Figure 4.

The blockade of T-type Ca²⁺ current (I_CaT) by mibefradil in mouse Leydig cells. Acutely dissociated mouse Leydig cells were bathed in a bath solution containing 2 mmol L⁻¹ CaCl₂, 5 mmol L⁻¹ 4-aminopyridine, 136 mmol L⁻¹ TEA-Cl, 1.1 mmol L⁻¹ MgCl₂, 25 mmol L⁻¹ HEPES and 22 mmol L⁻¹ glucose, pH 7.4, and held at −100 mV. A command pulse was applied to −30 mV for 40 msec. Representative I_CaT traces were generated in the presence or absence of 1.0 μmol L⁻¹ mibefradil. The capacitive transients were suppressed from the traces for the clarity.