Cardiac Arrhythmias: Difference between revisions

Immediately following rapid depolarization, the inactivation of the Na⁺ channel (I_Na) and subsequent activation of the outward K⁺ channel (I_to) and the Na⁺/Ca²⁺ exchanger (I_Na,Ca), which exchanges 3 Na⁺ for 1 Ca²⁺, produces a early rapid repolarization. Due to the limited role of the Na⁺ channel in the upstroke of sinus node and AV node cells and the subsequent slower depolarization, this rapid repolarisation is not visible in their action potentials (Figure 2).