonist [( 3H]hydroxybenzylisoproterenol: [3H]HBI)-binding sites in myometrial membranes throughout the last 5 days of pregnancy and at delivery. The number of specific binding sites was constant from Day 18 of pregnancy up to 6 h prior to birth. In the last 6 h of pregnancy, there was a sharp increase in the number of alpha 1-receptors (+70%, p less than 0.05). Simultaneously, the number of beta 2-receptors coupled to the adenylate cyclase system dropped (-75%; p less than 0.001). These results indicate that with the approach of parturition, there is a regulation of uterine reactivity by a modulation of the concentrations of myometrial adrenergic receptors during the last 6 h of gestation.
Legrand
C
C
Laboratoire de Physiologie de la Reproduction, Université Pierre et Marie Curie, Paris, France.
Maltier
J P
JP
Benghan-Eyene
Y
Y
D015720:5'-Nucleotidase; D000818:Animals; D005260:Female; D007545:Isoproterenol / Q000031:analogs & derivatives / Q000378:metabolism; D009215:Myometrium / Q000378:metabolism*; D009708:Nucleotidases / Q000378:metabolism; D011224:Prazosin / Q000378:metabolism; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000378:metabolism*; D011869:Radioligand Assay; D051381:Rats; D011919:Rats, Inbred Strains; D011942:Receptors, Adrenergic, alpha / Q000378:metabolism*; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*
D011942:Receptors, Adrenergic, alpha; D011943:Receptors, Adrenergic, beta; C015272:hydroxybenzylisoproterenol; D009708:Nucleotidases; D015720:5'-Nucleotidase; D007545:Isoproterenol; D011224:Prazosin