CALL FOR PAPERS Mitochondrial Function/Dysfunction in Health and Disease Mitochondrial metabolic suppression and reactive oxygen species production in liver and skeletal muscle of hibernating thirteen-lined ground squirrels
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چکیده
Brown JCL, Chung DJ, Belgrave KR, Staples JF. Mitochondrial metabolic suppression and reactive oxygen species production in liver and skeletal muscle of hibernating thirteen-lined ground squirrels. Am J Physiol Regul Integr Comp Physiol 302: R15–R28, 2012. First published October 12, 2011; doi:10.1152/ajpregu.00230.2011.—During hibernation, animals cycle between periods of torpor, during which body temperature (Tb) and metabolic rate (MR) are suppressed for days, and interbout euthermia (IBE), during which Tb and MR return to resting levels for several hours. In this study, we measured respiration rates, membrane potentials, and reactive oxygen species (ROS) production of liver and skeletal muscle mitochondria isolated from ground squirrels (Ictidomys tridecemlineatus) during torpor and IBE to determine how mitochondrial metabolism is suppressed during torpor and how this suppression affects oxidative stress. In liver and skeletal muscle, state 3 respiration measured at 37°C with succinate was 70% and 30% lower, respectively, during torpor. In liver, this suppression was achieved largely via inhibition of substrate oxidation, likely at succinate dehydrogenase. In both tissues, respiration by torpid mitochondria further declined up to 88% when mitochondria were cooled to 10°C, close to torpid Tb. In liver, this passive thermal effect on respiration rate reflected reduced activity of all components of oxidative phosphorylation (substrate oxidation, phosphorylation, and proton leak). With glutamate malate and succinate, mitochondrial free radical leak (FRL; proportion of electrons leading to ROS production) was higher in torpor than IBE, but only in liver. With succinate, higher FRL likely resulted from increased reduction state of complex III during torpor. With glutamate malate, higher FRL resulted from active suppression of complex I ROS production during IBE, which may limit ROS production during arousal. In both tissues, ROS production and FRL declined with temperature, suggesting ROS production is also reduced during torpor by passive thermal effects.
منابع مشابه
Mitochondrial metabolic suppression and reactive oxygen species production in liver and skeletal muscle of hibernating thirteen-lined ground squirrels.
During hibernation, animals cycle between periods of torpor, during which body temperature (T(b)) and metabolic rate (MR) are suppressed for days, and interbout euthermia (IBE), during which T(b) and MR return to resting levels for several hours. In this study, we measured respiration rates, membrane potentials, and reactive oxygen species (ROS) production of liver and skeletal muscle mitochond...
متن کاملRegulation of succinate-fuelled mitochondrial respiration in liver and skeletal muscle of hibernating thirteen-lined ground squirrels.
Hibernating ground squirrels (Ictidomys tridecemlineatus) alternate between two distinct metabolic states throughout winter: torpor, during which metabolic rate (MR) and body temperature (Tb) are considerably suppressed, and interbout euthermia (IBE), during which MR and Tb briefly return to euthermic levels. Previous studies showed suppression of succinate-fuelled respiration during torpor in ...
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Chung DJ, Szyszka B, Brown JC, Hüner NP, Staples JF. Changes in the mitochondrial phosphoproteome during mammalian hibernation. Physiol Genomics 45: 389–399, 2013. First published April 9, 2013; doi:10.1152/physiolgenomics.00171.2012.—Mammalian hibernation involves periods of substantial suppression of metabolic rate (torpor) allowing energy conservation during winter. In thirteen-lined ground ...
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A significant proportion of standard metabolic rate is devoted to driving mitochondrial proton leak, and this futile cycle may be a site of metabolic control during hibernation. To determine if the proton leak pathway is decreased during metabolic depression related to hibernation, mitochondria were isolated from liver and skeletal muscle of nonhibernating (active) and hibernating arctic ground...
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Mammalian hibernation is associated with multiple physiological, biochemical, and molecular changes that allow animals to endure colder temperatures. We hypothesize that long non-coding RNAs (lncRNAs), a group of non-coding transcripts with diverse functions, are differentially expressed during hibernation. In this study, expression levels of lncRNAsH19 and TUG1 were assessed via qRT-PCR in liv...
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