Cheng 2021 Comp Biochem Physiol B Biochem Mol Biol
| Cheng H, Munro D, Huynh K, Pamenter ME (2021) Naked mole-rat skeletal muscle mitochondria exhibit minimal functional plasticity in acute or chronic hypoxia. Comp Biochem Physiol B Biochem Mol Biol 255:110596. |
Cheng Hang, Munro Daniel, Huynh Kenny, Pamenter Matthew E (2021) Comp Biochem Physiol B Biochem Mol Biol
Abstract: Oxidative phosphorylation is compromised in hypoxia, but many organisms live and exercise in low oxygen environments. Hypoxia-driven adaptations at the mitochondrial level are common and may enhance energetic efficiency or minimize deleterious reactive oxygen species (ROS) generation. Mitochondria from various hypoxia-tolerant animals exhibit robust functional changes following in vivo hypoxia and we hypothesized that similar plasticity would occur in naked mole-rat skeletal muscle. To test this, we exposed adult subordinate naked mole-rats to normoxia (21% O2) or acute (4 h, 7% O2) or chronic hypoxia (4-6 weeks, 11% O2) and then isolated skeletal muscle mitochondria. Using high-resolution respirometry and a fluorescent indicator of ROS production, we then probed for changes in: i) lipid- (palmitoylcarnitine-malate), ii) carbohydrate- (pyruvate-malate), and iii) succinate-fueled metabolism, and also iv) complex IV electron transfer capacity, and v) H2O2 production. Compared to normoxic values, a) lipid-fueled uncoupled respiration was reduced ~15% during acute and chronic hypoxia, b) complex I-II capacity and the rate of ROS efflux were both unaffected, and c) complex II and IV uncoupled respiration were supressed ~16% following acute hypoxia. Notably, complex II-linked H2O2 efflux was 33% lower after acute hypoxia, which may reduce deleterious ROS bursts during reoxygenation. These mild changes in lipid- and carbohydrate-fueled respiratory capacity may reflect the need for this animal to exercise regularly in highly variable and intermittently hypoxic environments in which more robust plasticity may be energetically expensive. • Keywords: Electron transport system, High resolution respirometry, Oxidative phosphorylation, Reactive oxygen species, Succinate • Bioblast editor: Reiswig R • O2k-Network Lab: CA Ottawa Pamenter M
Labels: MiParea: Respiration
Stress:Oxidative stress;RONS, Hypoxia Organism: Other mammals Tissue;cell: Skeletal muscle Preparation: Isolated mitochondria
Coupling state: LEAK, OXPHOS, ET
Pathway: F, N, S, CIV, NS, ROX
HRR: Oxygraph-2k, O2k-Fluorometer
2021-07, AmR
