Isolation of human intestinal neurotensin.

The biologically active peptide neurotensin (NT) has been isolated from fresh postmortem human small intestine and its identity with bovine hypothalamic and intestinal neurotensin has been established. Purification was achieved by gel filtration and two ion exchange chromatography steps; material was detected by radioimmunoassay (RIA). A substance was obtained that had integral molar ratios of amino acids and eluted in a single peak during reverse-phase high pressure liquid chromatography (HPLC). This material had an amino acid composition and COOH-terminal sequence identical with those of bovine NT. Human and bovine neurotensin gave rise to the same fragments when treated with papain; they were indistinguishable in RIAs using three different region-specific antisera and in their hypotensive effect on anesthetized rats. Using mucosal scrapings obtained immediately post-mortem from four subjects, the concentration of immunoreactive neurotensin was found to increase from duodenum to distal ileum, in agreement with results obtained in other mammalian species.