Effect of Na⁺-K⁺ pump inhibition on extracellular potassium accumulation during myocardial ischemia: a simulation study

Acute myocardial ischemia leads to fast extracellular K⁺ accumulation and subsequent development of reentrant arrhythmias. Despite the importance of this phenomenon, mechanisms responsible for cellular K⁺ loss are still unknown. One possible cause is a decrease of K⁺ influx due to a partial inhibition of Na⁺-K⁺ pump activity. The maximum Na ⁺-K⁺ pump current of Luo-Rudy phase II action potential model was modified to study the effect of pump inhibition on extracellular potassium accumulation in the absence of coronary flow. The authors' results show that Na⁺-K⁺ pump inhibition could considerably contribute to extracellular K⁺ accumulation during acute myocardial ischemia. However, since a decrease of I^NaKNAK reduces KC driving force and K⁺ outward current, other mechanisms than Na⁺-K⁺ pump inhibition should necessarily contribute to the enhancement of unidirectional K⁺ efflux experimentally observed during acute myocardial ischemia