title: Metabolism of 125I-labelled trypsin in man: evidence of recirculation.
abstract: 125I-labelled human trypsin metabolism has been investigated in man. Three subjects received 125I-trypsin and 131I-albumin intravenously. Against a background secretin infusion (1 U/kg/h), trypsin decayed biexponentially from the serum with half-lives of 17.5, 21, and 24 minutes for the rapid disappearance phase and 520, 540, and 560 minutes for the slow phase. Between 13% and 38% of the 125I injected was recovered from duodenal juice aspirated continously over 300 minutes. In contrast, less than 1% of the 131I-albumin injected was recovered. When bile and pure pancreatic juice were collected at endoscopic retrograde cholangiopancreatography after intravenous 125I-trypsin in a fourth subject 125I radioactivity was found to be secreted via both these routes. After 125I-trypsin infusion into the duodenum 11% of the total dose was found to be present in the circulation after 75 minutes. These results support the concept that recirculation of trypsin exists in man.
mesh_terms: D000328:Adult; D000418:Albumins / Q000378:metabolism; D001646:Bile / Q000378:metabolism; D004386:Duodenum / Q000378:metabolism; D005260:Female; D006801:Humans; D007408:Intestinal Absorption; D007419:Intestinal Secretions / Q000378:metabolism; D007457:Iodine Radioisotopes; D008297:Male; D008875:Middle Aged; D014357:Trypsin / Q000097:blood / Q000378:metabolism*
chemical_list: D000418:Albumins; D007457:Iodine Radioisotopes; D014357:Trypsin