Control of potassium transport by turtle colon: role of membrane potential.

D. R. Halm, D. C. Dawson

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10 Scopus citations


To more clearly define the role of the transepithelial electrical potential difference (V m----s), potassium permeability, and sodium-potassium pump rate in transcellular potassium transport by isolated turtle colon, we measured transmural potassium fluxes under open-circuit conditions in the presence and absence of putative blockers of potassium transport: amiloride and barium. The results were consistent with the notion that V m----s is a major determinant of cellular potassium secretion, whereas active potassium absorption is insensitive to changes in V m----s. These observations suggest that "coupling" between colonic sodium absorption and potassium secretion in vivo could be due primarily to the effect of the lumen negative V m----s on transcellular secretory potassium flow. Amiloride-induced inhibition of potassium secretion appeared to be due to the reductions in V m----s and sodium-potassium pump rate that accompanied the inhibition of active sodium absorption.

Original languageEnglish (US)
Pages (from-to)C26-32
JournalThe American journal of physiology
Issue number1 Pt 1
StatePublished - Jul 1 1984

ASJC Scopus subject areas

  • Physiology (medical)


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