Primary site of the huge increase in resistance upon inhibition of gastric acid secretion with hypotonic secretory solution.

In summary, in this paper previous as well as some new results are presented for analysis. It has been shown for the in vitro frog gastric mucosa, with secretory solutions hypotonic relative to the nutrient solution, that inhibition of acid secretion produces a large increase in the transmucosal resistance, Rt. We have shown on the basis of electrophysiological findings that the large increase in Rt is due to an increase in the resistance of the pit and tubular lumina and that the primary factor in this increase is a decrease in luminal area. We have shown that the low transmucosal resistance of the fundus (the acid-secreting portion of the stomach) under standard conditions is due to a low resistance of the lumen-tubular (acid-secreting) cell pathway and that the parallel pathways have high resistances. The latter conclusion is important in deciding among the various models for the mechanism of acid secretion. The histological findings are qualitatively predicted by the electrophysiological results. The limitations of present histological techniques for a quantitative determination of the area of the lumina have also been discussed.