Elevated Na is a dynamic and reversible modulator of mitochondrial metabolism in the heart.

Chung, Yu Jin; Hoare, Zoe; Baark, Friedrich; Yu, Chak Shun; Guo, Jia; Fuller, William; Southworth, Richard; Katschinski, Doerthe M et al. · Nat Commun · 2024

basic_science · Level V

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Abstract

Elevated intracellular sodium Na<sub>i</sub> adversely affects mitochondrial metabolism and is a common feature of heart failure. The reversibility of acute Na induced metabolic changes is evaluated in Langendorff perfused rat hearts using the Na/K ATPase inhibitor ouabain and the myosin-uncoupler para-aminoblebbistatin to maintain constant energetic demand. Elevated Na<sub>i</sub> decreases Gibb's free energy of ATP hydrolysis, increases the TCA cycle intermediates succinate and fumarate, decreases ETC activity at Complexes I, II and III, and causes a redox shift of CoQ to CoQH<sub>2</sub>, which are all reversed on lowering Na<sub>i</sub> to baseline levels. Pseudo hypoxia and stabilization of HIF-1α is observed despite normal tissue oxygenation. Inhibition of mitochondrial Na/Ca-exchange with CGP-37517 or treatment with the mitochondrial ROS scavenger MitoQ prevents the metabolic alterations during Na<sub>i</sub> elevation. Elevated Na<sub>i</sub> plays a reversible role in the metabolic and functional changes and is a novel therapeutic target to correct metabolic dysfunction in heart failure.

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