The role of gap junctions in stretch-induced atrial fibrillation

Aims The aim of this study was to investigate the role of gap junctions in atrial fibrillation (AF) by analysing the effects of a gap junction enhancer and blocker on AF vulnerability and electrophysiological properties of isolated hearts. Methods and results The acute atrial stretch model of AF in the isolated rabbit heart was used. Sustained AF (SAF) was induced by a burst of high-frequency stimulation of the Bachmann’s bundle. The effective refractory period (ERP) wasmeasured, and the total conduction time (TCT) and the pattern of conduction of the anterior surface of the left atriumweremonitored by using anopticalmapping system.The effect of enhancing gap junction function by 100–1000 nMrotigaptide (ZP123) and block by 30 mM carbenoxolone on these parameters was measured. SAF inducibility was increased with an elevation of intra-atrial pressure. Enhanced gap junction conductance induced by treatment with 100–1000 nM rotigaptide reduced SAF inducibility, and the gap junction blocker carbenoxolone increased SAF inducibility. In the absence of gap junction enhan-cer or blocker, normal conduction was observed at 0 cmH2O.When intra-atrial pressurewas raised to 12 cmH2O, th