Neufer 2014 Abstract MiP2014
|Assessing ATP production and oxygen consumption simultaneously in permeabilized fibers: ATP/O.|
The biochemical efficiency of oxidative phosphorylation (OXPHOS), quantified as the amount of ATP produced per oxygen atom consumed (ATP/O or ~P/O), is vital to maintaining proper myocyte energetics. However, despite its central importance, it is difficult to experimentally determine the ~P/O ratio as a function of metabolic demand, and therefore, the relationship between OXPHOS efficiency and metabolic demand is poorly understood. O2 consumption (high-resolution respirometry) and ATP production (determined fluorometrically using a 2-deoxyglucose – hexokinase – glucose-6-phosphate dehydrogenase – NADP+ respiratory clamp system ), rates were measured simultaneously in permeabilized mouse oxidative and glycolytic skeletal muscle fiber bundles using a customized Oroboros Oxygraph-2k.
With pyruvate+malate (5+2 mM) as substrate, at low [ADP] (5-20 µM), the ~P/O ratio increased as a function of [ADP], independent of an increase in O2 consumption. Maximal ~P/O peaked at ~2.0 and was not different between oxidative and glycolytic muscle. Pharmacological inhibition of adenylate kinase decreased ATP production rate but did not alter ADP-dependent increases in OXPHOS efficiency.
These findings suggest that mitochondria respond to low levels of metabolic demand by initially increasing OXPHOS efficiency.
Labels: MiParea: Respiration
Organism: Mouse Tissue;cell: Skeletal muscle Preparation: Permeabilized tissue
Regulation: ADP, ATP production, Coupling efficiency;uncoupling Coupling state: OXPHOS
HRR: Oxygraph-2k Event: A4, Oral MiP2014
1-East Carolina Diabetes Obesity Inst; 2-Dep Kinesiolog; 3-Dep Physiol; 4-Dep Pharmacolog Toxicolog; East Carolina Univ, Greenville, NC, USA. – [email protected]
References and acknowledgements
Supported by: National Institute of Health R01 DK096907 (USA).
- Gouspillou G, Rouland R, Calmettes G, Deschodt-Arsac V, Franconi J-M, Bourdel-Marchasson I, Diolez P (2011) Accurate determination of the oxidative phosphorylation affinity for ADP in isolated mitochondria. PloS One 6:e20709.