Distribution of neurotensin-like immunoreactivities in porcine and human gut.

The distribution of neurotensin-like immunoreactivity (NTLI) in porcine and human intestine was studied by extraction of mucosal and muscular layers of esophagus, stomach, duodenum, jejunum, ileum, and colon. NTLI was quantitated and characterized by radioimmunoassays and gel filtration chromatography. Porcine tissue was obtained in anesthetized animals (n = 6) and human tissue during surgery (n = 28). Concentrations of NTLI increased gradually from the distal esophagus to the ileum. Highest concentrations were found in 2.0 M acetic acid extracts of proximal ileal mucosa (150 (131-223) and 525 (500-729) pmol/g wet tissue, respectively (medians and interquartile range]. After acid extraction, concentrations of intact NT and COOH-terminal and NH2-terminal NTLI were similar, but in water concentrations of NH2-terminal NTLI were high and intact NT and COOH-terminal NTLI low. The distribution of NTLI was similar in the two species. Gel chromatography of ileal, jejunal, and duodenal mucosa indicated that in these tissues NTLI consisted primarily of intact NT. In antral mucosa COOH-terminal immunoreactivity different from NT was detected. The chemical identity is unknown, but it may represent precursor forms of NT.