Jpn. J. Pharmacol. 70 (1), 81-84 (1996)

Fenamates Potentiate the alpha1-Adrenoceptor-Activated Nonselective Cation Channels in Rabbit Portal Vein Smooth Muscle

Kazunori Yamada, Yoshiki Waniishi, Ryuji Inoue (*) and Yushi Ito

Department of Pharmacology, Faculty of Medicine, Kyushu University, Fukuoka 812-82, Japan (*) To whom correspondence should be addressed.

Abstract: The agonistic action of fenamates on the alpha1-adrenoceptor-activated cationic current (Icat) in rabbit portal vein smooth muscle was investigated with the whole-cell patch clamp technique. At -50 mV, the fenamates (100-500 microM) increased Icat dose-dependently, up to several fold. This increase was not accompanied by changes in the reversal potential and strongly inhibited by 500 microM Cd2+ or 10 mM procaine. The enhancing effect of fenamates was also observed on the cationic current activated by intracellularly applied GTPgammaS. These results suggest that fenamates may be useful as a new class of activator for receptor-operated cation channels in smooth muscle.

Keywords: Cation channel opener, Smooth muscle, Fenamate

Copyright© The Japanese Pharmacological Society 1996

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