CA2+ DEPLETION FACILITATES TAURINE RELEASE IN CULTURED RAT ASTROCYTES

Removal of external Ca2+ facilitated endogenous taurine release in cul tured rat astrocytes. The stimulated release was not affected by furos emide, sucrose, tetrodotoxin and 3,4-dichlorobenzamil but partially in hibited by nifedipine. Omission of external Na+ increased basal taurin e release, and the effects of Na+ removal and Ca2+ depletion on the re lease were additive. The Na+-free condition did not affect Ca2+ parado x-induced cell death in astrocytes. These findings suggest that Ca2+ d epletion facilitates taurine release in a mechanism independent of vol ume and the Na+ gradient and that the release is not involved in Ca2paradox-induced delayed cell toxicity in astrocytes.