Damage to mitochondrial complex I during cardiac ischemia reperfusion injury is reduced indirectly by anti-anginal drug ranolazine

Abstract

Ranolazine (Ran), an anti-anginal drug, is a late Na+ channel current blocker that is also believed to attenuate fatty acid oxidation and mitochondrial respiratory complex I activity, especially during ischemia. In this study, we investigated if Ran's protective effect against cardiac ischemia/reperfusion (IR) injury is mediated at the mitochondrial level and specifically if respiratory complex I (NADH oxidoreductase) function is protected. We treated isolated and perfused guinea pig hearts with Ran just before 30 min ischemia and then isolated cardiac mitochondria at the end of 30 min ischemia and/or 30 min ischemia followed by 10 min reperfusion. We utilized spectrophotometric and histochemical techniques to assay complex I activity, western blot analysis for complex I subunit NDUFA9, electron paramagnetic resonance for activity of complex I Fe-S clusters, ELISA for determination of protein acetylation, native gel histochemical staining for respiratory supercomplex assemblies, and high pressure liquid chromatography for cardiolipin integrity; cardiac function was measured during IR. Ran treated hearts showed higher complex I activity and greater detectable complex I protein levels compared to untreated IR hearts. Ran treatment also led to more normalized electron transfer via Fe-S centers, supercomplex assembly and cardiolipin integrity. These improvements in complex I structure and function with Ran were associated with improved cardiac function after IR. However, these protective effects of Ran are not mediated by a direct action on mitochondria, but rather indirectly via cytosolic mechanisms that lead to less oxidation and better structural integrity of complex I.

Sarcoendoplasmic Reticulum Ca2+ ATPase. A Critical Target in Chlorine Inhalation–Induced Cardiotoxicity

“…Therapeutic effects of ranolazine occur via two mechanisms: (1) inhibition of late inward sodium current and, hence, prevention of Ca 21 overload in ischemic hearts; and (2) inhibition of fatty acid oxidation and shift of metabolism toward glucose oxidation (52). Therefore, ranolazine may preserve mitochondrial supercomplexes, in part by restoring cardiolipin and, hence, electron flux in mitochondrial Fe-S clusters (53). Ranolazine also has been shown to indirectly stabilize SERCA in hearts of dogs with mild cardiac failure (18).…”

Effects of Late Sodium Current Blockade on Ventricular Refibrillation in a Rabbit Model

“…27 It has been demonstrated that, after ischemia, ranolazine improves mitochondrial function and that ranolazine is also protective of mitochondria in ischemia reperfusion injury. [37][38][39] In a previous study, we have demonstrated that improvement of mitochondrial function is cardioprotective. 40 This may support the notion that ranolazine improves mitochondrial function after LDVF.…”

Genetically determined mitochondrial preservation and cardioprotection against myocardial ischemia-reperfusion injury in a consomic rat model

“…Our methods have been described in detail previously (1,12,(21)(22)(23). Unless otherwise indicated, all drugs were purchased from Sigma (St. Louis, MO).…”

“…The membrane was then stripped using stripping buffer (100 mM 2-mercaptoethanol, 2% SDS, 62.5 mM Tris·HCl pH 6.7) at 50°C, followed by three washes in TBSt. Equivalence of protein loading was confirmed with an antibody against cytochrome c oxidase (complex IV) subunit 1 (Invitrogen) since complex IV is relatively more resistant to IR injury than complex I (12). Densitometry was performed with Image J software.…”