Radioimmunoassay of vasopressin in unextracted plasma.

A radioimmunoassay (RIA) for arg8-vasopressin (AVP) in unextracted human plasma was based on a sensitive anti-AVP rabbit antiserum, inhibition of enzymatic damage to [125I]AVP and AVP, and the use of an individual plasma blank, to correct for interference of plasma factors with the RIA. Sensitivity was 0.4 pg of synthetic AVP detected, corresponding to 1.

The effect of indomethacin on kidney function and plasma renin activity in man.

125Iothalamate and 131I-hippuran clearances, sodium excretion and plasma renin activity (PRA) before and during indomethacin administration in an oral dose of 3 x 50 mg/day were studied in volunteers with a normal or reduced kidney function, as well on non-sodium-restricted as on sodium-restricted diet. Indomethacin induced a temporary sodium and water retention and a decrease in glomerular filtration rate. It also lowered PRA.

Scatchard plot and heterogeneity in binding affinity of labeled and unlabeled ligand.

In saturation analysis the Scatchard plot is a generally accepted method for calculation of the affinity constant, K, and the molar concentration, q, of the binder. However, in a system where the K's for the labeled and unlabeled ligand are unequal, a nonlinear plot can be obtained from which incorrect values for K and q may be calculated. This paper mathematically explains how the plot may deviate and under which conditions there will be a maximum in the curve.