Taurine regulates mitochondrial calcium homeostasis.

We have investigated the protective role of taurine in glutamate-mediated cell death and the involvement of mitochondria in this process. In cultured cerebellar granule cells, glutamate induces a rapid and sustained elevation in cytoplasmic free calcium ([Ca2+]i), causing the collapse of the mitochondrial electrochemical gradient (MtECG) and subsequent cell death. We found that pre-treatment with taurine, did not affect the level of calcium uptake with glutamate but rather reduced its duration; the calcium increase was transient and returned to basal levels about 10 min after adding glutamate. Furthermore, taurine reduced mitochondrial calcium concentration under non-depolarizing conditions. Treatment of cerebellar granule cells with taurine enhanced mitochondrial activity as measured by rhodamine uptake, both in the presence or absence of glutamate. We conclude that taurine prevents or reduces glutamate excitotoxicity through both the enhancement of mitochondrial function and the regulation of intracellular (cytoplasmic and mitochondrial) calcium homeostasis.