A radioimmunoassay for neurotensin in human plasma

A specific radioimmunoassay for neurotensin in plasma has been developed with a sensitivity of 2 pmol/l of plasma. The antiserum was directed towards the amino terminal region of neurotensin and did not cross-react with other gastrointestinal peptides. Non-specific interference was eliminated and the sensitivity increased by extracting the plasma samples with ethanol prior to assay. Within- and between-assay coefficients of variation were 7.8% and .12% respectively. The mean plasma concentration of neurotensin in 30 fasting subjects was 29 +/- 4 pmol/l. A mixed meal increased plasma neurotensin from 16 +/- 2 to 53 +/- 6 pmol/l at 2 h.