Granata 2023 MiP2023

Granata Cesare (2023) Novel mitochondrial respiration protocols reveal organ-specific reliance on ketone body metabolism in mice. MiP2023 Obergurgl AT.

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Granata Cesare (2023)

Event: MiP2023 Obergurgl AT

Introduction: Ketone bodies (KB) are important substrates for the heart, particularly during heart failure [1], kidney [2], brain, skeletal muscle, and other organs [3]. Despite their significant role in health and disease [4], very limited research is available investigating KB-linked ATP production in mammalian tissues [5]; moreover, no optimized protocols exist to assess the interplay of key enzymes involved in ketolysis and their respective contribution to OXPHOS capacity.
Methods: β-hydroxybutyrate (HBA)- and acetoacetate (ACA)-linked mitochondrial respiration was assessed in the heart left ventricle (LV), kidney, liver, brain, and soleus of ~18-24-week-old C57BL/6J female mice (n=6-8). A novel protocol combining KB-linked and complex I (CI)+CII-linked mitochondrial respiration was also devised.
Results and discussion: The Km for HBA was similar (~1 mM) in all tested organs. However, maximal HBA-linked respiration was different between organs (p<0.001), i.e., greater in the LV and liver (~32 pmol O2·s-1·mg-1), and lowest in the brain (5.2 pmol O2·s-1·mg-1). This protocol allows to determine β-hydroxybutyrate dehydrogenase activity in the liver. The Km for ACA and maximal ACA-linked respiration were greater in the kidney compared to the other tested organs (all p<0.050). Our novel KB+CI+CII combined respiration protocol indicated that the KB contribution to maximal respiration is 2- to 4-fold greater in the kidney (37.4%) compared to all other organs (all p<0.050), confirming the kidney’s reliance on KB metabolism [2]. Taken together, our novel protocols demonstrate an organ-specific response of mitochondrial respiration to different KBs.

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• Keywords: ketone body, mitochondrial respiration, ketolysis, mitochondria, high-resolution respirometry

• O2k-Network Lab: DE Duesseldorf Roden M

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Organism: Mouse

Event: E2