Fig. 1.

Prolonged action potential (AP) durations (APDs) in adenylyl cyclase type 5 transgenic (AC5Tg) myocytes. A: representative AP recordings from ventricular myocytes of wild-type (WT) and AC5Tg mice. B: summary of APD at 50% repolarization (APD₅₀) and APD at 90% repolarization (APD₉₀) values. *P < 0.05 compared with WT control myocytes. Cell number is indicated above each bar (from 3–5 mice each). C: effect of Na⁺-free, Li⁺-containing Tyrode's solution on the AP properties in AC5Tg, suggesting the contribution of Ca²⁺ overload and Na⁺/Ca²⁺ exchange current (I_NCX) on the prolonged APD and early afterdepolarizations (EADs).