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Horm Metab Res 1976; 8(5): 361-365
DOI: 10.1055/s-0028-1093614
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© Georg Thieme Verlag KG Stuttgart · New York

Radioimmunoassay of Secretin in Plasma

D. J. Byrnes [*] , J. P. Marjason [*]
  • Garvan Institute of Medical Research and Bruce Hall Dept. Gastroenterology, St. Vincent's Hospital, Sydney, Australia
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Publication History

Publication Date:
23 December 2008 (online)

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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-stage procedure incorporating gel filtration and gradient elution from a cation-exchange column. Plasma samples were found to produce variable interference in the assay necessitating the incorporation of secretin-free "blanks" for each patient's plasma. Production of secretin-free plasma was by incubation of plasma samples at 37°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.

Key words

Secretin - Radioimmunoassay - Iodination - Antibodies - Plasma Interference - Duodenal Acidification

1 Supported by Bruce Hall Trust