Gating of the expressed Cav3.1 calcium channel.

Intramembrane charge movement originating from Cav3.1 (T-type) channel expressed in HEK 293 cells was investigated. Ion current was blocked by 1 mM La3+. Charge movement was detectable for depolarizations above approximately -70 mV and saturated above +60 mV. The voltage dependence of charge movement followed a single Boltzmann function with half-maximal activation voltage +12.9 mV and +12.3 mV and with slopes of 22.4 mV and 18.1 mV for the ON- and OFF-charge movement, respectively. Inactivation of I(Ca) by prolonged depolarization pulse did not immobilize intramembrane charge movement in the Cav3.1 channel.