Selective distribution of alpha-1 and beta adrenoceptors in pregnant rat uterus visualized by autoradiography.
Receptor autoradiography using (-)-3-[125I]cyanopindolol and [3H]prazosin was used to study the distribution of beta and alpha-1 adrenoceptors in the rat uterus at early and midpregnancy. The binding of [3H]prazosin to slide-mounted sections at 25 degrees C was time dependent (K1 = 3.01 x 10(7) M-1 min-1, K2 = -0.0116 min-1) and saturable (1 nM). Competition binding curves with the selective alpha-1 and alpha-2 antagonists (prazosin, yohimbine) or alpha-1 and alpha-2 agonists (phenylephrine, clonidine) showed the presence of alpha-1 adrenoceptors; autoradiographic studies revealed that this subtype is highly localized in the circular layer of the myometrium during pregnancy. (-)-3-[125I]Cyanopindolol binding to slide-mounted sections of the pregnant uterus at 25 degrees C was time dependent (K1 = 4.68 x 10(8) M-1 min-1, K2 = -0.0117 min-1) and saturable (200 pM). Competition binding curves with beta-1 or beta-2 selective agonists (dobutamine, metaproterenol) and antagonists (atenolol, ICI 118,551) revealed the presence of beta adrenoceptors in the proportion of 67% beta-2 to 33% beta-1. Hyperfilm exposed to sections of the whole pregnant uterus incubated with (-)-3-[125I]cyanopindolol with or without ICI 118,551 or atenolol showed a high density of beta-2 adrenoceptors in the longitudinal layer of the myometrium and in the placenta. A small density of beta-2 adrenoceptors was also located in the decidua basalis on day 8 of pregnancy.
Legrand
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C
Laboratoire de Physiologie de la Reproduction, CNRS URA 555, Université Pierre et Marie Curie, Paris, France.
Vivat
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Rigolot
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Maltier
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JP
D000818:Animals; D001345:Autoradiography; D005260:Female; D020120:Iodocyanopindolol; D010869:Pindolol / Q000031:analogs & derivatives / Q000378:metabolism; D011224:Prazosin / Q000378:metabolism; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D011942:Receptors, Adrenergic, alpha / Q000032:analysis*; D011943:Receptors, Adrenergic, beta / Q000032:analysis*; D014599:Uterus / Q000737:chemistry*
D011942:Receptors, Adrenergic, alpha; D011943:Receptors, Adrenergic, beta; D020120:Iodocyanopindolol; D010869:Pindolol; D011224:Prazosin