title: Solid-phase radioimmunoassay and chemiluminoimmunoassay for somatostatin in unextracted rat plasma.
abstract: Measurement of somatostatin (SS) in small microliter volumes of rat plasma obtained from the hypophysial portal circulation would be aided by a sensitive and robust technique not dependent on extraction. We have developed radioimmunoassay (RIA) and chemiluminoimmunoassay (CIA) for SS in unextracted rat plasma from a previously described solid-phase method in human plasma. Plasma SS was captured by primary antibody bound to second antibody coated polystyrene bead. After incubation the bead was washed and [125I]Tyr1-SS added. Following overnight incubation and washing, the bead was counted. The sensitivity for 50 microliters plasma was 11 pg/ml. Parallel displacement with abdominal portal and hypophysial portal plasma was demonstrated. For direct CIA, SS was labeled with acridinium and purified using 2 sequential gradient elutions on reversed-phase HPLC. Labeled SS performed satisfactorily in solution CIA, but did not bind well in solid-phase CIA. Hence, an indirect CIA using biotinylated SS and quantitation by acridinium labeled streptavidin was established with equivalent performance to solid-phase RIA. In summary, we have developed and validated sensitive and robust solid-phase RIA and indirect CIA for SS in unextracted rat plasma. This solid-phase method could serve as a universal system for the measurement of other neuropeptides in rat plasma.
authors.affiliation: Medical and Research Services, Huntington V.A. Medical Center, WV 257040, USA.
authors.forename: J W
authors.initials: JW
authors.lastname: Leidy
authors.forename: K L
authors.initials: KL
authors.lastname: Daniels
authors.forename: W J
authors.initials: WJ
authors.lastname: Millard
mesh_terms: D000818:Animals; D002851:Chromatography, High Pressure Liquid; D008297:Male; D011863:Radioimmunoassay; D051381:Rats; D017207:Rats, Sprague-Dawley; D013004:Somatostatin / Q000097:blood* / Q000378:metabolism*
chemical_list: D013004:Somatostatin