Identification of Ether à Go-Go and Calcium-Activated Potassium Channels in Human Melanoma Cells

Identification of Ether à Go-Go and Calcium-Activated Potassium Channels in Human Melanoma Cells Ion channels and intracellular Ca2+ are thought to be involved in cell proliferation and may play a role in tumor development. We therefore characterized Ca2+-regulated potassium channels in the human melanoma cell lines IGR1, IPC298, and IGR39 using electrophysiological and molecular biological methods. All cell lines expressed outwardly rectifying K+ channels. Rapidly activating delayed rectifier channels were detected in IGR39 cells. The activation kinetics of voltage-gated K+ channels in IRG1 and IPC298 cells displayed characteristics of ether à go-go (eag) channels as they were much slower and depended both on the holding potential and on extracellular Mg2+. In addition, they could be blocked by physiological concentrations of intracellular Ca2+. In accordance with these electrophysiological results, analysis of mRNA revealed the expression of a gene coding for h-eag1 channels in IGR1 and IPC298 cells, but not in IGR39 cells. At elevated Ca2+ concentrations various types of Ca2+-activated K+ channels with single-channel characteristics similar to IK and SK channels were detected in IGR1 cells. The whole-cell Ca2+-activated K+ currents were not voltage dependent, insensitive for 100 nm apamin and 200 μm d-tubocurarine, but were blocked by charybdotoxin (100 nm) and clotrimazole (50 nm). Analysis of mRNA revealed the expression of hSK1, hSK2, and hIK channels in IGR1 cells. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Journal of Membrane Biology Springer Journals

Identification of Ether à Go-Go and Calcium-Activated Potassium Channels in Human Melanoma Cells

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Publisher
Springer-Verlag
Copyright
Copyright © Inc. by 1999 Springer-Verlag New York
Subject
Life Sciences; Biochemistry, general; Human Physiology
ISSN
0022-2631
eISSN
1432-1424
D.O.I.
10.1007/s002329900563
Publisher site
See Article on Publisher Site

Abstract

Ion channels and intracellular Ca2+ are thought to be involved in cell proliferation and may play a role in tumor development. We therefore characterized Ca2+-regulated potassium channels in the human melanoma cell lines IGR1, IPC298, and IGR39 using electrophysiological and molecular biological methods. All cell lines expressed outwardly rectifying K+ channels. Rapidly activating delayed rectifier channels were detected in IGR39 cells. The activation kinetics of voltage-gated K+ channels in IRG1 and IPC298 cells displayed characteristics of ether à go-go (eag) channels as they were much slower and depended both on the holding potential and on extracellular Mg2+. In addition, they could be blocked by physiological concentrations of intracellular Ca2+. In accordance with these electrophysiological results, analysis of mRNA revealed the expression of a gene coding for h-eag1 channels in IGR1 and IPC298 cells, but not in IGR39 cells. At elevated Ca2+ concentrations various types of Ca2+-activated K+ channels with single-channel characteristics similar to IK and SK channels were detected in IGR1 cells. The whole-cell Ca2+-activated K+ currents were not voltage dependent, insensitive for 100 nm apamin and 200 μm d-tubocurarine, but were blocked by charybdotoxin (100 nm) and clotrimazole (50 nm). Analysis of mRNA revealed the expression of hSK1, hSK2, and hIK channels in IGR1 cells.

Journal

The Journal of Membrane BiologySpringer Journals

Published: Sep 15, 1999

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