Tonic block of mouse neuronal or human Cav3.X [T-type] calcium channels induced by either 1 μM application of ProTx I or 1 μM application of ProTx II. For recordings from native channels, ProTx I was tested on mouse thalamic neurons, ProTx II was tested on mouse DRG neurons, which respectively, expressed Cav3.1 and Cav3.2 channels. Shown are representative current traces from these experiments showing similar ProTx I block of native thalamic mouse T-type currents (first trace) and recombinant human Cav3.1 (second trace), and similar ProTx II block of mouse DRG T-type current (third trace) and recombinant human Cav3.2 (fourth trace) (control traces are depicted in black). Error bars reflect standard errors, asterisks denote statistical significance relative to either hCav3.1 [ProTx I] or hCav3.2 [ProTx II] [*p < 0.05, **p < 0.01]. Currents were elicited by stepping from a holding potential of −110 mV to a test potential of −20 mV.