Multiple voltage-gated sodium channel α subunits expressed in adult rat ventricular myocytes

Objective: To observe the expressions of voltage-gated sodium channel (NaCh) α subunits in adult rat ventricular myocytes. Methods: Single ventricular myocytes were isolated from adult rat heart. Expressions of various α subunits (Nav1.1, Nav1.2, Nav1.3, Nav1.5, Nav1.6 and Nav1.7) of NaCh in the ventricular myocytes were detected by immunocytochemistry staining. Sodium current was recorded by whole-cell patch clamp method. Results: The neuronal subunits Nav1.1, Nav1.6 and Nav1.7 as well as the cardiac subunit Nav1.5 of NaCh were expressed in adult rat ventricular myocytes. Nav1.1, Nav1.5 and Nav1.7 were distributed along the cell membrane of the ventricular myocytes and around the transverse tubule; Nav1.6 was labeled along the cell membrane by lengthways. All these subunits were not colocalized with Cx43 at the intercalated disc. Both transient sodium current (I_{Na, T}) and late sodium current (I_{Na, L}) were recorded from adult rat ventricular myocytes. Conclusion: Various neuronal subunits (Nav1.1, Nav1.6 and Nav1.7) as well as cardiac subunit (Nav1.5) of NaCh were expressed in adult rat ventricular myocytes, which is important for normal function of I_{Na, T} and I_{Na, L}.