Chromatographic characterization of immunoreactive endothelin in rat lung

Using a specific and sensitive radioimmunoassay for endothelin, combined with gel filtration and reverse phase high performance liquid chromatography, the molecular form of immunoreactive endothelin in the rat lung was investigated. On reverse phase high performance chromatography, the major immunoreactive endothelin in the rat lung emerged at a position identical to that of authentic endothelin-1. After oxidation of the immunoreactive endothelin by H2O2, the immunoreactivity migrated to a position identical to that of Met-sulfoxide endothelin-1. These data indicate that the major immunoreactive endothelin in the rat lung is not endothelin-3 (putative rat/human endothelin), but is identical or very similar to endothelin-1 (porcine/human endothelin).