Inhibition of T-type calcium channels by NMP compounds. . (A) The histogram summarizes the inhibitory effects of 10 μM NMP compounds on three subtypes of recombinant T-type calcium channels expressed in tsA-201 cells. The number of cells that have been tested is indicated on the top of the bars. (B) Further characterization of compounds NMP-4, NMP-7 and NMP-144 on Cav3.2 channels. The IC50 values obtained from the fit to the dose response relation were 2.47 μM, 1.84 μM 5.59 μM, respectively, for Cav3.1, Cav3.2 and Cav3.3. Data represent the mean ± SEM from 3 - 8 cells of each concentration of compounds. (C) Representative traces from a single cell showing the inhibitory effects of NMP-144 on Cav3.2 with different concentrations and recovery upon washout.