Referenced in: none

Automatically associated channels: Kv7.1

Title: Impaired IKs channel activation by Ca(2+)-dependent PKC shows correlation with emotion/arousal-triggered events in LQT1.

Authors: Jin O-Uchi, J Jeremy Rice, Martin H Ruwald, Xiaorong Xu Parks, Elsa Ronzier, Arthur J Moss, Wojciech Zareba, Coeli M Lopes

Journal, date & volume: J. Mol. Cell. Cardiol., 2015 Feb , 79, 203-11

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/25479336

Abstract
The most common inherited cardiac arrhythmia, LQT1, is due to IKs potassium channel mutations and is linked to high risk of adrenergic-triggered cardiac events. We recently showed that although exercise-triggered events are very well treated by ß-blockers for these patients, acute arousal-triggered event rate were not significantly reduced after beta-blocker treatment, suggesting that the mechanisms underlying arousal-triggered arrhythmias may be different from those during exercise. IKs is strongly regulated by β-adrenergic receptor (β-AR) signaling, but little is known about the role of α1-AR-mediated regulation.Here we show, using a combination of cellular electrophysiology and computational modeling, that IKs phosphorylation and α1-AR regulation via activation of calcium-dependent PKC isoforms (cPKC) may be a key mechanism to control channel voltage-dependent activation and consequently action potential duration (APD) in response to adrenergic-stimulus. We show that simulated mutation-specific combined adrenergic effects (β+α) on APD were strongly correlated to acute stress-triggered cardiac event rate for patients while β-AR effects alone were not.We were able to show that calcium-dependent PKC signaling is key to normal QT shortening during acute arousal and when impaired, correlates with increased rate of sudden arousal-triggered cardiac events. Our study suggests that the acute α1-AR-cPKC regulation of IKs is important for QT shortening in "fight-or-flight" response and is linked to decreased risk of sudden emotion/arousal-triggered cardiac events in LQT1 patients.