Komelina 2015 Abstract MiP2015
|Artificial hypothermia of rats, as opposed to natural hibernation of ground squirrels Spermophilus undulatus, is not accompanied by inhibition of mitochondrial respiration in liver.|
In liver mitochondria of hibernating animals a suppression of oxidative phosphorylation is observed, which is irrespective of temperature and remains in experiments at 37°C. The mechanisms of implementation of this phenomenon are still under active debate. One of the assumptions is that the main cause of the suppression of oxidative phosphorylation is the inhibition of succinate dehydrogenase - complex II of the respiratory chain . Presented data in our work maintain another standpoint of the inhibition of respiratory chain in the segment of complex III . We demonstrate on the liver mitochondria of ground squirrels Spermophilus undulatus significant inhibition of phosphorylation rate and the maximum rate of respiration in hibernating animals in comparison with the active, using substrates oxidize both through complex I (glutamate, pyruvate) and the complex II (succinate), but found no change in the complex IV, under the oxidation of the artificial substrate TMPD, oxidized via cytochrome c. This indicates that the point of inhibition of mitochondrial respiration localized in the area after the complex II and prior to cytochrome c. It is unclear whether such inhibition is necessary for occurrence of hibernation state and if the property is unique to the natural hypometabolic state or is the consequence of any hypothermia. To find it out, we used normal homoeothermic animals (rats), which were immersed in artificial non-drug hypometabolism under conditions of hypoxia, hypercapnia and low ambient temperature, leading to a decrease in body temperature up to 15°C, and ground squirrels having the same temperature during entering in the hibernation. We found no difference in states of respiration of liver mitochondria between control and hypothermic rats. An artificial hypometabolism caused by hypothermia in nonhibernator mammals, is not accompanied by specific inhibition of mitochondrial respiration of liver, unlike in the natural hypometabolic state in hibernating ground squirrels.
Labels: MiParea: Respiration, Comparative MiP;environmental MiP
Stress:Oxidative stress;RONS, Temperature Organism: Rat, Other mammals Tissue;cell: Liver
Enzyme: Complex II;succinate dehydrogenase, Complex III, Complex IV;cytochrome c oxidase
Coupling state: ET
Event: E1, Poster MiP2015
1-Inst Cell Biophysics Russian Acad Sc, 2-Pushchino State Inst Natural Sc; Russia. – [email protected]
References and acknowledgements
- Muleme HM, Walpole AC, Staples JF (2006) Mitochondrial metabolism in hibernation: metabolic supression, temperature effects and substrate preferences. Physiol Biochem Zool 79:474–83.
- Brustovetsky NN, Mayevsky EI, Grishina EV, Gogvadze VG, Amerkhanov ZG (1989) Regulation of the rate of respiration and oxidative phosphorylation in liver mitochondria from hibernating ground squirrels, Citellus undulatus. Comp Biochem Physiol 94:537–41.