The probability of block (1 − P_o), rates of association/dissociation (k_on/k_off), and the affinity (K_d) of TPeA in ryanodine-modified WT and substituted RyR2 channels. (A–D) Blocking parameters were determined at 60 mV in the presence of 100 µM TPeA. Data are plotted as mean values (±SEM; n = 5–8; *, P < 0.05; **, P < 0.01; ***, P < 0.001).