Effect of eliprodil on the APD (APD90) in the presence of IK1 block by BaCl2 (10 μM) in canine right ventricular papillary muscle. In (a), representative action potential traces are shown under control conditions (open circle) in the presence of 10 μM BaCl2 alone (triangle) and after application of 1 μM eliprodil in the presence of IK1 block (square) at 1 s stimulation cycle length, while (b) illustrates the APD90 as a function of the stimulation frequency under control conditions (open circles), in the presence of 10 μM BaCl2 alone (triangles) and after application of 1 μM eliprodil in the presence of IK1 block (squares) (mean±s.e.m., *P<0.05 vs control, †P<0.05 vs BaCl2).