Studies on the method of measurement of urinary antidiuretic hormone, 2

The results of basic studies on the radioimmunoassay are summarized as follows: The favorable conditions for preparing 131I-vasopressin. The optimal amount of chloramine T. Under the conditions using 1 to 1.5 mCi of 131I, 10 or 1 μg of lysine vasopressin (LVP) at pH 7.5, the greatest peak values were seen on utilizing of 16 - 20 μg chloramine T. The effect of chloramine T was greater at pH 7.5 than at pH 6.0. The peak value increased up to 85 μCi by decrease of the liquid volume from 0.165 - 0.18 ml to 0.11 ml at the marking process. In addition, the peak values further increased up to 106 - 110 μCi by adding LVP to the mixture sample of 131I and chloramine T. The adsorption ratios of 131I-LVP into activated charcoal-dextran T70 mixture were estimated at about 98 - 99%. In these examinations the concentration of activated charcoal was between 15 - 2.5%, and that of dextran T70 was between 1 - 0.25%. Concerning the binding ratios of 131I-LVP to bovine serum albumin, bovine thyroglobulin and pig γ-globulin, the remaining radioactivities were examined. It was estimated that about a half of added 131I-LVP was bound to each protein. A suspension of LVP-bovine serum albumin complex and complete Freunds adjuvant was injected (1 mg per injection) subcutaneously or intramuscularly to 3 rabbits within the interval of 3 weeks, and after 23 weeks the blood sampling was collected. As a result, the antibody production was observed in one rabbit on the standard curve with this antibody it was possible to measure the concentrations between 5 and 10 μU of arginine vasopressin. (auth.)