Down regulation of volume-activated cl- currents during muscle
differentiation.
Voets, Thomas, Lin Wei, Patrick De Smet, Willy Van Driessche, Jan
Eggermont, Guy Droogmans, and Bernd Nilius.
K.U. Leuven, Laboratorium voor Fysiologie, Campus Gasthuisberg, B
-3000 LEUVEN, Belgium
APStracts 3:0288C, 1996.
We have used the whole-cell configuration of the patch clamp technique
to investigate volume-activated Cl- currents in BC3H1 and C2C12
cells, two mouse muscle cell lines that can be switched from a
proliferating to a differentiated, muscle-like state. Reducing the
extracellular osmolality by 40% evoked large Cl- currents in
proliferating BC3H1 and C2C12 cells. These currents were outwardly
rectifying and had an anion permeability sequence I- > Br-
> Cl- >> gluconate. They were inhibited by more
than 50 % by flufenamic acid (500 [mu]M), niflumic acid (500[mu]M)
and NPPB (5-nitro-2-(3-phenylpropylamino)benzoic acid) (100 [mu]M),
but were relatively insensitive to tamoxifen (100 [mu]M). A reduction
of the serum concentration in the culture medium induced growth
arrest in both cell lines, and the cells started to differentiate
into spindle-shaped non-fusing muscle cells (BC3H1) or myotubes
(C2C12). This differentiation was accompanied by a drastic decrease
of the magnitude of the volume-activated Cl- currents. The close
correlation between volume-activated Cl- currents and cell
proliferation suggests that these currents may be involved in cell
proliferation.
Received 25 March 1996; accepted in final form 6 September 1996.
APS Manuscript Number C169-6.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 7 October 1996