MRC Blood Pressure Unit, Western Infirmary, Glasgow, Gil 6NT
(Received 19 December 1977)
Only a few of the radioimmunoassays for vasopressin (AVP) published previously (Dunn, Brennan, Nelson & Robertson, 1973; Möhring & Möhring, 1975) have been sensitive enough for use in the rat. This communication describes a novel method for extraction of AVP from plasma involving the use of a solid-phase antibody and its application in a radioimmunoassay sufficiently sensitive to detect this hormone in rat plasma.
Antiserum to AVP (102/5, 250 μl; Morton, Padfield & Forsling, 1975) was coupled to CNBr-Sepharose 4B (2 g) by mixing for 18 h at room temperature in 0·1 m-NaHC03-0·5 m-NaCl (15–20 ml). The solid antiserum was mixed with 0·2 m-Tris-HCl, pH 8·0, for 18 h and then washed with 1 m-acetic acid (200 ml). The solid antibody was finally equilibrated with 42·5 ml 0-05 m-Tris-HCl, pH 7·5, to give an antiserum dilution of