Cation selectivity of the apical membrane of the turtle colon. Sodium entry in the presence of lithium

S. M. Thompson, D. C. Dawson

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

Exposure of the apical surface of the isolated turtle colon to Li produced a marked transient in short-circuit current (I(sc)) and total tissue conductance (G(T)) which was abolished by amiloride but was unaffected by ouabain or by removing Na or Cl from the mucosal bathing solution. Despite marked changes in I(sc), Na uptake across the apical membrane was a linear function of time during exposure to Li-containing solutions, and except at very high Li concentrations, the initial rate of Na uptake, J(i)(Na) was identical to its pre-Li value. In the presence of Li, however, J(i)(Na) was significantly less than the total I(sc). The apparent 'transference number' for Na in the apical membranes was a function of the Li:Na concentration ratio in the mucosal bathing solution. These results suggest that Li can carry substantial amounts of current through amiloride-sensitive channels in the apical membrane of the colon without having any effect on the rate coefficient for Na entry. This behavior is not consistent with 'competition' of Na and Li for a membrane 'carrier' but rather suggests that the Na entry mechanism may be a population of pores or channels through which Na and Li may pass with negligible interaction.

Original languageEnglish (US)
Pages (from-to)269-282
Number of pages14
JournalJournal of General Physiology
Volume72
Issue number3
StatePublished - 1978
Externally publishedYes

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Turtles
Lithium
Cations
Colon
Sodium
Membranes
Amiloride
Ouabain
Population

ASJC Scopus subject areas

  • Physiology

Cite this

Cation selectivity of the apical membrane of the turtle colon. Sodium entry in the presence of lithium. / Thompson, S. M.; Dawson, D. C.

In: Journal of General Physiology, Vol. 72, No. 3, 1978, p. 269-282.

Research output: Contribution to journalArticle

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