The Kv11.1 (also ERG1) K+ channel underlies cardiac I Kr, a current that contributes to repolarization in mammalian heart. In mice, IKr current density decreases with development and studies suggest that changes in the structure and/or properties of the heteromultimeric IKr/Kv11.1 channel are responsible. Here, using immunohistochemistry, we report that total Kv11.1 α subunit protein is more abundant in neonatal heart and is distributed throughout both adult and neonatal ventricles with greater abundance in epicardia. Immunoblots reveal that the α subunit alternative splice variant, Kv11.1a, is more abundant in adult heart while the Kv11.1b variant is more abundant in neonatal heart. Additionally, MinK channel subunit protein is shown to co-assemble with Kv11.1 protein and is more abundant in neonatal heart. In summary, Kv11.1/IKr channel composition varies developmentally and the higher IKr current density in neonatal heart is likely attributable to higher abundance of Kv11.1/IKr channels, more specifically, the Kv11.1b splice variant.
All Science Journal Classification (ASJC) codes
- Developmental Biology
- Cardiac ion channel
- MinK channel
- Potassium channel