Kir2.3 isoform confers pH sensitivity to heteromeric Kir2.1/Kir2.3 channels in HEK293 cells

Viviana Muñoz, Ravi Vaidyanathan, Elena G. Tolkacheva, Amit S. Dhamoon, Steven M. Taffet, Justus M B Anumonwo

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

Background: Data on pH regulation of the cardiac potassium current IK1 suggest species-dependent differences in the molecular composition of the underlying Kir2 channel proteins. Objective: The purpose of this study was to test the hypothesis that the presence of the Kir2.3 isoform in heterotetrameric channels modifies channel sensitivity to pH. Methods: Voltage clamp was performed on HEK293 cells stably expressing guinea pig Kir2.1 and/or Kir2.3 isoforms and on sheep cardiac ventricular myocytes at varying extracellular pH (pHo) and in the presence of CO2 to determine the sensitivity of macroscopic currents to pH. Single-channel activity was recorded from the HEK293 stables to determine the mechanisms of the changes in whole cell current. Results: Biophysical characteristics of whole-cell and single-channel currents in Kir2.1/Kir2.3 double stables displayed properties attributable to isoform heteromerization. Whole-cell Kir2.1/Kir2.3 currents rectified in a manner reminiscent of Kir2.1 but were significantly inhibited by extracellular acidification in the physiologic range (pKa ∼ 7.4). Whole-cell currents were more sensitive to a combined extracellular and intracellular acidification produced by CO2. At pHo = 6.0, unitary conductances of heteromeric channels were reduced. Ovine cardiac ventricular cell IK1 was pHo and CO2 sensitive, consistent with the expression of Kir2.1 and Kir2.3 in this species. Conclusion: Kir2.1 and Kir2.3 isoforms form heteromeric channels in HEK293. The presence of Kir2.3 subunit(s) in heteromeric channels confers pH sensitivity to the channels. The single and double stable cells presented in this study are useful models for studying physiologic regulation of heteromeric Kir2 channels in mammalian cells.

Original languageEnglish (US)
Pages (from-to)487-496
Number of pages10
JournalHeart Rhythm
Volume4
Issue number4
DOIs
StatePublished - Apr 1 2007

Fingerprint

HEK293 Cells
Protein Isoforms
Sheep
Kir2.1 channel
Cardiac Myocytes
Potassium
Guinea Pigs
Proteins

Keywords

  • Heteromerization
  • I
  • Kir2.1
  • Kir2.3
  • pH sensitivity

Cite this

Kir2.3 isoform confers pH sensitivity to heteromeric Kir2.1/Kir2.3 channels in HEK293 cells. / Muñoz, Viviana; Vaidyanathan, Ravi; Tolkacheva, Elena G.; Dhamoon, Amit S.; Taffet, Steven M.; Anumonwo, Justus M B.

In: Heart Rhythm, Vol. 4, No. 4, 01.04.2007, p. 487-496.

Research output: Contribution to journalArticle

Muñoz, V, Vaidyanathan, R, Tolkacheva, EG, Dhamoon, AS, Taffet, SM & Anumonwo, JMB 2007, 'Kir2.3 isoform confers pH sensitivity to heteromeric Kir2.1/Kir2.3 channels in HEK293 cells', Heart Rhythm, vol. 4, no. 4, pp. 487-496. https://doi.org/10.1016/j.hrthm.2006.12.033
Muñoz, Viviana ; Vaidyanathan, Ravi ; Tolkacheva, Elena G. ; Dhamoon, Amit S. ; Taffet, Steven M. ; Anumonwo, Justus M B. / Kir2.3 isoform confers pH sensitivity to heteromeric Kir2.1/Kir2.3 channels in HEK293 cells. In: Heart Rhythm. 2007 ; Vol. 4, No. 4. pp. 487-496.
@article{fe5ebf9a19f24e30bd4225d5309fa2fb,
title = "Kir2.3 isoform confers pH sensitivity to heteromeric Kir2.1/Kir2.3 channels in HEK293 cells",
abstract = "Background: Data on pH regulation of the cardiac potassium current IK1 suggest species-dependent differences in the molecular composition of the underlying Kir2 channel proteins. Objective: The purpose of this study was to test the hypothesis that the presence of the Kir2.3 isoform in heterotetrameric channels modifies channel sensitivity to pH. Methods: Voltage clamp was performed on HEK293 cells stably expressing guinea pig Kir2.1 and/or Kir2.3 isoforms and on sheep cardiac ventricular myocytes at varying extracellular pH (pHo) and in the presence of CO2 to determine the sensitivity of macroscopic currents to pH. Single-channel activity was recorded from the HEK293 stables to determine the mechanisms of the changes in whole cell current. Results: Biophysical characteristics of whole-cell and single-channel currents in Kir2.1/Kir2.3 double stables displayed properties attributable to isoform heteromerization. Whole-cell Kir2.1/Kir2.3 currents rectified in a manner reminiscent of Kir2.1 but were significantly inhibited by extracellular acidification in the physiologic range (pKa ∼ 7.4). Whole-cell currents were more sensitive to a combined extracellular and intracellular acidification produced by CO2. At pHo = 6.0, unitary conductances of heteromeric channels were reduced. Ovine cardiac ventricular cell IK1 was pHo and CO2 sensitive, consistent with the expression of Kir2.1 and Kir2.3 in this species. Conclusion: Kir2.1 and Kir2.3 isoforms form heteromeric channels in HEK293. The presence of Kir2.3 subunit(s) in heteromeric channels confers pH sensitivity to the channels. The single and double stable cells presented in this study are useful models for studying physiologic regulation of heteromeric Kir2 channels in mammalian cells.",
keywords = "Heteromerization, I, Kir2.1, Kir2.3, pH sensitivity",
author = "Viviana Mu{\~n}oz and Ravi Vaidyanathan and Tolkacheva, {Elena G.} and Dhamoon, {Amit S.} and Taffet, {Steven M.} and Anumonwo, {Justus M B}",
year = "2007",
month = "4",
day = "1",
doi = "10.1016/j.hrthm.2006.12.033",
language = "English (US)",
volume = "4",
pages = "487--496",
journal = "Heart Rhythm",
issn = "1547-5271",
publisher = "Elsevier",
number = "4",

}

TY - JOUR

T1 - Kir2.3 isoform confers pH sensitivity to heteromeric Kir2.1/Kir2.3 channels in HEK293 cells

AU - Muñoz, Viviana

AU - Vaidyanathan, Ravi

AU - Tolkacheva, Elena G.

AU - Dhamoon, Amit S.

AU - Taffet, Steven M.

AU - Anumonwo, Justus M B

PY - 2007/4/1

Y1 - 2007/4/1

N2 - Background: Data on pH regulation of the cardiac potassium current IK1 suggest species-dependent differences in the molecular composition of the underlying Kir2 channel proteins. Objective: The purpose of this study was to test the hypothesis that the presence of the Kir2.3 isoform in heterotetrameric channels modifies channel sensitivity to pH. Methods: Voltage clamp was performed on HEK293 cells stably expressing guinea pig Kir2.1 and/or Kir2.3 isoforms and on sheep cardiac ventricular myocytes at varying extracellular pH (pHo) and in the presence of CO2 to determine the sensitivity of macroscopic currents to pH. Single-channel activity was recorded from the HEK293 stables to determine the mechanisms of the changes in whole cell current. Results: Biophysical characteristics of whole-cell and single-channel currents in Kir2.1/Kir2.3 double stables displayed properties attributable to isoform heteromerization. Whole-cell Kir2.1/Kir2.3 currents rectified in a manner reminiscent of Kir2.1 but were significantly inhibited by extracellular acidification in the physiologic range (pKa ∼ 7.4). Whole-cell currents were more sensitive to a combined extracellular and intracellular acidification produced by CO2. At pHo = 6.0, unitary conductances of heteromeric channels were reduced. Ovine cardiac ventricular cell IK1 was pHo and CO2 sensitive, consistent with the expression of Kir2.1 and Kir2.3 in this species. Conclusion: Kir2.1 and Kir2.3 isoforms form heteromeric channels in HEK293. The presence of Kir2.3 subunit(s) in heteromeric channels confers pH sensitivity to the channels. The single and double stable cells presented in this study are useful models for studying physiologic regulation of heteromeric Kir2 channels in mammalian cells.

AB - Background: Data on pH regulation of the cardiac potassium current IK1 suggest species-dependent differences in the molecular composition of the underlying Kir2 channel proteins. Objective: The purpose of this study was to test the hypothesis that the presence of the Kir2.3 isoform in heterotetrameric channels modifies channel sensitivity to pH. Methods: Voltage clamp was performed on HEK293 cells stably expressing guinea pig Kir2.1 and/or Kir2.3 isoforms and on sheep cardiac ventricular myocytes at varying extracellular pH (pHo) and in the presence of CO2 to determine the sensitivity of macroscopic currents to pH. Single-channel activity was recorded from the HEK293 stables to determine the mechanisms of the changes in whole cell current. Results: Biophysical characteristics of whole-cell and single-channel currents in Kir2.1/Kir2.3 double stables displayed properties attributable to isoform heteromerization. Whole-cell Kir2.1/Kir2.3 currents rectified in a manner reminiscent of Kir2.1 but were significantly inhibited by extracellular acidification in the physiologic range (pKa ∼ 7.4). Whole-cell currents were more sensitive to a combined extracellular and intracellular acidification produced by CO2. At pHo = 6.0, unitary conductances of heteromeric channels were reduced. Ovine cardiac ventricular cell IK1 was pHo and CO2 sensitive, consistent with the expression of Kir2.1 and Kir2.3 in this species. Conclusion: Kir2.1 and Kir2.3 isoforms form heteromeric channels in HEK293. The presence of Kir2.3 subunit(s) in heteromeric channels confers pH sensitivity to the channels. The single and double stable cells presented in this study are useful models for studying physiologic regulation of heteromeric Kir2 channels in mammalian cells.

KW - Heteromerization

KW - I

KW - Kir2.1

KW - Kir2.3

KW - pH sensitivity

UR - http://www.scopus.com/inward/record.url?scp=34247224764&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=34247224764&partnerID=8YFLogxK

U2 - 10.1016/j.hrthm.2006.12.033

DO - 10.1016/j.hrthm.2006.12.033

M3 - Article

C2 - 17399639

AN - SCOPUS:34247224764

VL - 4

SP - 487

EP - 496

JO - Heart Rhythm

JF - Heart Rhythm

SN - 1547-5271

IS - 4

ER -