You are here

Tissue-specific depression of mitochondrial proton leak and substrate oxidation in hibernating arctic ground squirrels

TitleTissue-specific depression of mitochondrial proton leak and substrate oxidation in hibernating arctic ground squirrels
Publication TypeJournal Article
Year of Publication2003
AuthorsBarger, JL, Brand, MD, Barnes, BM, Boyer, BB
JournalAmerican Journal of Physiology – Regulatory, Integrative and Comparative Physiology
Volume284
PaginationR1306-1313
Keywordsmetabolic depression
Abstract

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 squirrels (Spermophilus parryii). At an assay temperature of 37°C, state 3 and state 4 respiration rates and state 4 membrane potential were significantly depressed in liver mitochondria isolated from hibernators. In contrast, state 3 and state 4 respiration rates and membrane potentials were unchanged during hibernation in skeletal muscle mitochondria. The decrease in oxygen consumption of liver mitochondria was achieved by reduced activity of the set of reactions generating the proton gradient but not by a lowered proton permeability. These results suggest that mitochondrial proton conductance is unchanged during hibernation and that the reduced metabolism in hibernators is a partial consequence of tissue-specific depression of substrate oxidation.

Username Tag: