title: Cx43 and dual-pathway electrophysiology of the atrioventricular node and atrioventricular nodal reentry.
abstract: Fluorescent imaging has revealed that posterior nodal extensions provide the anatomical substrate for the dual-pathway electrophysiology of the atrioventricular (AV) node during normal conduction and reentry. The reentry can be intranodal, or as well as the posterior nodal extensions, it can involve an endocardial layer of atrial/atrial-nodal (A/AN) cells as part of the AV nodal reentry (AVNR) circuit. Using fluorescent imaging with a voltage-sensitive dye and immunolabeling of Cx43, we mapped the electrical activity and structural substrate in 3 types of AVNR induced by premature atrial stimulation in 8 rabbit hearts. In 6 cases, the AVNR pathway involved (1) a fast pathway (FP), (2) the A/AN layer, and (3) a slow pathway (SP). In 4 cases, reentry took the path (1) SP, (2) A/AN layer, and (3) FP. In 2 cases, reentry was intranodal, propagating between the 2 posterior nodal extensions. Immunolabeling revealed that the FP and SP are formed by Cx43-expressing bundles surrounded by tissue without Cx43. Cx43-expressing posterior nodal extensions are the substrate of AVNR during both intranodal and extranodal reentry.
authors.affiliation: Dept of Biomedical Engineering, Case Western Reserve University, 10900 Euclid Ave, Cleveland, Ohio 44106-7207, USA.
authors.forename: Vladimir P
authors.initials: VP
authors.lastname: Nikolski
authors.forename: Sandra A
authors.initials: SA
authors.lastname: Jones
authors.forename: Matthew K
authors.initials: MK
authors.lastname: Lancaster
authors.forename: Mark R
authors.initials: MR
authors.lastname: Boyett
authors.forename: Igor R
authors.initials: IR
authors.lastname: Efimov
mesh_terms: D000818:Animals; D001283:Atrioventricular Node / Q000737:chemistry / Q000502:physiology*; D018031:Connexin 43 / Q000032:analysis / Q000502:physiology*; D004594:Electrophysiology; D006329:Heart Conduction System / Q000502:physiology / Q000503:physiopathology; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D011817:Rabbits; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000503:physiopathology*
chemical_list: D018031:Connexin 43