Cell cycle-related changes in transient K(+) current density in the GH3 pituitary cell line.
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.
Czarnecki
A
A
Laboratoire de Neurophysiologie, Centre National de la Recherche Scientifique UMR 5543, Université de Bordeaux 2, 33076 Bordeaux Cedex, France.
Vaur
S
S
Dufy-Barbe
L
L
Dufy
B
B
Bresson-Bepoldin
L
L
D015761:4-Aminopyridine / Q000494:pharmacology; D000963:Antimetabolites; D001973:Bromodeoxyuridine; D002455:Cell Division / Q000502:physiology; D002460:Cell Line; D018999:Charybdotoxin / Q000494:pharmacology; D007700:Kinetics; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D018408:Patch-Clamp Techniques; D010902:Pituitary Gland / Q000166:cytology*; D011188:Potassium / Q000378:metabolism*; D015221:Potassium Channels / Q000378:metabolism*; D016196:S Phase / Q000502:physiology*; D019789:Tetraethylammonium / Q000494:pharmacology; D013936:Thymidine / Q000493:pharmacokinetics; D014316:Tritium
D000963:Antimetabolites; D015221:Potassium Channels; D014316:Tritium; D018999:Charybdotoxin; D019789:Tetraethylammonium; D015761:4-Aminopyridine; D001973:Bromodeoxyuridine; D011188:Potassium; D013936:Thymidine