Determination of plasma ET-1 by RIA--risks and limitations.

ABSTRACT

Plasma concentrations of the vasoconstrictor peptide endothelin-1 (ET-1) were determined in nonobese healthy subjects as well as in unspecified patients using three different commercially available radioimmunoassays (RIAs) and the respective recommended prepurification procedures. Depending on the antibody and extraction procedure applied different ET-1 concentrations were measured in identical plasma samples. Thus, this study clearly documents that ET-1 concentrations measured in plasma samples represent apparent concentrations which have to be interpreted with caution.