Estrogen regulation of the transient outward K+ current involves estrogen receptor α in mouse heart

•The role of E2 in regulating ion channels involved in repolarization remains incompletely understood.•Reduction of E2 through ovariectomy led to a specific increase in the density of Ito.•The increase in Ito was attributable to a Kv4.2 and Kv4.3 protein upregulation.•Transcriptional and post-transcriptional mechanisms regulate Kv4.3 and Kv4.2 respectively.•ERα and ERβ knock-out mice revealed that ERα has repressive role in regulating Kv4.3 and Ito.