Localization of Na ⁺ Channel Isoforms at the Atrioventricular Junction and Atrioventricular Node in the Rat

Our findings provide molecular evidence of multiple electrophysiological cell types at the AV junction. Impaired AV conduction as a result of mutations in or loss of Na(V)1.5 must be the result of impaired conduction in the AVN inputs (inferior nodal extension and transitional zone) or output (bundle branches) rather than the AVN itself (open node and penetrating AV bundle).