Edit Publication: Pham 2014 Am J Physiol

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Abstract:	As approximately 80% of diabetics die from heart failure, understanding diabetic cardiomyopathy is crucial. Mitochondria occupy 35-40% of mammalian cardiomyocyte volume, supply 95% of the hearts' ATP, and diabetic heart mitochondria show impaired structure, arrangement and function. We predict that bioenergetic efficiencies are present in diabetic heart mitochondria; therefore we explored mitochondrial proton and electron handling by linking oxygen flux within streptozotocin (STZ)-induced-diabetic Sprague-Dawley rat heart tissues, to steady-state ATP synthesis, Reactive Oxygen Species (ROS) production, and mitochondrial membrane potential (Δ''Ψ''). By coupling high-resolution respirometers with purpose-built fluorometers, we followed Magnesium Green (ATP synthesis), Amplex Ultra Red (ROS production), and safranin-O (Δ''Ψ''). Relative to control rats, the mass-specific respiration of STZ-diabetic hearts was depressed in oxidative phosphorylating (OXPHOS) states. Steady-state ATP synthesis capacity was almost a third lower in STZ-diabetic heart and relative to O2 flux, this equates to an estimated 12% depression in OXPHOS efficiency. However, with anoxic transition, STZ-diabetic and control heart tissues showed similar ATP hydrolysis capacities through reversal of the F1/F0 ATP-synthase. STZ-diabetic cardiac mitochondria also produced more net ROS relative to oxygen flux (ROS/O) in OXP. While Δ''Ψ'' did not differ between groups, the time to develop Δ''Ψ'' with the onset of OXPHOS was protracted in STZ-diabetic mitochondria. ROS/O is higher in life-like OXPHOS states and potential delays in the time to develop Δ''Ψ'' may delay ATP synthesis with inter-beat fluctuations in ADP concentrations. Whereas diabetic cardiac mitochondria produce less ATP in normoxia, they consume as much ATP in anoxic infarct-like states.
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MiPareas:	Gender Respiration Instruments;methods mt-Biogenesis;mt-density mt-Structure;fission;fusion mt-Membrane mtDNA;mt-genetics nDNA;cell genetics Genetic knockout;overexpression Comparative MiP;environmental MiP Developmental biology Exercise physiology;nutrition;life style mt-Medicine Patients Pharmacology;toxicology mt-Awareness
Pathological states:	COPD Aging;senescence Alzheimer's Autism Cancer Cardiovascular Diabetes Inherited Infectious Myopathy Neurodegenerative Obesity Parkinson's Sepsis Other
Stress conditions:	Hypoxia Cell death Cryopreservation Ischemia-reperfusion Permeability transition Oxidative stress;RONS Temperature Mitochondrial disease
Organism:	Pig Human Mouse Rat Guinea pig Bovines Horse Dog Rabbit Cat Other mammals Chicken Zebrafish Drosophila Artemia Caenorhabditis elegans Saccharomyces cerevisiae Birds Reptiles Amphibians Fishes Chelicerates Crustaceans Hexapods Myriapods Annelids Molluscs Nematodes Other invertebrates Fungi Plants Protists Eubacteria Archea Algae
Tissues;cells:	Fat Heart Skeletal muscle Nervous system Liver Kidney Lung;gill Islet cell;pancreas;thymus Endothelial;epithelial;mesothelial cell Blood cells Genital Other cell lines CHO HEK HeLa Neuroblastoma Fibroblast HUVEC Macrophage-derived Lymphocyte Platelet Stem cells
Preparations:	SMP Intact organism Intact organ Permeabilized cells Permeabilized tissue Homogenate Isolated mitochondria Chloroplasts Enzyme Oxidase;biochemical oxidation Intact cells
Enzyme:	Complex I Adenine nucleotide translocase Complex II;succinate dehydrogenase Complex III Complex IV;cytochrome c oxidase Complex V;ATP synthase Inner mt-membrane transporter Marker enzyme Supercomplex TCA cycle and matrix dehydrogenases Uncoupling protein
Regulation; kinetics:	pH Aerobic glycolysis ADP ATP ATP production AMP Calcium Coupling efficiency;uncoupling Cyt c Flux control Inhibitor Ion;substrate transport mt-Membrane potential Oxygen kinetics PCr;Cr Phosphate Redox state Substrate Temperature Threshold;excess capacity Uncoupler Fatty acid Amino acid Q-junction effect
Coupling:	ET LEAK ROUTINE OXPHOS
Pathways:	F N S Gp DQ CIV NS Other combinations ROX
High-resolution respirometry:	pH Oxygraph-2k TIP2k O2k-Fluorometer NO TPP Ca O2k-Spectrophotometer O2k-Manual O2k-Protocol Theory NextGen-O2k
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Free text: If the abstract is longer than 500 words, please enter additional information here. Demonstration of using Amplex Red, Safranin and Magnesium green methods with the O2k-Fluorescence Module. == Correction == An Oroboros Oxygraph-2k was used in this publication, whereas the Anton Paar/Oroboros Oxygraph was the first-generation instrument for high-resolution respirometry, which was replaced by the Oxygraph-2k in 2002. * ''Further details'': [[Gnaiger 2012 Abstract Bioblast-Gentle Science]] == Cited by == {{Template:Cited by Cardoso 2021 MitoFit MgG}}

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