Iodination and binding characteristics of 125I-d(CH2)5 [Tyr(Me)2, Tyr(NH2)9] AVP

Abstract

With iodinated vasopressin analogue, d(CH2)5[Tyr(Me)2, Tyr(NH2)9] AVP, at position 9, followed by purification by HPLC (specific activity 473-543Ci/mmol), a specific binding was observed in the rat liver plasma membrane fraction. Scatchard analysis indicated a single class of high-affinity binding sites with a Kd of 0.23nM and Bmax of 142fmol/mg protein. V2-agonist, DDAVP, did not displace 125I-vasopressin analogue. These results suggest that 125I-d(CH2)5[Tyr(Me)2, Tyr(NH2)9] AVP with a high specific activity is a useful tool to investigate V1-receptors.