Simultaneous activation of the small conductance calcium activated potassium current by acetylcholine and inhibition of sodium current by ajmaline cause J-wave syndrome in Langendorff-perfused rabbit ventricles.

Abstract Background Concomitant apamin-sensitive small conductance, calcium activated potassium current (IKAS) activation and INa inhibition induce J-wave syndrome (JWS) in rabbit hearts. Sudden death in JWS occurs predominantly in men at night, when parasympathetic tone is strong. Objective To test the hypotheses that acetylcholine (ACh), the parasympathetic transmitter, activates IKAS and causes JWS in the presence of ajmaline. Methods We performed optical mapping in Langendorff-perfused rabbit hearts and whole-cell voltage clamp to determine IKAS in isolated ventricular cardiomyocytes. Results ACh (1 μM) + ajmaline (2 μM) induced J-point elevations in all (6 male and 6 female) hearts from 0.01± 0.01 to 0.31 ± 0.05 mV (p Conclusion ACh activates ventricular IKAS. ACh and ajmaline induce J-wave syndrome and facilitate the induction of ventricular arrhythmias more in male than female ventricles.