Cell cycle-related changes in transient K+ current density in the GH3 pituitary cell line

Laboratoire de Neurophysiologie, Centre National de la Recherche Scientifique UMR 5543, Université de Bordeaux 2, 33076 Bordeaux Cedex, France Our aim was to determine whether the expression of K + currents is related to the cell cycle in the excitable GH3 pituitary cell line. K + currents were stud...

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Published in:American Journal of Physiology: Cell Physiology 2000-12, Vol.279 (6), p.C1819-C1828
Main Authors: Czarnecki, A, Vaur, S, Dufy-Barbe, L, Dufy, B, Bresson-Bepoldin, L
Format: Article
Language:English
Subjects:
4-Aminopyridine - pharmacology
Antimetabolites
Bromodeoxyuridine
Cell Division - physiology
Cell Line
Charybdotoxin - pharmacology
Kinetics
Membrane Potentials - drug effects
Membrane Potentials - physiology
Patch-Clamp Techniques
Pituitary Gland - cytology
Potassium - metabolism
Potassium Channels - metabolism
S Phase - physiology
Tetraethylammonium - pharmacology
Thymidine - pharmacokinetics
Tritium
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Summary:Laboratoire de Neurophysiologie, Centre National de la Recherche Scientifique UMR 5543, Université de Bordeaux 2, 33076 Bordeaux Cedex, France Our aim was to determine whether the expression of K + currents is related to the cell cycle in the excitable GH3 pituitary cell line. K + currents were studied by electrophysiology, and bromodeoxyuridine (BrdU) labeling was used to compare their expression in cells thereafter identified as being in the S or non-S phase of the cell cycle. We show that the peak density of the transient outward K + current ( I to ) was 33% lower in cells in S phase (BrdU+) than in cells in other phases of the cell cycle (BrdU ). The voltage-dependence of I to was not modified. However, of the two kinetic components of I to inactivation, the characteristics of the fast component differed significantly between BrdU+ and BrdU cells. Recovery from inactivation of I to showed biexponential and monoexponential function in BrdU and BrdU+ cells, respectively. This suggests that the molecular basis of this current varies during the cell cycle. We further demonstrated that 4-aminopyridine, which blocks I to , inhibited GH3 cell proliferation without altering the membrane potential. These data suggest that I to may play a role in GH3 cell proliferation processes. potassium current; excitable cells; cell growth
ISSN:0363-6143
1522-1563
DOI:10.1152/ajpcell.2000.279.6.c1819