Characterization of the Rapidly Activating Delayed Rectifier Potassium Current, I Kr, in HL-1 Mouse Atrial Myocytes

Characterization of the Rapidly Activating Delayed Rectifier Potassium Current, I Kr, in HL-1... HL-1 is the adult murine cardiac cell line that can be passaged repeatedly in vitro without losing differentiated phenotype. The present study was designed to characterize the rapidly activating delayed rectifier potassium current, I Kr, endogenously expressed in HL-1 cells using the whole-cell patch-clamp technique. In the presence of nisoldipine, depolarizing voltage steps applied from a holding potential of −50 mV evoked the time-dependent outward current, followed by slowly decaying outward tail current upon return to the holding potential. The amplitude of the current increased with depolarizations up to 0 mV but then progressively decreased with further depolarizations. The time-dependent outward current as well as the tail current were highly sensitive to block by E-4031 and dofetilide (IC50 of 21.1 and 15.1 nM, respectively) and almost totally abolished by micromolar concentrations of each drug, suggesting that most of the outward current in HL-1 cells was attributable to I Kr. The magnitude of I Kr available from HL-1 cells (18.1 ± 1.5 pA pF−1) was sufficient for reliable measurements of various gating parameters. RT-PCR and Western blot analysis revealed the expression of alternatively spliced forms of mouse ether-a-go-go-related genes (mERG1), the full-length mERG1a and the N-terminally truncated mERG1b isoforms. Knockdown of mERG1 transcripts with small interfering RNA (siRNA) dramatically reduced I Kr amplitude, confirming the molecular link of mERG1 and I Kr in HL-1 cells. These findings demonstrate that HL-1 cells possess I Kr with properties comparable to those in native cardiac I Kr and provide an experimental model suitable for studies of I Kr channels. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Journal of Membrane Biology Springer Journals

Characterization of the Rapidly Activating Delayed Rectifier Potassium Current, I Kr, in HL-1 Mouse Atrial Myocytes

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Publisher
Springer-Verlag
Copyright
Copyright © 2010 by Springer Science+Business Media, LLC
Subject
Life Sciences; Human Physiology ; Biochemistry, general
ISSN
0022-2631
eISSN
1432-1424
D.O.I.
10.1007/s00232-010-9257-2
Publisher site
See Article on Publisher Site

Abstract

HL-1 is the adult murine cardiac cell line that can be passaged repeatedly in vitro without losing differentiated phenotype. The present study was designed to characterize the rapidly activating delayed rectifier potassium current, I Kr, endogenously expressed in HL-1 cells using the whole-cell patch-clamp technique. In the presence of nisoldipine, depolarizing voltage steps applied from a holding potential of −50 mV evoked the time-dependent outward current, followed by slowly decaying outward tail current upon return to the holding potential. The amplitude of the current increased with depolarizations up to 0 mV but then progressively decreased with further depolarizations. The time-dependent outward current as well as the tail current were highly sensitive to block by E-4031 and dofetilide (IC50 of 21.1 and 15.1 nM, respectively) and almost totally abolished by micromolar concentrations of each drug, suggesting that most of the outward current in HL-1 cells was attributable to I Kr. The magnitude of I Kr available from HL-1 cells (18.1 ± 1.5 pA pF−1) was sufficient for reliable measurements of various gating parameters. RT-PCR and Western blot analysis revealed the expression of alternatively spliced forms of mouse ether-a-go-go-related genes (mERG1), the full-length mERG1a and the N-terminally truncated mERG1b isoforms. Knockdown of mERG1 transcripts with small interfering RNA (siRNA) dramatically reduced I Kr amplitude, confirming the molecular link of mERG1 and I Kr in HL-1 cells. These findings demonstrate that HL-1 cells possess I Kr with properties comparable to those in native cardiac I Kr and provide an experimental model suitable for studies of I Kr channels.

Journal

The Journal of Membrane BiologySpringer Journals

Published: May 19, 2010

References

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