A Method for the Standardization of Cholecystokinin in Vitro

Publisher Website
Google Scholar
Abstract
Summary.: A method is described for the standardization of cholecystokinin in vitro, correlated with in vivo experiments, and with concurrent testing of the effect on the intestine of impure preparations. The usual intestinal bath technique is used; the gallbladder is placed in one cuvette and a piece of the intestine in another, both organs being taken from the guinea‐pig. The contractions are recorded and read off in mm on a scale.Histamine and choline derivatives, as well as acid and alkaline buffer solutions, are found to produce contractions of both the intestine and the gallbladder in vitro. Ammonium salts also cause contractions of the gallbladder. Even if these sources of error are eliminated, crude preparations of cholecystokinin still cause some intestinal contraction. This effect disappears when the preparations are purified further.In in vivo experiments, the injection of cholecystokinin in the cat under nembutal anesthesia is found to result in a flow of greenish‐black bile from the gallbladder, whereas the above‐mentioned substances in non‐toxic doses cause no reaction.