Weixin Liu1, Yoshihiko Sato1, Yoshisuke Hosoda1,
Koki Hirasawa1 and Hiroyuki Hanai2,*
1First Department of Medicine and 2Department of
Endoscopic and Photodynamic Medicine, Hamamatsu University School of Medicine,
3600 Hanada-cho, Hamamatsu, 431-3192, Japan
*Corresponding author.ﾊﾊFAX:+81-53-435-2852
E-mail: hanai@hama-med.ac.jp
Abstract: Effects of higenamine on Na+, K+
and Cl- transport were studied on stripped guinea pig distal
colonic mucosa in vitro using Ussing chambers. Addition of 10-5ﾊM
higenamine induced a biphasic change in short circuit current (Isc): a transient
increase followed by a long-lasting decrease that was accompanied by an
increase in transepithelial conductance (Gt). The initial phase with an
increase in Isc was partially inhibited by serosal bumetanide and abolished
by mucosal diphenylamine-2-carboxylate, a chloride channel blocker, indicating
transient induction of Cl- secretion. The second phase with a
decrease in Isc was composed of two effects: the inhibition of the amiloride-sensitive
electrogenic Na+ absorption and the stimulation of the bumetanide-sensitive
K+ secretion. However, the initial transient increase was not
observed at the lower concentration of higenamine (10-8-10-6ﾊM).
All the changes in Isc and Gt induced by higenamine were suppressed by the
non-selective b-adrenergic receptor antagonist
propranolol and by the b2-adrenergic
receptor antagonist ICI-118,551, but not by the b1-adrenergic-receptor-selective
antagonist atenolol or by the a-antagonists phentolamine,
prazosin and yohimbine. These results suggest that higenamine inhibits electrogenic
Na+ absorption and stimulates electrogenic K+ and
Cl- secretion through b2-adrenergic
receptors in guinea pig distal colon.
Keywords: Na+ absorption, K+ secretion, Cl-
secretion, Aconite, b-Adrenergic receptor
Copyrightｩ The Japanese Pharmacological Society 2000
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