title: To extract or not to extract in secretin radioimmunoassay?
abstract: The importance of an ethanol extraction procedure in the radioimmunoassay of plasma secretin was investigated. The extraction step led to a higher assay sensitivity of 0.35 fmol/ml, compared to 5.93 fmol/ml using unextracted samples. The rise of plasma secretin after infusion of a low dose of secretin (1 pmol.kg-1.h-1) in 10 healthy humans was only detected after sample extraction. Higher doses (3 and 9 pmol.kg-1.h-1) resulted in increments of plasma IRS (immunoreactive secretin), which could be recorded both with and without sample extraction. After a steak meal 7 of 10 subjects showed a significant increase of plasma secretin assaying extracted plasma samples. The secretin release occurred in spikes. The mean increase of plasma IRS in this group was 0.6 fmol/ml, the mean maximal secretin release above basal was 2.3 fmol/ml. Without sample extraction, plasma secretin was not significantly changed. We conclude that plasma samples should be extracted in order to detect physiological postprandial secretin release.
authors.affiliation: Outpatient Clinic, University Hospital Basel, Switzerland.
authors.forename: M
authors.initials: M
authors.lastname: Fried
authors.forename: C
authors.initials: C
authors.lastname: Schulthess
authors.forename: C
authors.initials: C
authors.lastname: Beglinger
authors.forename: B
authors.initials: B
authors.lastname: Müller
authors.forename: K
authors.initials: K
authors.lastname: Gyr
mesh_terms: D000818:Animals; D005502:Food; D006801:Humans; D011817:Rabbits; D011863:Radioimmunoassay / Q000379:methods; D012633:Secretin / Q000097:blood*
chemical_list: D012633:Secretin