The effects of Tl+ ions on the dynamics of intracellular Ca2+ in rat cardiomyocytes

Resumo

The effects of Т1⁺ ions on the dynamics of intracellular Cа²⁺ in neonatal rat cardiomyocytes have been studied. It was shown for the first time that application of Т1⁺ led to an uncontrolled increase in [Cа²⁺]_i in cells. Moreover, the ability of Т1⁺ to increase [Cа²⁺]_i depended on the Т1⁺ concentration used and the time of exposure to the cells. The increase in [Cа²⁺]_i was related to the entry of Cа²⁺ from the extracellular medium. Thallium did not release Cа²⁺ from intracellular stores. The thallium-induced increase in [Cа²⁺]_i was not inhibited by nifedipine. It is possible that L-channels do not participate in the processes of thalliuminduced increase in [Cа²⁺]_i. It is assumed that the thallium ions-induced calcium overload in cardiomyocytes may contribute to the toxic effect of Т1⁺ on the myocardium.