Different Sensitivities to pH of ATP-Induced Currents at Four Cloned P2X
Receptors
RON STOOP, ANNMARIE SURPRENANT, AND R. ALAN NORTH
Geneva Biomedical Research Institute, Glaxo Wellcome Research and
Development, Plan-les-Ouates, 1228 Geneva, Switzerland
APStracts 4:0095N, 1997.
ABSTRACT
The effect of changing extracellular pH was studied on the currents induced by
adenosine 5Õ-triphosphate (ATP) or ab-methylene-ATP in HEK293 cells
transfected with different P2X receptor subunits. In cells expressing P2X1,
P2X3 or P2X4 receptors, the effect of ATP was decreased by acidification. In
cells expressing P2X2 receptors, acidification increased the ATP-induced
current; this effect was also seen in cells expressing heteromeric P2X2 and
P2X3 receptors. At P2X2 receptors, acidification caused a leftward shift in
the ATP concentration-responses curve, without change in maximum; the pKa for
this effect was 7.3. At P2X4 receptors, acidification caused a rightward shift
in the ATP concentration-responses curve, without change in the maximum; the
pKa for this effect was 6.8. The pH dependence of the action of ATP should be
taken into account in studies of synaptic transmission, and may provide a
further tool to assign molecular identity to P2X receptors expressed by brain
neurons.
Received 26 February 1997; accepted in final form 12 June 1997.
APS Manuscript Number J162-7.
Article publication pending J. Neurophysiol.
ISSN 1080-4757 Copyright 1997 The American Physiological Society.
Published in APStracts on 15 July 1997