Development of a Solid-Phase Radioimmunoassay for the Determination of Arginine-Vasopressin in Urine

Abstract

A new solid-phase radioimmunoassay (RIA) has been developed for measuring arginine-vasopressin (AVP) in urine. AVP is first extracted from urine by adsorption on Vycor glass powder and eluted with acetone-water (60:40). The mean recovery is 75.3 ± 2.2% (n =18). The organic extract is evaporated to dryness and reconstituted in the assay buffer. Aliquots of this extract are then incubated with ¹²⁵I-AVP in polystyrene LKB tubes previously coated with the antiserum (1:50000) for 48 hours. The free radioactive fraction is removed by aspiration and the tubes are counted. Values correlate well with those obtained by liquid-phase RIA using dextran-charcoal. Urinary AVP concentrations in normal Sprague-Dawley rats and rats with varying degrees of hydration have been measured.

Key Words:

• arginine-vasopressin
• solid-phase radioimmunoassays
• hormone assays
• neuropeptides
• peptide hormones
• urine extracts