title: Radioimmunoassay of secretin in plasma.
abstract: A sensitive, specific and reproducible radioimmunoassay for secretin is described. Antibodies were readily produced against low microgram quantities of synthetic secretin. The secretin antibodies did not cross-react with the structurally similar G.I.P., V.I.P., or glucagon. Synthetic secretin was iodinated using Chloramine "T" and purified by a two-state procedure incorporating gel filtration and radient elution from a cation exchange column. Plasma samples were found to produce variable interference in the assay necessitating the incorporation of secretin-free "blands" for each patient's plasma. Production of secretin-free plasma was by incubation of plasma samples at 37 degrees C for 96 hours. The sensitivity of the assay was 12.5-25 pg/ml. Normal fasting secretin levels were 21 +/- S.E. 7 pg/ml. A mean rise in plasma secretin to 220 pg/ml was observed after intraduodenal acidification.
mesh_terms: D000818:Animals; D007611:Aprotinin; D001386:Azides; D004355:Drug Stability; D004386:Duodenum / Q000502:physiology; D006801:Humans; D008832:Microchemistry; D011817:Rabbits; D011863:Radioimmunoassay / Q000379:methods; D012633:Secretin / Q000097:blood* / Q000302:isolation & purification
chemical_list: D001386:Azides; D012633:Secretin; D007611:Aprotinin