Fig. 4.

Effects of T-type Ca²⁺ channel blockers on low voltage-activated Ca²⁺ currents of ICC in the presence of nicardipine. A and B: T-type Ca²⁺ currents were recorded by voltage steps from −80 to +50 mV in control and Ni²⁺ (30 μM) in the presence of nicardipine (1 μM). C: I–V relationships for peak current in control (●) and Ni²⁺ (○). Ni²⁺ completely blocked low voltage-activated Ca²⁺ currents. D and E: T-type Ca²⁺ currents were recorded by voltage steps from −80 to +60 mV in control and mibefradil (1 μM) in the presence of nicardipine (1 μM). F: I–V relationships for peak current in control (●) and mibefradil (○). Mibefradil completely blocked low voltage-activated Ca²⁺ currents.