Membrane currents evoked by histamine in rabbit basilar artery.
Kamouchi, Masahiro, Rika Ogata, Masatoshi Fujishima, Yushi Ito, and
Kenji Kitamura.
Second Department of Internal Medicine and Department of
Pharmacology, Faculty of Medicine, Kyushu University, Fukuoka 812,
Japan, Department of Pharmacology, Fukuoka Dental College, Fukuoka
81401, Japan
APStracts 3:0410H, 1996.
The membrane current evoked by histamine in isolated smooth muscle
cells from rabbit basilar artery was investigated using the
perforated-patch technique. When 10 M histamine was applied in the
bath at a holding potential of -60 mV, an inward current (79.255.8
pA) was transiently activated. An outward current was additionally
evoked by 10 M histamine when the membrane was held at -40 mV or less
negative potentials. The outward, but not inward current was
completely blocked by 100 nM Charybdotoxin. A higher concentration of
histamine (30 M) failed to produce the inward current (3.4 4.8 pA),
when Cl- concentration in the pipette was reduced. The apparent
reversal potential of the inward current induced by histamine in PSS,
in high TEA+ solution (bath) or in low Cl- solution (pipette) was
-6.3 4.4 mV, -7.5 4.9 mV or -45.8 8.5 mV, respectively. Niflumic acid
(100 M) reversibly blocked the inward current which was also blocked
by 10 M pyrilamine, but not by 10 M cimetidine. When histamine was
continuously applied in the bath, spontaneous transient inward
currents were generated. Removal of external Ca2+, or addition of 1 M
nicardipine or 2 mM caffeine reduced the amplitude of the histamine
-induced inward current. These results suggest that histamine induces
an inward current via H1 receptors at the resting membrane potential,
possibly due to activation of Cl- currents. The Cl- inward current
might be generated by elevation of intracellular Ca2+ via histamine
receptors. The inward current may also contribute to control of the
Ca2+ influx via a change in the membrane potential.
Received 30 May 1995; accepted in final form 5 September 1996.
APS Manuscript Number H499-5.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 7 October 1996