LOCALIZATION OF BRADYKININ B-2 RECEPTORS IN SHEEP UTERUS

The localization and characterization of bradykinin B-2 receptors in s heep uterus was carried out using a radiolabelled B-2 receptor ligand, Arg(0)-[Hyp(3),Thi(5),D-Tic(7),D-OiC(8)]bradykinin (HPP-HOE140). Comp etition of the radioligand, [I-125]HPP-HOE140, from membrane preparati ons of anoestrus sheep uterus by bradykinin agonists and antagonists r evealed the presence of high- and low-affinity binding sites with liga nd specificity typical of the bradykinin B-2 receptor. Using in vitro autoradiography on tissue sections, intense binding was visible over t he superficial epithelial layer of the endometrium and inner third of the myometrium of anoestrus sheep uterus. Bradykinin Bz receptors in t he myometrium were down regulated in pregnant sheep uterus. We demonst rate that binding studies using [I-125]HPP-HOE140 offer high sensitivi ty and specificity for characterization, quantitation and localization of the bradykinin B-2 receptors in tissues and offers new information on uterine bradykinin B-2 receptors.