Effects of components of ischemia on the Kv4.3 current stably expressed in Chinese Hamster Ovary cells

Singarayar, S; Singleton, C; Tie, H; Wyse, K; Bursill, J; Bauskin, A; Wu, W; Valenzuela, S; Breit, S; Campbell, T

Effects of components of ischemia on the Kv4.3 current stably expressed in Chinese Hamster Ovary cells

Singarayar, S Singleton, C Tie, H Wyse, K Bursill, J Bauskin, A Wu, W Valenzuela, S

Breit, S Campbell, T

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Publication Type:: Journal Article
Citation:: Journal of Molecular and Cellular Cardiology, 2002, 34 (2), pp. 197 - 207
Issue Date:: 2002-02-01

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Field	Value	Language
dc.contributor.author	Singarayar, S	en_US
dc.contributor.author	Singleton, C	en_US
dc.contributor.author	Tie, H	en_US
dc.contributor.author	Wyse, K	en_US
dc.contributor.author	Bursill, J	en_US
dc.contributor.author	Bauskin, A	en_US
dc.contributor.author	Wu, W	en_US
dc.contributor.author	Valenzuela, S https://orcid.org/0000-0001-5934-6047	en_US
dc.contributor.author	Breit, S	en_US
dc.contributor.author	Campbell, T	en_US
dc.date.issued	2002-02-01	en_US
dc.identifier.citation	Journal of Molecular and Cellular Cardiology, 2002, 34 (2), pp. 197 - 207	en_US
dc.identifier.issn	0022-2828	en_US
dc.identifier.uri	http://hdl.handle.net/10453/9414
dc.description.abstract	We investigated the effects of three components of ischemia: external acidosis (pH = 6.0), extracellular hyperkalemia ([K+] = 20 mmol/l), and resting membrane depolarization to -60 mV. on Kv4.3 current stably expressed in Chinese Hamster Ovary cells. We used single electrode whole cell patch clamp techniques to study changes in the current elicited. External acidosis caused a positive shift in the steady state activation curve from -13.4±2.1 mV to -3.3±1.5 mV (n = 8, P = 0.004) and the steady state inactivation curve from -56.5±0.4 mV to -46.7±0.5 mV (n = 14, P<0.0001). Acidosis also caused an acceleration of recovery from inactivation with the t1/2 decreasing from 306 ms (95% CI 287-327 ms) to 194 ms (95% CI 182-207 ms), (n = 14, P<0.05). Hyperkalemia did not affect any of these parameters. Combined acidosis and hyperkalemia produced effects similar to those seen with acidosis. Changing the holding potential from -90 mV to -60 mV with test potentials of +5 and +85 mV decreased the peak currents by 34.1% and 32.4% respectively (n = 14). However, in the presence of external acidosis the decrease in peak currents induced by changing the holding potential was less marked. In acidotic bath the peak current at -60 mV was reduced by only 13.6% at a test potential of +5 mV and 12.3% at a test potential of +85 mV (n = 14). Taken together our data suggest that the membrane depolarization and changes in pH which occur under ischemic conditions would be accompanied by relative preservation of Kv4.3 currents and provide a molecular basis for the observation of preserved epicardial Ito and epicardial action potential duration (APD) shortening in ischemia. © 2002 Elsevier Science Ltd.	en_US
dc.relation.ispartof	Journal of Molecular and Cellular Cardiology	en_US
dc.relation.isbasedon	10.1006/jmcc.2001.1502	en_US
dc.subject.classification	Cardiovascular System & Hematology	en_US
dc.subject.mesh	CHO Cells	en_US
dc.subject.mesh	Animals	en_US
dc.subject.mesh	Myocardial Ischemia	en_US
dc.subject.mesh	Ischemia	en_US
dc.subject.mesh	Acidosis	en_US
dc.subject.mesh	Hyperkalemia	en_US
dc.subject.mesh	Potassium Channels	en_US
dc.subject.mesh	Potassium Channels, Voltage-Gated	en_US
dc.subject.mesh	Gene Transfer Techniques	en_US
dc.subject.mesh	Transfection	en_US
dc.subject.mesh	Membrane Potentials	en_US
dc.subject.mesh	Cricetinae	en_US
dc.subject.mesh	Shal Potassium Channels	en_US
dc.title	Effects of components of ischemia on the Kv4.3 current stably expressed in Chinese Hamster Ovary cells	en_US
dc.type	Journal Article
utslib.citation.volume	2	en_US
utslib.citation.volume	34	en_US
utslib.for	0304 Medicinal and Biomolecular Chemistry	en_US
utslib.for	0306 Physical Chemistry (incl. Structural)	en_US
utslib.for	1004 Medical Biotechnology	en_US
utslib.for	1102 Cardiorespiratory Medicine and Haematology	en_US
utslib.for	1116 Medical Physiology	en_US
pubs.embargo.period	Not known	en_US
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/Faculty of Science
pubs.organisational-group	/University of Technology Sydney/Faculty of Science/School of Life Sciences
pubs.organisational-group	/University of Technology Sydney/Strength - CHT - Health Technologies
pubs.organisational-group	/University of Technology Sydney/Strength - IBMD - Initiative for Biomedical Devices
utslib.copyright.status	closed_access
pubs.issue	2	en_US
pubs.publication-status	Published	en_US
pubs.volume	34	en_US

Abstract:

We investigated the effects of three components of ischemia: external acidosis (pH = 6.0), extracellular hyperkalemia ([K+] = 20 mmol/l), and resting membrane depolarization to -60 mV. on Kv4.3 current stably expressed in Chinese Hamster Ovary cells. We used single electrode whole cell patch clamp techniques to study changes in the current elicited. External acidosis caused a positive shift in the steady state activation curve from -13.4±2.1 mV to -3.3±1.5 mV (n = 8, P = 0.004) and the steady state inactivation curve from -56.5±0.4 mV to -46.7±0.5 mV (n = 14, P<0.0001). Acidosis also caused an acceleration of recovery from inactivation with the t1/2 decreasing from 306 ms (95% CI 287-327 ms) to 194 ms (95% CI 182-207 ms), (n = 14, P<0.05). Hyperkalemia did not affect any of these parameters. Combined acidosis and hyperkalemia produced effects similar to those seen with acidosis. Changing the holding potential from -90 mV to -60 mV with test potentials of +5 and +85 mV decreased the peak currents by 34.1% and 32.4% respectively (n = 14). However, in the presence of external acidosis the decrease in peak currents induced by changing the holding potential was less marked. In acidotic bath the peak current at -60 mV was reduced by only 13.6% at a test potential of +5 mV and 12.3% at a test potential of +85 mV (n = 14). Taken together our data suggest that the membrane depolarization and changes in pH which occur under ischemic conditions would be accompanied by relative preservation of Kv4.3 currents and provide a molecular basis for the observation of preserved epicardial Ito and epicardial action potential duration (APD) shortening in ischemia. © 2002 Elsevier Science Ltd.

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http://hdl.handle.net/10453/9414