Control of potassium transport by turtle colon: Role of membrane potential

D. R. Halm, D. C. Dawson

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2 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)
JournalAmerican Journal of Physiology - Cell Physiology
Issue number1
Publication statusPublished - 1984
Externally publishedYes


ASJC Scopus subject areas

  • Cell Biology
  • Clinical Biochemistry
  • Physiology

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