Ranolazine

Ranolazine is found to bind more tightly to the inactivated state than the resting state of the sodium channel underlying I(NaL), with apparent dissociation constants K(dr)=7.47 mM and K(di)=1.71 mM, respectively. Ranolazine at 5 mM and 10 mM reversibly shortens the duration of TCs and abolishes the after contraction.^[1] Ranolazine inhibits the late component of INa and attenuates prolongation of action potential duration when late INa is increased, both in the absence and presence of IK-blocking drugs. Ranolazine (10 mM) reduces by 89% the 13.6-fold increase in variability of APD caused by 10 nM ATX-II. ^[2]

Ranolazine significantly and reversibly shortens the action potential duration (APD) of myocytes stimulated at either 0.5 or 0.25 Hz in a concentration-dependent manner in left ventricular myocytes of dogs. ^[1] Ranolazine (10 mM) significantly increases glucose oxidation 1.5-fold to 3-fold under conditions in which the contribution of glucose to overall ATP production is low (low Ca, high FA, with insulin), high (high Ca, low Fa, with pacing), or intermediate in working heart of rats. Ranolazine (10 mM) similarly increases glucose oxidation in normoxic Langendorff hearts (high Ca, low FA; 15 mL/min) of rats. Ranolazine significantly improves functional outcome in reperfused ischemic working hearts, which is associated with significant increases in glucose oxidation. ^[3]