Cardiac action potential phases - ion currents
Core concept
| Phase | Event | Main current |
|---|---|---|
| 0 | Rapid depolarisation | Fast Na+ influx (INa) |
| 1 | Early rapid repolarisation | Transient outward K+ (Ito) |
| 2 | Plateau | Ca2+ influx (L-type, ICaL) balanced by K+ efflux |
| 3 | Repolarisation | K+ efflux (IKr, IKs) |
| 4 | Resting / pacemaker | IK1 (resting); If ("funny current") in nodal tissue |
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