Characterization of endometrial and myometrial oxytocin receptors in the non-pregnant ewe.
Oxytocin-binding sites in the endometrium and myometrium of the non-pregnant ewe were characterized. [3H]Oxytocin bound to a single site in both tissues with high affinity; dissociation constants were determined to be 1.96 nmol/l in endometrium and 2.12 nmol/l in myometrium. Oxytocin binding was enhanced by divalent cations with a similar order of potency in both tissues: Co2+ greater than Mn2+ greater than Ni2+ greater than Mg2+ greater than Zn2+ greater than Ca2+. The endometrial and myometrial binding sites showed the same specificity for oxytocin analogues and related peptides, having high affinity for oxytocin, [Arg8]-vasopressin, [Lys8]-vasopressin, and the oxytocin-specific agonists [Gly7]-oxytocin and [Thr4,Gly7]-oxytocin. The results suggest that oxytocin receptors present in the endometrium and myometrium of the ewe are similar both to each other and to classical oxytocin receptors.
Ayad
V J
VJ
Department of Anatomy, Medical School, University of Bristol.
Wathes
D C
DC
D000818:Animals; D001665:Binding Sites; D001667:Binding, Competitive; D002412:Cations; D004717:Endometrium / Q000378:metabolism*; D005260:Female; D006358:Hot Temperature; D009215:Myometrium / Q000378:metabolism*; D010121:Oxytocin / Q000378:metabolism*; D011945:Receptors, Angiotensin / Q000378:metabolism*; D018045:Receptors, Oxytocin; D012756:Sheep; D013997:Time Factors
D002412:Cations; D011945:Receptors, Angiotensin; D018045:Receptors, Oxytocin; D010121:Oxytocin