Expression of intermediate-conductance, Ca2+-activated K+ channel (KCNN4) in H441 human distal airway epithelial cells

Stuart M. Wilson, Sean G. Brown, Niall McTavish, R. P. McNeill, E. M. Husband, Sarah K. Inglis, Richard E. Olver, M. T. Clunes

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Abstract

Electrophysiological studies of H441 human distal airway epithelial cells showed that thapsigargin caused a Ca2+-dependent increase in membrane conductance (GTot) and hyperpolarization of membrane potential (Vm). These effects reflected a rapid rise in cellular K+ conductance (GK) and a slow fall in amiloride-sensitive Na+ conductance (GNa). The increase in GTot was antagonized by Ba2+, a nonselective K+ channel blocker, and abolished by clotrimazole, a KCNN4 inhibitor, but unaffected by other selective K+ channel blockers. Moreover, 1-ethyl-2-benzimidazolinone (1-EBIO), which is known to activate KCNN4, increased GK with no effect on GNa. RT-PCR-based analyses confirmed expression of mRNA encoding KCNN4 and suggested that two related K+ channels (KCNN1 and KCNMA1) were absent. Subsequent studies showed that 1-EBIO stimulates Na+ transport in polarized monolayers without affecting intracellular Ca2+ concentration ([Ca2+]i), suggesting that the activity of KCNN4 might influence the rate of Na+absorption by contributing to GK. Transient expression of KCNN4 cloned from H441 cells conferred a Ca2+- and 1-EBIO-sensitive K+ conductance on Chinese hamster ovary cells, but this channel was inactive when [Ca2+]i was <0.2 μM. Subsequent studies of amiloride-treated H441 cells showed that clotrimazole had no effect on Vm despite clear depolarizations in response to increased extracellular K+ concentration ([K+]o). These findings thus indicate that KCNN4 does not contribute to Vm in unstimulated cells. The present data thus establish that H441 cells express KCNN4 and highlight the importance of GK to the control of Na+ absorption, but, because KCNN4 is quiescent in resting cells, this channel cannot contribute to resting GK or influence basal Na+ absorption.
Original languageEnglish
Pages (from-to)L957-L965
Number of pages9
JournalAmerican Journal of Physiology: Lung Celullar and Molecular Physiology
Volume291
Issue number5
DOIs
StatePublished - 9 Jun 2006

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Wilson, Stuart M.; Brown, Sean G.; McTavish, Niall; McNeill, R. P.; Husband, E. M.; Inglis, Sarah K.; Olver, Richard E.; Clunes, M. T. / Expression of intermediate-conductance, Ca2+-activated K+ channel (KCNN4) in H441 human distal airway epithelial cells.

In: American Journal of Physiology: Lung Celullar and Molecular Physiology, Vol. 291, No. 5, 09.06.2006, p. L957-L965.

Research output: Contribution to journalArticle

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title = "Expression of intermediate-conductance, Ca2+-activated K+ channel (KCNN4) in H441 human distal airway epithelial cells",
abstract = "Electrophysiological studies of H441 human distal airway epithelial cells showed that thapsigargin caused a Ca2+-dependent increase in membrane conductance (GTot) and hyperpolarization of membrane potential (Vm). These effects reflected a rapid rise in cellular K+ conductance (GK) and a slow fall in amiloride-sensitive Na+ conductance (GNa). The increase in GTot was antagonized by Ba2+, a nonselective K+ channel blocker, and abolished by clotrimazole, a KCNN4 inhibitor, but unaffected by other selective K+ channel blockers. Moreover, 1-ethyl-2-benzimidazolinone (1-EBIO), which is known to activate KCNN4, increased GK with no effect on GNa. RT-PCR-based analyses confirmed expression of mRNA encoding KCNN4 and suggested that two related K+ channels (KCNN1 and KCNMA1) were absent. Subsequent studies showed that 1-EBIO stimulates Na+ transport in polarized monolayers without affecting intracellular Ca2+ concentration ([Ca2+]i), suggesting that the activity of KCNN4 might influence the rate of Na+absorption by contributing to GK. Transient expression of KCNN4 cloned from H441 cells conferred a Ca2+- and 1-EBIO-sensitive K+ conductance on Chinese hamster ovary cells, but this channel was inactive when [Ca2+]i was <0.2 μM. Subsequent studies of amiloride-treated H441 cells showed that clotrimazole had no effect on Vm despite clear depolarizations in response to increased extracellular K+ concentration ([K+]o). These findings thus indicate that KCNN4 does not contribute to Vm in unstimulated cells. The present data thus establish that H441 cells express KCNN4 and highlight the importance of GK to the control of Na+ absorption, but, because KCNN4 is quiescent in resting cells, this channel cannot contribute to resting GK or influence basal Na+ absorption.",
author = "Wilson, {Stuart M.} and Brown, {Sean G.} and Niall McTavish and McNeill, {R. P.} and Husband, {E. M.} and Inglis, {Sarah K.} and Olver, {Richard E.} and Clunes, {M. T.}",
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Expression of intermediate-conductance, Ca2+-activated K+ channel (KCNN4) in H441 human distal airway epithelial cells. / Wilson, Stuart M.; Brown, Sean G.; McTavish, Niall; McNeill, R. P.; Husband, E. M.; Inglis, Sarah K.; Olver, Richard E.; Clunes, M. T.

In: American Journal of Physiology: Lung Celullar and Molecular Physiology, Vol. 291, No. 5, 09.06.2006, p. L957-L965.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Expression of intermediate-conductance, Ca2+-activated K+ channel (KCNN4) in H441 human distal airway epithelial cells

AU - Wilson,Stuart M.

AU - Brown,Sean G.

AU - McTavish,Niall

AU - McNeill,R. P.

AU - Husband,E. M.

AU - Inglis,Sarah K.

AU - Olver,Richard E.

AU - Clunes,M. T.

PY - 2006/6/9

Y1 - 2006/6/9

N2 - Electrophysiological studies of H441 human distal airway epithelial cells showed that thapsigargin caused a Ca2+-dependent increase in membrane conductance (GTot) and hyperpolarization of membrane potential (Vm). These effects reflected a rapid rise in cellular K+ conductance (GK) and a slow fall in amiloride-sensitive Na+ conductance (GNa). The increase in GTot was antagonized by Ba2+, a nonselective K+ channel blocker, and abolished by clotrimazole, a KCNN4 inhibitor, but unaffected by other selective K+ channel blockers. Moreover, 1-ethyl-2-benzimidazolinone (1-EBIO), which is known to activate KCNN4, increased GK with no effect on GNa. RT-PCR-based analyses confirmed expression of mRNA encoding KCNN4 and suggested that two related K+ channels (KCNN1 and KCNMA1) were absent. Subsequent studies showed that 1-EBIO stimulates Na+ transport in polarized monolayers without affecting intracellular Ca2+ concentration ([Ca2+]i), suggesting that the activity of KCNN4 might influence the rate of Na+absorption by contributing to GK. Transient expression of KCNN4 cloned from H441 cells conferred a Ca2+- and 1-EBIO-sensitive K+ conductance on Chinese hamster ovary cells, but this channel was inactive when [Ca2+]i was <0.2 μM. Subsequent studies of amiloride-treated H441 cells showed that clotrimazole had no effect on Vm despite clear depolarizations in response to increased extracellular K+ concentration ([K+]o). These findings thus indicate that KCNN4 does not contribute to Vm in unstimulated cells. The present data thus establish that H441 cells express KCNN4 and highlight the importance of GK to the control of Na+ absorption, but, because KCNN4 is quiescent in resting cells, this channel cannot contribute to resting GK or influence basal Na+ absorption.

AB - Electrophysiological studies of H441 human distal airway epithelial cells showed that thapsigargin caused a Ca2+-dependent increase in membrane conductance (GTot) and hyperpolarization of membrane potential (Vm). These effects reflected a rapid rise in cellular K+ conductance (GK) and a slow fall in amiloride-sensitive Na+ conductance (GNa). The increase in GTot was antagonized by Ba2+, a nonselective K+ channel blocker, and abolished by clotrimazole, a KCNN4 inhibitor, but unaffected by other selective K+ channel blockers. Moreover, 1-ethyl-2-benzimidazolinone (1-EBIO), which is known to activate KCNN4, increased GK with no effect on GNa. RT-PCR-based analyses confirmed expression of mRNA encoding KCNN4 and suggested that two related K+ channels (KCNN1 and KCNMA1) were absent. Subsequent studies showed that 1-EBIO stimulates Na+ transport in polarized monolayers without affecting intracellular Ca2+ concentration ([Ca2+]i), suggesting that the activity of KCNN4 might influence the rate of Na+absorption by contributing to GK. Transient expression of KCNN4 cloned from H441 cells conferred a Ca2+- and 1-EBIO-sensitive K+ conductance on Chinese hamster ovary cells, but this channel was inactive when [Ca2+]i was <0.2 μM. Subsequent studies of amiloride-treated H441 cells showed that clotrimazole had no effect on Vm despite clear depolarizations in response to increased extracellular K+ concentration ([K+]o). These findings thus indicate that KCNN4 does not contribute to Vm in unstimulated cells. The present data thus establish that H441 cells express KCNN4 and highlight the importance of GK to the control of Na+ absorption, but, because KCNN4 is quiescent in resting cells, this channel cannot contribute to resting GK or influence basal Na+ absorption.

U2 - doi:10.1152/ajplung.00065.2006

DO - doi:10.1152/ajplung.00065.2006

M3 - Article

VL - 291

SP - L957-L965

JO - American Journal of Physiology: Lung Celullar and Molecular Physiology

T2 - American Journal of Physiology: Lung Celullar and Molecular Physiology

JF - American Journal of Physiology: Lung Celullar and Molecular Physiology

SN - 1040-0605

IS - 5

ER -