Probable Ca2+-mediated inactivation of Ca2+ currents in mammalian brain neurons.

In rat hippocampal neurons, current- and single-electrode voltage-clamp analyses revealed a pronounced inactivation of probable Ca2+ currents (ICa), which was dependent on the amount of Ca2+ influx. Studies were conducted in cesium-loaded, tetrodotoxin-treated brain slice neurons in which known contaminating currents were blocked. These results therefore provide the first clear evidence that apparent Ca2+-mediated inactivation of ICa is an important mechanism with which mammalian brain neurons limit Ca2+ influx.