Catabolism of neurotensin in interstitial fluid of the rat stomach.
The catabolism of neurotensin (NT) was studied in the gastric submucosa of the conscious rat using a novel technique to obtain a dialysate of interstitial fluid. A microdialysis fiber system was surgically implanted into the gastric submucosa, and 2 days later experiments were commenced on conscious animals. Isotope-labeled NT was administered to the tissue, and a dialysate of the submucosal interstitial fluid was collected. In the dialysate, NT and catabolites of NT formed in the interstitial fluid were identified and quantitated by high-pressure liquid chromatography. The catabolism of 125I-NT-(1-13) and [3H]NT-(1-13) was studied as was the further breakdown of the major catabolites. NT-(1-13) was, regardless of the type of label, catabolized mainly into NT-(1-8), NT-(9-13), NT-(1-11), and free tyrosine. None of the catabolites formed is known to possess significant biological activity. NT-(9-13) was rapidly cleared, whereas the amino-terminal fragments NT-(1-8) and NT-(1-11) were more resistant to degradation. The biological half-life of neurotensin in the gastric submucosa of the rat was between 9 and 15 min.
D000818:Animals; D001826:Body Fluids / Q000032:analysis / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D005753:Gastric Mucosa / Q000378:metabolism*; D007457:Iodine Radioisotopes; D007700:Kinetics; D008297:Male; D009496:Neurotensin / Q000032:analysis / Q000378:metabolism*; D010455:Peptides / Q000032:analysis; D051381:Rats; D011919:Rats, Inbred Strains; D014316:Tritium
D007457:Iodine Radioisotopes; D010455:Peptides; D014316:Tritium; D009496:Neurotensin