A cloned renal epithelial Na+ channel protein displays stretch activation in planar lipid bilayers

M. S. Awayda, I. I. Ismailov, B. K. Berdiev, D. J. Benos

Research output: Contribution to journalArticle

106 Citations (Scopus)

Abstract

We have previously cloned a bovine renal epithelial channel homologue (α- bENaC) belonging to the epithelial Na+ channel (ENaC) family. With the use of a rabbit nuclease-treated in vitro translation system, mRNA coding for α- bENaC was translated and the polypeptide products were reconstituted into liposomes. On incorporation into planar lipid bilayers, in vitro-translated α-bENaC protein 1) displayed voltage-independent Na+ channel activity with a single-channel conductance of 40 pS, 2) was mechanosensitive in that the single-channel open probability was maximally activated with a hydrostatic pressure gradient of 0.26 mmHg across the bilayer, 3) was blocked by low concentrations of amiloride [apparent inhibitory constant of amiloride (K(amil)) ≃ 150 nM], and 4) was cation selective with a Li+:Na+:K+ permselectivity of 2:1:0.14 under nonstretched conditions. These pharmacological and selectivity characteristics were altered to a lower amiloride affinity (K(amil) > 25 μM) and a lack of monovalent cation selectivity in the presence of a hydrostatic pressure gradient. This observation of stretch activation (SA) of α-bENaC was confirmed in dual electrode recordings of heterologously expressed α-bENaC whole cell currents in Xenopus oocytes swelled by the injection of 15 nl of a 100 mM KCl solution. We conclude that α-bENaC, and by analogy other ENaCs, represent a novel family of cloned SA channels.

Original languageEnglish
JournalAmerican Journal of Physiology - Cell Physiology
Volume268
Issue number6 37-6
Publication statusPublished - 1995
Externally publishedYes

Fingerprint

Epithelial Sodium Channels
lipid bilayers
Lipid bilayers
Amiloride
Lipid Bilayers
cations
Chemical activation
kidneys
Kidney
Hydrostatic Pressure
nucleases
Xenopus
Hydrostatic pressure
Pressure gradient
electrodes
polypeptides
Proteins
oocytes
proteins
rabbits

Keywords

  • amiloride
  • bovine
  • kidney
  • mechanosensitivity
  • sodium ion
  • Xenopus

ASJC Scopus subject areas

  • Clinical Biochemistry
  • Cell Biology
  • Physiology
  • Agricultural and Biological Sciences(all)

Cite this

A cloned renal epithelial Na+ channel protein displays stretch activation in planar lipid bilayers. / Awayda, M. S.; Ismailov, I. I.; Berdiev, B. K.; Benos, D. J.

In: American Journal of Physiology - Cell Physiology, Vol. 268, No. 6 37-6, 1995.

Research output: Contribution to journalArticle

Awayda, M. S. ; Ismailov, I. I. ; Berdiev, B. K. ; Benos, D. J. / A cloned renal epithelial Na+ channel protein displays stretch activation in planar lipid bilayers. In: American Journal of Physiology - Cell Physiology. 1995 ; Vol. 268, No. 6 37-6.
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