Riluzole blocks Trmp4 macroscopic currents. A,B: Macroscopic whole cell currents from COS-7 cells expressing Trpm4-EGFPN1, shown at low temporal resolution (A) and higher resolution (B) during repetitive ramp pulses from –120 to +100 mV, 800 ms duration, every 15 s; Trpm4 currents were activated by adding the calcium-ionophore, A23187 (20 μM) to the bath to raise intracellular calcium; subsequent addition of riluzole (100 μM) blocked the current activated by raising intracellular calcium. C: Semi-log plot of the percent inhibition (mean± SE) of Trpm4 current in COS-7 cells (filled circles), measured at –50 mV, observed in the presence of various concentrations of riluzole; 3–7 cells at each concentration; the data for COS-7 cells were fit to a standard logistic equation with an IC50,31.4 μM; also shown is the percent block of Sur1-regulated NCCa-ATP channel currents in bEnd.3 cells by riluzole (empty circles); 5 cells at each concentration. D: Macroscopic whole cell currents from a bEnd.3 cell induced to express Sur1-regulated NCCa-ATP channels; currents were activated by depleting ATP using sodium azide (1 mM) plus 2-deoxyglucose (10 mM); subsequent addition of riluzole (100 μM) blocked the current activated by ATP depletion.