In frog fundic mucosae mounted in Ussing chambers, exposure to luminal 1 M NaCl for 10 min caused a sharp immediate decrease in potential difference, resistance, short circuit current, and acid secretion, but within 4-6 h these readings had returned toward control values. After initial severe destruction of surface epithelial cells, gradual morphologic restitution occurred within 4-6 h. A Ca2+-free nutrient solution and 4 mM ethylenediaminetetraacetic acid administered after injury prevented both physiologic and morphologic restitution. A Ca2+-free nutrient solution administered alone after injury prevented physiologic recovery, but although narrow gaps and lack of tight junctions were found between some cells, there was near-complete epithelial cell coverage. The addition of 2 mM Ca2+ to these tissues 3 h after injury effected rapid recovery of electrophysiologic parameters and a complete closure of the intercellular spaces. Cytochalasin B (3 X 10(-3) M nutrient) prevented physiologic recovery and mucosal restitution. Neither cycloheximide nor colchicine had any effect on the normal process of restitution. Autoradiography of [3H]thymidine incorporation showed no increase in labeling within 4 h of hyperosmolar injury. We conclude that adequate Ca2+ is required for complete restitution of gastric mucosa after hyperosmolar injury, and that restitution occurs by migration of persisting viable gastric pit cells.

SUMMARY1. The role of nerves in periodic secretion of the pancreas and the stomach in relation to the motility of the upper gastrointestinal tract was studied in conscious fasting dogs which had previously been provided with chronic gastric and pancreatic fistulae and a Heidenhain pouch.2. Both atropine and pentolinium abolished the periodic increase in gastric and pancreatic secretion and motility of the gut.3. Bilateral cervical vagal blockade with lidocaine reduced the motility of the stomach, the duodenum and the pouch preceding their peaks, but the motility at the peaks remained unchanged except in the case of the stomach.4. Pancreatic secretion preceding its peak was also decreased by vagal blockade but that at the peak was not significantly different from the control peak.5. Periodic pepsin secretion, from both the fistula and pouch, was decreased by vagal blockade.6. It is concluded that the secretion and motility of the upper gut in fasting dogs is controlled by periodic activity of the vagus and intrinsic nerves.

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