Representative waveforms of superimposed APs recorded before and after exposure to TTX and then ACO (a) or MACO (b) in the presence of TTX. Quantitative data for AP parameter measurements in the presence of TTX: c Effects of ACO on APD30, APD50 and APD90; d Effects of ACO on APA and RMP; e Effects of MACO on APD30, APD50, and APD90; f Effects of MACO on APA and RMP. There were seven cells from three guinea pig hearts per group. *P < 0.05, vs. control group; #P < 0.05, ##P < 0.01 vs. TTX group.