LeTx-induced activation of Kir and Kv channels is specifically blocked by Ba2+ and by 4-AP, respectively. A, Overlays of typical current recordings from MH-S cells in control cells and in cells treated with 100 ng/ml LeTx (LF and PA) recorded in the absence of channel blockers (upper panel), in the presence of 300 μM Ba2+ to block Kir channels (middle panel), and in the presence of 3 mM 4-AP to block Kv channels (lower panel). B, Mean Kir current densities (−95 mV) in the six experimental cell populations described above. C, Mean Kv current densities (+60 mV) in the same experimental cell populations. Each data set is expressed as mean ± SEM. All experiments were repeated with three to five independent cell populations with 5–30 cells per condition. ***p < 0.001.