Concentration-dependence of the effect of BaCl2 on AP amplitude and Vmax.
Concentration-dependence of the effect of BaCl2 to reduce AP amplitude, Vmax and MDP in two population of beating clusters (BC). 100 µM BaCl2 induced no changes in MDP in 13 out of 22 BC suggesting a small contribution or lack of IK1 (A, C and E), but led to membrane depolarization in 9 out of 22 BC (B, D and F). At concentrations at which BaCl2 also blocks IKr (500 µM), AP amplitude and Vmax decreased in both groups of BC. a: p<0.05 vs. Control; c: p<0.001 vs. Control.