Fig. 6.

Similar voltage-dependent activation of T- and L-type currents. I–V relationships were obtained in whole cell recordings from AZF cells with external solutions containing 10 mM Ca²⁺ or 10 mM Ba²⁺. Currents were activated by 300-ms voltage steps applied at 30-s intervals to various test potentials from a holding potential of −80 mV. A: I–V relationship recorded in 10 mM Ca²⁺ for T-type current. B and C: I–V relationships recorded in 10 mM Ba²⁺ for slowly and rapidly activating L-type currents. Current amplitudes are averages of 100 (of 1,440) points near the end of a 300-ms test pulse. D: voltage dependence of T- and L-type currents in Ba²⁺ or Ca²⁺. Ca²⁺ and Ba²⁺ currents were activated as described above in 10 mM Ca²⁺ or 10 mM Ba²⁺. Normalized current amplitudes were averaged and plotted against test potentials for T-type currents in Ca²⁺, L-type currents in Ca²⁺, and L-type currents in Ba²⁺.