Article

Changes in the K+ current-density of MCF-7 cells during progression through the cell cycle: possible involvement of a h-ether.a-gogo K+ channel.

Laboratoire de Physiologie Cellulaire, INSERM, France.
Receptors and Channels 02/2001; 7(5):345-56.
Source: PubMed

ABSTRACT MCF-7 cells express voltage-activated K+ channels. In the present study, we used the patch-clamp and RT-PCR techniques to investigate the involvement of these channels during the cell cycle progression. The outward rectifier current (IK) recorded during depolarization was almost completely suppressed by the classical K+ channel blocker tetraethylammonium (TEA) in MCF-7 cells. TEA also inhibited cell proliferation, as measured with 3H-thymidine incorporation. Moreover, profound changes were observed in both the resting membrane potential (RMP) and IK during the release from the G0/G1 phase of the cell cycle. MCF-7 cells arrested in G0/G1 were depolarized (-26.3 +/- 10 mV, n = 30) and IK-density was small (9.4 +/- 5.6 pA/pF, n = 60) compared to cells progressing in the G1 phase (RMP = -60 +/- 7.9 mV; n = 35 and IK-density = 30.2 +/- 8.5 pA/pF; n = 76). IK was highly sensitive to Mg2+, astemizole and TEA (10 mM). Extracellular perfusion of 5 mM Mg2+ dramatically slowed the activation and perfusion of 2 microM astemizole inhibited both IK (20 +/- 3%) and cell proliferation (23%). Moreover, the h-EAG mRNA expression was modulated during the cell cycle. Thus, these data suggested that h-EAG K+ channels play a role in controlling the proliferation and/or cell cycle.

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Keywords

3H-thymidine incorporation
 
activation
 
cell cycle
 
cell cycle progression
 
cell proliferation
 
channels
 
classical K+ channel blocker tetraethylammonium
 
depolarization
 
Extracellular perfusion
 
G1 phase
 
h-EAG K+ channels
 
h-EAG mRNA expression
 
MCF-7 cells
 
outward rectifier current
 
patch-clamp
 
profound changes
 
resting membrane potential
 
RMP
 
RT-PCR techniques
 
voltage-activated K+ channels