The mechanism of ranolazine action to reduce ischemia-induced diastolic dysfunction

Ischaemia of myocardium is associated with increases in the late sodium current (INa), intracellular sodium and calcium concentrations, calcium overload, and impairment of contractile relaxation (i.e. increased diastolic wall tension). An increase in diastolic wall tension compresses the vasculature and reduces nutritive blood flow, creating a positive feedback system that further impairs myocardial oxygenation and contractile function. Ranolazine reduces the late INa and, is expected to decrease sodium entry into ischaemic myocardial cells. As a consequence, ranolazine is proposed to reduce calcium uptake indirectly via the sodium/calcium exchanger and to preserve ionic homeostasis and reverse ischaemia-induced contractile dysfunction.