Cholecystokinin and human intestinal permeability.

The effect of intravenous cholecystokinin (CCK) on intestinal permeability in normal subjects and patients after cholecystectomy has been studied by measuring the fraction of orally administered lactulose excreted in the urine. CCK induced a marked increase in lactulose excretion in normal subjects when given in a hyperosmolar solution (49.4 mg lactulose during 5 h rising to 114.3 mg with CCK, p less than 0.001). CCK failed to affect lactulose excretion when given to normal subjects in an isosmolar solution, and also when given to post-cholecystectomy patients in either hyper- or isosmolar solutions. The 'CCK effect' is therefore related to gallbladder emptying. It is suggested that conjugated bile acids released following gallbladder contraction can affect intestinal permeability by enhancing the action of hypertonic solutions on the small intestinal mucosa.