Characterization of two distinct potassium currents and gap
junctional communication in cultured rat hepatic stellate cells.
Kashiwagi, Satoshi, Makoto Suematsu, Yoshiyuki Wakabayashi, Norifumi
Kawada, Masaaki Tachibana, Amane Koizumi, Masayasu Inoue, Yuzuru
Ishimura, Akimichi Kaneko.
Departments of Biochemistry and Physiology and Urology, School of
Medicine, Keio University, Tokyo 160, First Department of
Biochemistry and Third Department of Internal Medicine, Osaka City
University School of Medicine, Osaka 545, Japan
APStracts 3:0202G, 1996.
This study aimed to examine electrophysiological properties of
cultured rat hepatic stellate cells using the whole cell
configuration of patch-clamp technique. At least three different
current components were identified: First, when the membrane was
depolarized to voltages more positive than -40 mV, a transient
outward K+ current was evoked. Second, membrane hyperpolarization
below -60 mV evoked a sustained and inward rectifying K+ current. The
third component was a current flowing outward which was activated
when the cell was depolarized more positively than 0 mV. The channel
for this current allowed Na+, K+ and Cl- to pass nonspecifically,
suggesting the presence of hemi-gap junctional channel. Furthermore,
a laser photobleaching technique revealed the presence of gap
junctions between adjacent hepatic stellate cells. A voltage-gated
Ca2+ current which is known to occur in smooth muscle cells was
searched for, but was not detectable. These results suggest that
membrane potential of hepatic stellate cells is determined
specifically by the two distinct K+ channels and by an intercellular
mechanism involving gap junctional communication.
Received 11 July 1996; accepted in final form 16 September 1996.
APS Manuscript Number G279-6.
Article publication pending Am. J. Physiol. (Gastrointest. Liver
Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 7 October 1996