Connexin40 Imparts Conduction Heterogeneity to Atrial Tissue

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Abstract
Impulse propagation in cardiac tissue is a complex process in which intercellular coupling through gap junction channels is a critical component. Connexin40 (Cx40) is an abundant gap junction protein that is expressed in atrial myocytes. Alterations in the expression of Cx40 have been implicated in atrial arrhythmogenesis. The purpose of the current study was to assess the role of Cx40 in atrial impulse propagation. High-resolution optical mapping was used to study conduction in the right and left atrial appendages of isolated Langendorff-perfused murine hearts. Wild-type (Cx40+/+), heterozygous (Cx40+/−), and knockout (Cx40−/−) mice, both adult and embryonic, were studied to assess the effects of reduced Cx40 expression on sinus node function and conduction velocity at different pacing cycle lengths (100 and 60 ms). In both adult and late-stage embryonic Cx40+/+ mice, heterogeneity in CV was found between the right and left atrial appendages. Either partial (Cx40+/−) or complete (Cx40−/−) deletion of Cx4...