Altered Repolarization Reserve in Failing Rabbit Ventricular Myocytes: Calcium and {beta}-Adrenergic Effects on Delayed- and Inward-Rectifier Potassium Currents [Original Articles]

Conclusions:
At baseline Ca2+-dependent upregulation of IKr and IKs in HF counterbalances the reduced IK1, maintaining repolarization reserve (especially at higher heart rates) in physiological conditions, unlike conditions of strong cytosolic Ca2+ buffering. However, under β-adrenergic stimulation, reduced IKs responsiveness severely limits integrated repolarizing K+ current and repolarization reserve in HF. This would increase arrhythmia propensity in HF, especially during adrenergic stress.

Source: Circulation: Arrhythmia and Electrophysiology - February 8, 2018 Category: Cardiology Authors: Hegyi, B., Bossuyt, J., Ginsburg, K. S., Mendoza, L. M., Talken, L., Ferrier, W. T., Pogwizd, S. M., Izu, L. T., Chen-Izu, Y., Bers, D. M. Tags: Electrophysiology, Ion Channels/Membrane Transport, Heart Failure Original Articles Source Type: research