Figure 8.

The effects of CQ and AZM on canine AP in the presence of an intermediate concentration of ISO. The AP and Ca²⁺ transient of non-treated, CQ 5 μM, AZM 20 μM and combined groups with 1 Hz pacing and 1 nM ISO in the presence of low extracellular K⁺ ([K⁺]_o = 4.0 mM) were compared to [K⁺]_o = 5.4 mM. The dashed vertical lines indicate the end of AP in models with [K⁺]_o = 5.4 mM to provide a clearer depiction of the effects of reduced extracellular K⁺ on APD. AP, action potential; APD, action potential duration; Ctl, control; ISO, isoproterenol.