Role of Potassium Currents on Cell Excitability in Cardiac Ventricular Myocytes

Potassium Currents and Cell Excitability. Ventricular cell excitability has been mostly associated with the ability of sodium currents to generate an action potential upstroke. However, even in the presence of normal sodium currents, a cell will not generate an active response if it is unable to depolarize from the resting potential to the activation threshold. This article summarizes recent data demonstrating that potassium currents can act as important modulators of cell excitability. In fact, potassium currents can play a major role in determining the dynamics of Wenckebach periodicity, hysteresis of excitability, and active facilitation in ventricular myocytes. The article discusses the specific roles that the inward rectifier, I_Kb the delayed rectifier, I_K, and the ATP-sensitive, I_K-ATP currents play on the dynamic modulation of cell excitation. (J Cardiovasc Electrophysiol, Vol. 3, pp. 474–486. October 1992)