pH Alterations "Reset" Ca2+ Sensitivity of Brain Na+ Channel 2, a Degenerin/Epithelial Na+ Ion Channel, in Planar Lipid Bilayers

Bakhrom K. Berdiev, Timothy B. Mapstone, James M. Markert, G. Yancey Gillespie, Jason Lockhart, Catherine M. Fuller, Dale J. Benos

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

Members of the degenerin/epithelial Na+ channel superfamily of ion channels subserve many functions, ranging from whole body sodium handling to mechanoelectrical transduction. We studied brain Na+ channel 2 (BNaC-2) in planar lipid bilayers to examine its single channel properties and regulation by Ca2+. Upon incorporation of vesicles made from membranes of oocytes expressing either wild-type (WT) BNaC-2 or BNaC-2 with a gain-of-function (GF) point mutation (G433F), functional channels with different properties were obtained. WT BNaC-2 resided in a closed state with short openings, whereas GF BNaC-2 was constitutively activated; a decrease in the pH in the trans compartment of the bilayer activated WT BNaC-2 and decreased its permeability for Na+ over K+. Moreover, these maneuvers made the WT channel more resistant to amiloride. In contrast, GF BNaC-2 did not respond to a decrease in pH, and its amiloride sensitivity and selectivity for Na+ over K+ were unaffected by this pH change. Buffering the bathing solutions with EGTA to reduce the free [Ca 2+] to 2+ blocked both WT and GF BNaC-2 in a dose- and voltage-dependent fashion; single channel conductances were unchanged. A drop in pH reduced the ability of Ca2+ to inhibit these channels. These results show that BNaC-2 is an amiloride-sensitive sodium channel and suggest that pH activation of these channels could be, in part, a consequence of H+ "interference" with channel regulation by Ca2+.

Original languageEnglish
Pages (from-to)38755-38761
Number of pages7
JournalJournal of Biological Chemistry
Volume276
Issue number42
DOIs
Publication statusPublished - Oct 19 2001
Externally publishedYes

Fingerprint

Degenerin Sodium Channels
Epithelial Sodium Channels
Lipid bilayers
Lipid Bilayers
Ion Channels
Brain
Amiloride
Sodium Channels
Egtazic Acid
Point Mutation
Oocytes
Permeability

ASJC Scopus subject areas

  • Biochemistry

Cite this

Berdiev, B. K., Mapstone, T. B., Markert, J. M., Gillespie, G. Y., Lockhart, J., Fuller, C. M., & Benos, D. J. (2001). pH Alterations "Reset" Ca2+ Sensitivity of Brain Na+ Channel 2, a Degenerin/Epithelial Na+ Ion Channel, in Planar Lipid Bilayers. Journal of Biological Chemistry, 276(42), 38755-38761. https://doi.org/10.1074/jbc.M107266200

pH Alterations "Reset" Ca2+ Sensitivity of Brain Na+ Channel 2, a Degenerin/Epithelial Na+ Ion Channel, in Planar Lipid Bilayers. / Berdiev, Bakhrom K.; Mapstone, Timothy B.; Markert, James M.; Gillespie, G. Yancey; Lockhart, Jason; Fuller, Catherine M.; Benos, Dale J.

In: Journal of Biological Chemistry, Vol. 276, No. 42, 19.10.2001, p. 38755-38761.

Research output: Contribution to journalArticle

Berdiev, BK, Mapstone, TB, Markert, JM, Gillespie, GY, Lockhart, J, Fuller, CM & Benos, DJ 2001, 'pH Alterations "Reset" Ca2+ Sensitivity of Brain Na+ Channel 2, a Degenerin/Epithelial Na+ Ion Channel, in Planar Lipid Bilayers', Journal of Biological Chemistry, vol. 276, no. 42, pp. 38755-38761. https://doi.org/10.1074/jbc.M107266200
Berdiev, Bakhrom K. ; Mapstone, Timothy B. ; Markert, James M. ; Gillespie, G. Yancey ; Lockhart, Jason ; Fuller, Catherine M. ; Benos, Dale J. / pH Alterations "Reset" Ca2+ Sensitivity of Brain Na+ Channel 2, a Degenerin/Epithelial Na+ Ion Channel, in Planar Lipid Bilayers. In: Journal of Biological Chemistry. 2001 ; Vol. 276, No. 42. pp. 38755-38761.
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abstract = "Members of the degenerin/epithelial Na+ channel superfamily of ion channels subserve many functions, ranging from whole body sodium handling to mechanoelectrical transduction. We studied brain Na+ channel 2 (BNaC-2) in planar lipid bilayers to examine its single channel properties and regulation by Ca2+. Upon incorporation of vesicles made from membranes of oocytes expressing either wild-type (WT) BNaC-2 or BNaC-2 with a gain-of-function (GF) point mutation (G433F), functional channels with different properties were obtained. WT BNaC-2 resided in a closed state with short openings, whereas GF BNaC-2 was constitutively activated; a decrease in the pH in the trans compartment of the bilayer activated WT BNaC-2 and decreased its permeability for Na+ over K+. Moreover, these maneuvers made the WT channel more resistant to amiloride. In contrast, GF BNaC-2 did not respond to a decrease in pH, and its amiloride sensitivity and selectivity for Na+ over K+ were unaffected by this pH change. Buffering the bathing solutions with EGTA to reduce the free [Ca 2+] to 2+ blocked both WT and GF BNaC-2 in a dose- and voltage-dependent fashion; single channel conductances were unchanged. A drop in pH reduced the ability of Ca2+ to inhibit these channels. These results show that BNaC-2 is an amiloride-sensitive sodium channel and suggest that pH activation of these channels could be, in part, a consequence of H+ {"}interference{"} with channel regulation by Ca2+.",
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AU - Mapstone, Timothy B.

AU - Markert, James M.

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AU - Benos, Dale J.

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