Properties of [3H]taurine release from crude synaptosomal fractions of rat cerebral cortex

The release of previously accumulated ³H]taurine and ¹⁴C]GABA from crude synaptosomal (P₂) fractions isolated from rat cerebral cortex was studied using a superfusion system. The spontaneous efflux of ³H]taurine and ¹⁴C]GABA was stimulated by elevated concentrations of K⁺ (15–133 mM) in a concentration-dependent manner. This K⁺-stimulated release of ¹⁴C]GABA but not of ³H]taurine was enhanced in the presence of Ca²⁺. However, addition of 3 mM Ca²⁺ to the superfusion medium in the presence of the ionophore A 23187 resulted in a stimulation of the release of both ³H]taurine and ¹⁴C]GABA. These results are discussed in connection with the cellular localization of tourine in the central nervous system.