Pancreatic epithelium is permeable to sucrose and inulin across secretory cells

The pancreatic epithelium is permeable to both sucrose and inulin and becomes more permeable when protein secretion by the gland is stimulated. Because these molecules are not thought to enter cells, it has been assumed that their movement across the epithelium from interstitial to ductal fluid, as well as the increase in that flux that is observed during augmented protein secretion, is due to their passage through paracellular shunts. In the present experiments we have considered the alternative possibility that sucrose and inulin travel through the cells of the secretory epithelium instead of, or in addition to, their passage through paracellular shunts. The data support this view and suggest that the pancreas is unusually permeable to water soluble molecules of substantial size by means of a transcellular pathway.