Active sodium transport by turtle colon via an electrogenic Na-K exchange pump

Kevin L. Kirk, Dan R. Halm, David C. Dawson

Research output: Contribution to journalArticle

57 Citations (Scopus)

Abstract

Active sodium absorption by a variety of epithelia is abolished by ouabain, but the obligatory coupling between the movement of sodium and potassium expected from a basolateral (Na+ + K+) ATPase has not been convincingly demonstrated1. According to the model of Koefoed-Johnsen and Ussing2, the asymmetric cation selectivities of the apical and basolateral membranes prevent basolateral Na-K exchange from being expressed as opposing transmural ion flows. An additional consequence of this asymmetry is that the short-circuit current (ISC) cannot be identified with the current through the sodium-potassium pump. We used the polyene antibiotic, amphotericin-B, to reduce the resistance and the cation selectivity of the apical membrane of isolated turtle colon so that the basolateral membrane current could be dissected into two components: one through a barium-sensitive potassium channel and another which represents the current associated with ouabain-sensitive, electrogenic, Na-K exchange. Comparison of cation fluxes and short circuit current indicates that in these conditions active sodium absorption is entirely attributable to an electrogenic Na-K pump with a stoichiometry of approximately 3Na:2K.

Original languageEnglish (US)
Pages (from-to)237-239
Number of pages3
JournalNature
Volume287
Issue number5779
DOIs
StatePublished - 1980
Externally publishedYes

Fingerprint

Turtles
Active Biological Transport
Cations
Colon
Sodium
Ouabain
Membranes
Polyenes
Sodium-Potassium-Exchanging ATPase
Potassium Channels
Amphotericin B
Barium
Potassium
Epithelium
Ions
Anti-Bacterial Agents

ASJC Scopus subject areas

  • General

Cite this

Active sodium transport by turtle colon via an electrogenic Na-K exchange pump. / Kirk, Kevin L.; Halm, Dan R.; Dawson, David C.

In: Nature, Vol. 287, No. 5779, 1980, p. 237-239.

Research output: Contribution to journalArticle

Kirk, Kevin L. ; Halm, Dan R. ; Dawson, David C. / Active sodium transport by turtle colon via an electrogenic Na-K exchange pump. In: Nature. 1980 ; Vol. 287, No. 5779. pp. 237-239.
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