WATER AND ION SHIFTS IN MOUSE INTESTINAL-CELLS FOLLOWING VIP STIMULATION

The cytoplasmic water content and the concentrations of Cl-, Na+ and K + were measured by X-ray microanalysis and cryoelectron microscopy in mouse jejunal crypt enterocytes, Paneth cells, villus enterocytes, smo oth muscle cells and in the basal lamina lining the crypt epithelium. Values found in controls were compared with those measured after in vi vo stimulation of intestinal electrolyte secretion by vasoactive intes tinal polypeptide (VIP). Na+ extrusion via the Na+/K+ pump appears to be rate-limiting for electrolyte secretion through crypt enterocytes i n this model. VIP depolarizes smooth muscle cells and affects the ion distribution in villus enterocytes.