Ca²⁺ Depletion Facilitates Taurine Release in Cultured Rat Astrocytes

Abstract

Removal of external Ca²⁺ facilitated endogenous taurine release in cultured rat astrocyies. 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 astrocyies. 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.