Figure 4.

Effects of TTX and eleclazine on the reverse use dependence (RUD) of MAPD₉₀ caused by Bay K 8644. (a) Values of MAPD₉₀ were measured in the absence (Ctrl) and presence of Bay K 8644 (200 nM), Bay K 8644 (200 nM) plus TTX (n = 11). ^* P < 0.05 vs. cycle length (CL) of 400 ms; ^# P < 0.05 vs. Ctrl at the same CL; ^† P < 0.05 vs. Bay K 8644 alone at the same CL. (b) Representative AP traces obtained when hearts were paced at CLs of 400 ms, 1000 ms and 2000 ms in control, Bay K 8644 alone, Bay K 8644 plus TTX, and Bay K 8644 plus eleclazine. (c) and (d) Representative recordings of MAPs (upper records in each panel) and ECG (lower records in each panel) were recorded at pacing CL of 2000 ms in control, Bay K 8644 (200 nM), Bay K 8644 + TTX (1 µM), and Bay K 8644 + eleclazine (10 µM). Arrows indicate an episode of VT.