Fig. 4.

Specific block of T-type Ca²⁺ channel currents by 3,5-dichloro-N-[1-(2,2-dimethyl-tetrahydro-pyran-4-ylmethyl)-4-fluoro-piperidin-4-ylmethyl]-benzamide (TTA-P2). Concentration-dependent inhibition of Ca²⁺ channel currents by TTA-P2 was monitored in whole cell recordings. A: Ca²⁺ currents were recorded in 10 mM external Ca²⁺ in response to voltage steps to −5 mV from a holding potential of −80 mV before superfusion of the cell with 1 μM TTA-P2. Numbers (1 and 2) on traces (left) correspond to those on plot of peak current amplitude (right). B: Ca²⁺ currents were recorded in 10 mM Ba²⁺ in response to voltage steps to −5 mV, applied from a holding potential of −80 mV, before and after superfusion of the cell with 2 μM TTA-P2. Traces were recorded in control saline and after steady-state block by TTA-P2. C: concentration-dependent inhibition of Ca_V3.2 currents by TTA-P2. Ca²⁺ currents were recorded in the presence of 10 mM Ca²⁺ or 10 mM Ba²⁺. Bars show percent block of Ca_V3.2 current activated by short (10-ms) or long (300-ms) test pulses at 30-s intervals from −80 mV to test potentials of −5 or 0 mV. Values are means ± SE for number of determinations shown in parentheses.