Ischemic-induced hyperkalemia (accumulation of extracellular potassium ions) predisposes the heart to the development of lethal reentrant ventricular arrhythmias. This phenomenon exhibits a triphasic timecourse and is thought to be mediated by a combination of three mechanisms: (a) increased cellular K⁺ efflux; (b) decreased cellular K⁺ influx; and (c) shrinkage of the extracellular space. These ischemia induced electrophysiological changes are driven by an impaired cellular metabolism. However, the relative contributions of these mechanisms, as well as the origin of the triphasic profile, have proven to be difficult to determine experimentally. In this study, the changes in metabolite concentrations that arise during 15 minutes of zero flow global ischemia were incorporated into a dynamic model of cellular electrophysiology, which was extended to include a metabolically-sensitive description of the Na⁺-K⁺ pump and the K_ATP channel, in addition to cell volume regulation. The coupling of altered K⁺ fluxes and cell volume regulation enables an integrative simulation of ischemic hyperkalemia. These simulations were able to quantitatively reproduce experimental measurements of the accumulation of extracellular potassium ions during 15 minutes of simulated ischemia, both with respect to the degree of potassium loss as well as the triphasic timecourse. Analysis of the model indicates that the inhibition of the Na⁺-K⁺ pump is the dominant factor underlying this hyperkalemic behavior, accounting for approximately 85% of the observed extracellular K⁺ accumulation. It was found that the balance between activation and inhibition of the Na⁺-K⁺ pump, effected by the changing metabolite and ion concentrations (in particular, [ADP]), give rise to the triphasic profile associated with ischemic-hyperkalemia.