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Potassium Transport by Flounder Intestinal Mucosa
American Journal of Physiology - Renal Physiology
  • Raymond A. Frizzell
  • Dan R. Halm, Wright State University - Main Campus
  • Mark W. Musch
  • Christopher P. Stewart
  • Michael Field
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We studied the mechanisms of K transport across an epithelium in which NaCl absorption is mediated primarily by Na/K/Cl cotransport at the apical membrane. Rubidium served as a reliable K substitute; under control conditions, both K and Rb were actively secreted. During secretion, K (Rb) enters across the basolateral membrane via the Na/K pump and exits across the apical membrane through K conductance pathways, since serosal ouabain or mucosal barium abolished K secretion, mucosal furosemide or Cl-free media blocked K secretion by interfering with access of Na to the pump, and elevated mucosal solution [K] or [Rb] depolarized the apical membrane electrical potential difference. Mucosal Ba unmasked active Rb absorption that could be blocked by mucosal furosemide. These findings illustrate active K absorption and secretion across an epithelium that comprises a single cell type in which opposing K fluxes across the apical membrane are mediated by Na/K/Cl cotransport entry and conductive K exit. The direction of transepithelial K transport is determined by the relative activities of these pathways.

Citation Information
Raymond A. Frizzell, Dan R. Halm, Mark W. Musch, Christopher P. Stewart, et al.. "Potassium Transport by Flounder Intestinal Mucosa" American Journal of Physiology - Renal Physiology Vol. 246 Iss. 6 (1984) p. F946 - F951 ISSN: 1931857X
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