Mechanosensitivity of an epithelial Na+ channel in planar lipid bilayers

Release from Ca2+ block

Iskander I. Ismailov, Bakhram K. Berdiev, Vadim Gh Shlyonsky, Dale J. Benos

Research output: Contribution to journalArticle

45 Citations (Scopus)

Abstract

A family of novel epithelial Na+ channels (ENaCs) have recently been cloned from several different tissues. Three homologous subunits (α, β, γ- ENaCs) form the core conductive unit of Na+ -selective, amiloride-sensitive channels that are found in epithelia. We here report the results of a study assessing the regulation of α, β, γ-rENaC by Ca2+ in planar lipid bilayers. Buffering of the bilayer bathing solutions to [Ca2+] <1 nM increased single-channel open probability by fivefold. Further investigation of this phenomenon revealed that Ca2+ ions produced a voltage-dependent block, affecting open probability but not the unitary conductance of ENaC. Imposing a hydrostatic pressure gradient across bilayers containing α,β,γ- rENaC markedly reduced the sensitivity of these channels to inhibition by [Ca2+]. Conversely, in the nominal absence of Ca2+, the channels lost their sensitivity to mechanical stimulation. These results suggest that the previously observed mechanical activation of ENaCs reflects a release of the channels from block by Ca2+.

Original languageEnglish
Pages (from-to)1182-1192
Number of pages11
JournalBiophysical Journal
Volume72
Issue number3
Publication statusPublished - Mar 1997
Externally publishedYes

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Epithelial Sodium Channels
Lipid Bilayers
Hydrostatic Pressure
Amiloride
Epithelium
Ions

ASJC Scopus subject areas

  • Biophysics

Cite this

Ismailov, I. I., Berdiev, B. K., Shlyonsky, V. G., & Benos, D. J. (1997). Mechanosensitivity of an epithelial Na+ channel in planar lipid bilayers: Release from Ca2+ block. Biophysical Journal, 72(3), 1182-1192.

Mechanosensitivity of an epithelial Na+ channel in planar lipid bilayers : Release from Ca2+ block. / Ismailov, Iskander I.; Berdiev, Bakhram K.; Shlyonsky, Vadim Gh; Benos, Dale J.

In: Biophysical Journal, Vol. 72, No. 3, 03.1997, p. 1182-1192.

Research output: Contribution to journalArticle

Ismailov, II, Berdiev, BK, Shlyonsky, VG & Benos, DJ 1997, 'Mechanosensitivity of an epithelial Na+ channel in planar lipid bilayers: Release from Ca2+ block', Biophysical Journal, vol. 72, no. 3, pp. 1182-1192.
Ismailov II, Berdiev BK, Shlyonsky VG, Benos DJ. Mechanosensitivity of an epithelial Na+ channel in planar lipid bilayers: Release from Ca2+ block. Biophysical Journal. 1997 Mar;72(3):1182-1192.
Ismailov, Iskander I. ; Berdiev, Bakhram K. ; Shlyonsky, Vadim Gh ; Benos, Dale J. / Mechanosensitivity of an epithelial Na+ channel in planar lipid bilayers : Release from Ca2+ block. In: Biophysical Journal. 1997 ; Vol. 72, No. 3. pp. 1182-1192.
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