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