Caffeine-induced chloride current in dissociated rat
hepatocytes.
Yamashita, Yoshoro, and Norio Akaike.
the Department of Physiology, Kyushu University Faculty of
Medicine, Fukuoka 812-82, Japan
APStracts 2:0303C, 1995.
Current responses to caffeine in single hepatocytes dissociated from
adult rat liver were investigated with the conventional whole-cell
patch recording configuration. Caffeine produced a sustained inward
current (ICaf) with increasing conductance at a holding potential of
-40 mV. The reversal potential of ICaf was close to the Cl-
equilibrium potential. ICaf was not affected by the internal
perfusion of BAPTA or Cs+, whereas the Ca2+-activated K+ outward
current elicited by A23187 was inhibited by intracellular BAPTA or
Cs+. An 1 mM 3-isobutyl-1-methylxanthine (IBMX) was about equipotent
to 1 mM caffeine in inducing the current. ICaf was not modulated both
by the external application of H-8, a cyclic nucleotide-dependent
protein kinase inhibitor, and by intracellular perfusion with GDP
-[beta]S or GTP-[gamma]S. It was concluded that caffeine induced an
increase in membrane Cl- conductance without utilizing the rise of
intracellular free-Ca2+ or cAMP and without mediating G-protein,
suggesting the possible existence of caffeine receptor.Cl- channel
complexes on liver plasma membrane.
Received 15 August 1994; accepted in final form 9 August 1995.
APS Manuscript Number C465-4.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 24 August 1995.