Protective effect of taurine against decline of cardiac slow action potentials during hypoxia.

The effect of taurine on cardiac slow action potentials (APs) during hypoxic superfusion was studied in isolated guinea-pig papillary muscles. Ca2+-dependent slow APs were induced by isoproterenol (10(-6) M) in preparations which were voltage-inactivated by high (25 mM) K+. Although taurine had no effect on the slow AP parameters during normoxia, taurine (10 mM) superfusion significantly protected against the decline of slow APs produced by hypoxia. Taurine also restored slow APs that had been previously abolished by hypoxia. Therefore, taurine exposure may protect the Ca2+ slow channels which are inhibited or blocked by hypoxic conditions.