Pre‐ischaemic mitochondrial substrate constraint by inhibition of malate‐aspartate shuttle preserves mitochondrial function after ischaemia–reperfusion

Abstract

Mitochondrial dysfunction plays a central role in ischaemia-reperfusion (IR) injury. Pre-ischaemic administration of aminooxyacetate (AOA), an inhibitor of the malate-aspartate shuttle (MAS), provides cardioprotection against IR injury, although the underlying mechanism remains unknown. We hypothesized that a transient inhibition of the MAS during ischaemia and early reperfusion could preserve mitochondrial function at later phase of reperfusion in the IR-injured heart to the same extent as ischaemic preconditioning (IPC), which is a well-validated cardioprotective strategy against IR injury. In the present study, we show that pre-ischaemic administration of AOA preserved mitochondrial complex I-linked state 3 respiration and fatty acid oxidation during late reperfusion in IR-injured isolated rat hearts. AOA treatment also attenuated the excessive emission of mitochondrial reactive oxygen species during state 3 with complex I-linked substrates during late reperfusion, which was consistent with reduced oxidative damage in the IR-injured heart. As a result, AOA treatment reduced infarct size after reperfusion. These protective effects of MAS inhibition on the mitochondria were similar to those of IPC. Intriguingly, the protection of mitochondrial function by AOA treatment appears to be different from that of IPC because AOA treatment, but not IPC, downregulated myocardial tricarboxilic acid (TCA)-cycle intermediates at the onset of reperfusion. MAS inhibition thus preserved mitochondrial respiratory capacity and decreased mitochondrial oxidative stress during late reperfusion in the IR-injured heart, at least in part, via metabolic regulation of TCA cycle intermediates in the mitochondria at the onset of reperfusion.

Mitochondrial Structure and Function in the Metabolic Myopathy Accompanying Patients with Critical Limb Ischemia

“…Mitochondrial respiratory function was analyzed in duplicate at 37 • C using a two-chamber high-resolution respirometer (Oroboros Instruments, Innsbruck, Austria), as previously described [21,22]. Sequential titrations of substrates and inhibitors were performed in the following order and concentrations: (i) Glutamate (10 mmol L −1 ) and malate (2 mmol L −1 ) to assess state 2 leak respiration; (ii) ADP (5 mmol L −1 ) to assess state 3 respiration with complex I substrates; (iii) cytochrome c (10 µmol L −1 ) to assess the integrity of the outer mitochondrial membrane with an increase in respiration of >10% considered as a sign of damage leading to elimination of data; (iv) succinate (10 mmol L −1 ) to assess state 3 respiration with complex I and II substrates; (v) oligomycin (2 µg mL −1 ) to assess state 4 respiration; (vi) rotenone (0.5 µmol L −1 ) and antimycin A (2.5 mmol L −1 ) to asses residual oxygen consumption.…”

Aminooxyacetic acid attenuates post‐infarct cardiac dysfunction by balancing macrophage polarization through modulating macrophage metabolism in mice

“…For example, a recent study by Jespersen and colleagues showed pre‐ischaemic administration of AOAA reduced infarct size and protected the heart against ischaemia‐reperfusion injury. And, the authors owed its cardioprotection to the inhibiting of malate‐aspartate shuttle . Therefore, it is warranted to further investigate the cardioprotective mechanisms of AOAA using specific inhibitors of different enzymes separately.…”

“…And, the authors owed its cardioprotection to the inhibiting of malate-aspartate shuttle. 46 Therefore, it is warranted to further investigate the cardioprotective mechanisms of AOAA using specific inhibitors of different enzymes separately.…”

Sodium Glucose Transporter 2 (SGLT2) Inhibition does not Protect the Myocardium from Acute Ischemic Reperfusion Injury but Modulates Post- Ischemic Mitochondrial Function

“…Mitochondrial respiration was measured with high-resolution respirometry (Oroboros, Innsbruck, Austria) in permeabilized cardiac muscle fibers as previously described [5]. In short, two titration protocols were used to evaluate glucose and fatty acid linked respiration: Protocol 1 (complex I+II-linked respiration): State 2 respiration (GM) was assessed with malate (2 mM) and glutamate (10 mM).…”