Connexin43 and Connexin40 are chamber-specific determinants of myocardial conduction, with Cx43 being critical for ventricular conduction and Cx40 for atrial conduction.
These results indicate that Cx43 is a principal conductor of intercellular current in the ventricle because ventricular conduction is significantly slowed when Cx43 content is reduced by only 50%. In contrast, a similar reduction in Cx43 content in atrial muscle has no effect on atrial conduction, suggesting that Cx40 (which is expressed in atrial but not ventricular myocytes) is a major electrical coupling protein in atrial muscle. Thus, Cx43 and Cx40 may be chamber-specific determinants of myocardial conduction.
Thomas et al. (Tue,) studied this question.