Kazuhiro Takuma (1,#), Toshio Matsuda (1), Yoko Kishida (1), Shoichi Asano (1), Junichi Azuma (2) and Akemichi Baba (1,*)
(1) Department of Pharmacology and (2) Department of Clinical Evaluation of Medicine and Therapeutics, Faculty of Pharmaceutical Sciences, Osaka University, 1-6 Yamada-oka, Suita, Osaka 565, Japan (#) Present address: Department of Analytical Chemistry, Faculty of Pharmaceutical Sciences, Kobe Gakuin University, Nisi-ku, Kobe 651-21, Japan (*) To whom correspondence should be addressed.
Abstract: Removal of external Ca2+ facilitated endogenous taurine release in cultured rat astrocytes. The stimulated release was not affected by furosemide, sucrose, tetrodotoxin and 3,4-dichlorobenzamil, but partially inhibited by nifedipine. Omission of external Na+ increased basal taurine release, and the effects of Na+ removal and Ca2+ depletion on the release were additive. The Na+-free condition did not affect Ca2+ paradox-induced cell death in astrocytes. These findings suggest that Ca2+ depletion facilitates taurine release in a mechanism independent of volume and the Na+ gradient and that the release is not involved in Ca2+ paradox-induced delayed cell toxicity in astrocytes.
Taurine release, Ca2+ paradox, Astrocyte
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