Ca2+-permeable large-conductance nonselective cation channels in
rat basophilic leukemia cells.
Obukhov, A. G., S. V. P. Jones, V. E. Degtiar, A. L[umlaut]uckhoff, G.
Schultz, and J. Hescheler.
Institut f[umlaut]ur Pharmakologie, Freie Universit[umlaut]at
Berlin, Thielallee 69-73, D-14195 Berlin, F.R.G., Molecular
Neuropharmacology Section, Department of Psychiatry, University of
Vermont, Burlington, VT 05405, USA, present address: Institut
f[umlaut]ur Neurophysiologie, Universit[umlaut]at K[diaeresis]oln,
Robert-Koch-Str. 39, 50931 K[diaeresis]oln, F.R.G., Tel.: +49-30-838
-6687, Fax: +49-30-831-5954
APStracts 2:0196C, 1995.
Spreading of calcium signals in rat basophilic leukemia (RBL) cells
occurs by release of ATP. Therefore, we studied the effect of ATP on
membrane currents. ATP (1 to 10 M) activated large-conductance
channels. Single channel events were resolved in whole-cell mode.
Similar channel activity was observed in RBL cells transfected with
the muscarinic m1 receptor after stimulation with carbachol, as well
as after intracellular infusion of aluminum fluoride. Activation was
independent of internal Ca2+ (0 to 10 M). The channels had a
conductance of 250 pS in 135 mM Na+ and of 70 pS in 100 mM Ca2+. The
permeability ratios for various cations were PCa : PNa : PCs : PMg =
16 : 1 : 0.6 : 0.6. These channels may contribute to secretory
responses by allowing Ca2+ entry, leading to high Ca2+ concentrations
in the vicinity of the channel pore.
Received 10 January 1994; accepted in final form 28 April 1995.
APS Manuscript Number C14-4.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 16 May 1995.