Basal plasma cholecystokinin levels in digestive diseases: Comparison between CCK-8 like bioactivity by bioassay and CCK immunoreactivity by radioimmunoassay

Basal plasma cholecystokinin levels were measured by a bioassay using dispersed rat pancreatic acini in various digestive diseases and compared with corresponding values by CCK-8 specific radioimmunoassay. The mean basal level in healthy volunteers was 0.40±0.06pM. The basal level in liver cirrhosis was significantly elevated to 0.92±0.14pM. The patients with cholestasis, that is, primary biliary cirrhosis and obstructive jaundice due to choledocholithiasis, bile duct cancer or lymph node metastase, had markedly increased basal plasma CCK-8 like bioactivities from 1.88pM to more than 25pM. These CCK bioactivities were not correlative with CCK immunoreactivities. It was concluded not only that basal plasma CCK in patients with bile flow disturbance were truely increased, but also that interfering substances of the bioassay might appear in the plasma of these patients.