Assay of Secretin and Cholecystokinin Concentrates.

Abstract

The assay of secretin and CCK concentrates are affected by cannulation of the pancreatic duct and the gall bladder, respectively. The ratio of dosages of a vasodilatin-free standard concentrate (SI) to the test fraction yielding the same number of drops of pancreatic juice in a 10-min. interval is detd., and the value is taken as the secretin unitage contained in 1 mg. of test fraction. Similarly, the dosage ratio of this standard to the unknown giving the same gall bladder contraction is equated to the units of CCK per mg. of unknown. Good reproduciblity is obtained in a large number of dogs. The dose-response curves for CCK and their significance are discussed.