Open AccessInhibitory Effects of Bifemelane on Brain Ca2+ Channel Subtypes Expressed in Xenopus Oocytes
Author(s) -
Mariko Kinoshita,
Shuji Kaneko,
Tohru Yasuno,
Nobumichi Yada,
Akinori Akaike,
Masamichi Satoh
Publication year - 1998
Publication title -
japanese journal of pharmacology/japanese journal of pharmacology
Language(s) - English
Resource type - Journals
eISSN - 1347-3506
pISSN - 0021-5198
DOI - 10.1254/jjp.78.39
Subject(s) - xenopus , inhibitory postsynaptic potential , neuroscience , chemistry , microbiology and biotechnology , biology , biophysics , biochemistry , gene
Effects of the cerebroprotective agent bifemelane on voltage-dependent Ca2+ channel currents were evaluated in Xenopus oocytes expressing specific Ca2+-channel subtypes. Extracellular perfusion of bifemelane showed a dose-dependent blocking action on both N-type and Q-type Ca2+ channels, but not on cardiac L-type Ca2+ channels expressed in the oocytes, and the inhibitory action on Q-type current was stronger than that on N-type current. The time course of inhibition by bifemelane was comparatively slow; a 20-min perfusion with 1 microM bifemelane was required to reduce the amplitude of the Q-type current to 80% of the control level. When bifemelane was applied intracellularly, the potency and time-course of inhibition was equivalent to that caused by the perfusion of bifemelane. The bifemelane-induced inhibition was voltage-dependent but not use-dependent in Q-type channels since it was apparent at more depolarized potentials but not influenced by the interval of depolarization. These results suggest that bifemelane inhibits the opening of the specific Ca2+ channels located at nerve terminals to suppress excessive neurotransmitter release from neurons in some pathophysiological conditions such as ischemia.