Radioimmunoassay of cholecystokinin in human plasma.
A sensitive radioimmunoassay for cholecystokinin (CCK) has been developed. Porcine CCK-33 was labelled by conjugation with 125I-hydroxyphenyl-propionic acid succinimide ester. Antibodies were raised against porcine CCK-33 covalently coupled to egg albumin. Plasma samples were extracted with 96% ethanol prior to assay. Free and bound hormone were separated by dextran-coated charcoal. The antibodies bound CCK-8 and CCK-33 with equimolar potency. The assay detection limit was 1 pmol/l plasma. Within and between assay coefficients of variation were +/- 12.7 and 13.0% at mean plasma CCK concentrations of 13.2 and 13.6 pmol/l. The concentration of CCK in 47 normal fasting subjects ranged from undetectable to 22 pmol/l. Ingestion of a mixed meal in 9 normal subjects increased the plasma concentration from 8.3 +/- 2.5 S.E. to 24.4 +/- 6.5 pmol/l.
D000818:Animals; D000917:Antibody Formation; D000918:Antibody Specificity; D002766:Cholecystokinin / Q000097:blood*; D004386:Duodenum / Q000032:analysis; D006801:Humans; D007413:Intestinal Mucosa / Q000032:analysis; D011817:Rabbits / Q000276:immunology; D011863:Radioimmunoassay / Q000379:methods; D013552:Swine
D002766:Cholecystokinin