Taurine-evoked chloride current and its potentiation by intracellular Ca2+ in immature rat hippocampal CA1 neurons.

Taurine is one of the most abundant free amino acids in the immature mammalian central nervous system. In the present study, whole-cell patch-clamp recordings were made to examine taurine-evoked currents ( I(Tau)) in acutely dissociated immature rat hippocampal CA1 neurons. Taurine at low concentrations (</=1 mM) activated glycine receptors while at high concentrations (>/=3 mM) activated both glycine and GABA(A) receptors. Moreover, elevation of intracellular Ca(2+) via non-NMDA receptor activation enhanced I(Tau) reversibly. The results indicate that taurine may act as a native ligand of glycine receptors and modulate neurotransmissions in the immature hippocampus, and under certain conditions it can also activate GABA(A) receptors. The potentiation of I(Tau) by intracellular Ca(2+) may contribute to the protection effect of taurine under some cell-damaging conditions.