Regulation of gap junction conductance by calcineurin through Cx43 phosphorylation: implications for action potential conduction.

Cardiac arrhythmias are associated with raised intracellular [Ca] and slowed action potential conduction caused by reduced gap junction (GJ) electrical conductance (Gj). Ventricular GJs are composed of connexin proteins (Cx43), with Gj determined by Cx43 phosphorylation status. Connexin phosphorylation is an interplay between protein kinases and phosphatases but the precise pathways are unknown.

Aging is a primary risk factor for cardiac arrhythmias: disruption of intracellular Ca2+ regulation as a key suspect.

Aging is an inevitable time-dependent progression associated with a functional decline of the cardiovascular system even in 'healthy' individuals. Age positively correlates with an increasing risk of cardiac problems including arrhythmias. Not only the prevalence but also the severity of arrhythmias escalates with age.