Cardioprotective actions of taurine against intracellular and extracellular calcium-induced effects.

The effects of taurine were modulated by the [Ca2+]i or/and [Ca2+]o levels, consistent with recent reports (10, 28, 31). Taurine may directly and indirectly regulate the [Ca2+]i level by modulating Ca2+ channels (dependent on [Ca2+]i/[Ca2+]o) and Na+ channel (via Na(+)-Ca2+ exchange). Thus, taurine antagonizes Ca2+ ([Ca2+]o or [Ca2+]i)-induced cardiac functions. The data for the effects of taurine on the ionic currents and action potentials (automaticity) are summarized in Tables 1 and 2. These results indicate that taurine exerts potent cardioprotective actions under the conditions induced by low Ca2+ level as well as by calcium overload. In conclusion, the effects of taurine are complex, there being a number of actions on cardiac muscle which may show the possible therapeutic use of this sulfur amino acid.