Source of the fluid component of secretions from tracheal submucosal glands in cats

Abstract

The idea that the fluid component of cat tracheal submucosal gland secretions is produced by Na-linked secretion of Cl was tested. Gland secretion was stimulated with phenylephrine; gland fluid flow, net salt movement, and output of 35SO4-labeled macromolecules were measured. With CI, I, NO3, or Br as the major anion, phenylephrine caused equal increases in gland flow and output of 35S-labeled macromolecules while increasing net transepithelial 22Na movement from 0 to about 10 mu eq X cm-2 X h-1. With the impermeant gluconate as a major anion, phenylephrine caused the same increase in output of 35S label, a smaller increase in gland flow, and had no effect on net 22Na movement. Short circuiting in the presence of Cl, or high concentrations of the loop diuretics, furosemide or bumetanide, did not alter the actions of phenylephrine. Ouabain or replacement of Na by choline or Li abolished all secretory effects of phenylephrine. We conclude that active Cl secretion is not responsible for the transepithelial flows of salt and water induced by phenylephrine. Instead, these flows may be secondary to the release of osmotically active components of the secretory granules.