Effect of Osmotic Gradients on Water Transport, Hydrogen Ion and Chloride Ion Production in the Resting and Secreting Stomach

Abstract

The Cl of HC1 may be secreted by the surface epithelial cells (SEC) and the H by the parietal cells. Since water transport is governed by the osmotic gradient between lumen and interstitial fluid resulting from this H and Cl ion secretion, this theory implies that a small osmotic gradient across the SEC should produce considerable water transport. In a chambered gastric segment with intact blood supply, application of hypertonic salt solns. to the resting mucosa produced little water transport but the water output was high during secretion. Perhaps the SEC permeability was increased during secretion. 0.32 [image] NaCl caused approx. the same output of water and H as 0.16 [image] NaCl. More hypertonic fluids had no effect or decreased the water, H and Cl output. An isotonic gradient across the SEC causes no appreciable water transport in the resting or secreting stomach. The hypothesis that Cl is secreted by the SEC and H by the parietal cells is untenable if it is assumed that water transport results from an osmotic gradient.