Effects of RTV and APV on ventricular action potentials and normalized APD50 and APD90. (A,B) RTV (15 μM, 15 min; n = 4) significantly decreased APD50 and APD90, and abbreviation of APD was reversed by DCPIB (10 μM, 10 min). *, P < 0.05 vs Ctrl; †, vs 15 min RTV; ns, vs Ctrl. (C,D) APV (15 μM, 15 min; n = 3) did not significantly alter APD; ns, vs Ctrl.