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KMID : 0900919940180020095
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Korean journal of Animal Reproduction
1994 Volume.18 No. 2 p.95 ~ p.99
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The Effect of a Potent Oxytocin Antagonist, Antag I, on In Vitro Uterine Contractions in Response to Exogenous Oxytocin and on Uterine Oxytocin Receptor Number and Affinity
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C, Warnell
G, Flouret
L. Wilson.Jr
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Abstract
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The purpose of the present study was to determine the in vivo effect of oxytocin antagonist-I(Al) on uterine oxytocin receptor number (Rn) and/or binding affinity (Kd) in the estrous rat. Anesthetized rats were given a bolus infusion of control or 5{mu}textrm{g} of AI and sacri-ficed 0.5 and 4 hours later. The uterine tissue was removed, trimmed and frozen. Membrane oxytocin receptors were isolated after homogenization of uterine tissue and differential ultracentrifugation. The oxytocin receptor assay was performed by saturation with cold oxytocin competion with a high specific activity oxytocin antagonist. Rn and Kds were determined by nonlinear curve fitting methods. No differences(p>0.05) between the AI and control treated animals in either oxytocin receptor number or binding affinity was detected in this study. These data suggest that the major mode of action of AI is via competitive inhibition at the uterine oxytocin receptor and not by altering receptor number or binding affinity.
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