The characterization of growth hormone release inhibiting hormone-like immunoreactivity in normal urine

Using a previously described radioimmunoassay for growth hormone release inhibiting hormone (GH-RIH), the presence of GH-RIH-like immunoreactivity in urine has been characterized by demonstrating mobility identical to synthetic GH-RIH standard on two sephadex gel chromatographic systems, and parallelism of dilutions of the sephadex fractions with synthetic GH-RIH. Furthermore, 74% of the sephadex fraction cross-reacting in the immunoassay bound to antibody conjugated to sepharose and could be eluted by 1 M acetic acid. This immunospecific eluate showed identity with synthetic GH-RIH on both ion exchange and thin layer chromatography. Thus GH-RIH-like immunoreactivity is present in normal urine; this may have potential relevance in the search for a physiological role for this peptide.