Chicco 2022 MitoFit

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Chicco 2022 MitoFit

Chicco AJ, Zilhaver PT, Whitcomb LA, Fresa KJ, Izon CS, Gonzalez-Franquesa A, Izon CS, Dometita C, Irving BA, Garcia-Roves PM (2022) Resolving the Rotenone Paradox: elucidating the complexity of multi-substrate respirometry protocols. MitoFit Preprints 2022.17. https://doi.org/10.26124/mitofit:2022-0017

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Resolving the Rotenone Paradox: elucidating the complexity of multi-substrate respirometry protocols

Chicco Adam J, Zilhaver Philip T, Whitcomb Luke A, Fresa Kyle J, Izon Cheyanne S, Gonzalez-Franquesa Alba, Dometita Crystal, Irving Brian A, Garcia-Roves Pablo Miguel (2022-05-02) MitoFit Prep

Abstract: Multi-substrate respirometry protocols are frequently used to resolve the relative contributions of NADH-producing (N-pathway or CI-linked) substrates and succinate (S-pathway or CII-linked substrate) to mitochondrial oxygen consumption rate (J_O2). Similarly, rotenone (a selective CI inhibitor) is utilized in the presence of N+S substrates to deduce the contribution of N-pathway flux to the total (N+S-pathway) J_O2. However, under S- and some N+S pathway states, rotenone elicits a paradoxical increase in J_O2, revealing a complex interaction of N- and S-pathway substrate oxidation on J_O2 in vitro. Herein, we demonstrate inhibitory effects of >1 mM malate or malonate (a CII inhibitor) on JO2 supported by pyruvate and/or glutamate, suggesting that endogenous succinate oxidation interacts with malate concentration to potently regulate J_O2 supported by N-pathway substrates in a tissue-specific manner. Potential mechanisms are discussed to stimulate further experimentation aimed at elucidating the biological bases for variations in NS-pathway flux in multi-substrate respirometry protocols.

• Keywords: Mitochondrial respiration, electron transport chain, succinate, glutamate, oxidative phosphorylation, high-resolution respirometry • Bioblast editor: Tindle-Solomon L

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