Futile cycling of protons across the mitochondrial inner membrane accounts for 20 % or more of the total standard metabolic rate of a rat. Approximately 15 % of this total is due to proton leakage inside the skeletal muscle alone. This study examined whether the rate of proton leak is down-regulated as a part of a coordinated response to energy conservation during metabolic depression in cold-submerged frogs. We compared the proton leak rate of skeletal muscle mitochondria isolated from frogs at different stages of hibernation (control, 1 month and 4 months of submergence in normoxia and hypoxia). The kinetics of mitochondrial proton leak rate was unaltered throughout normoxic and hypoxic submergence. The state 4 respiration rates did not differ between control animals and frogs hibernating in normoxia. In contrast, the state 4 respiration rates obtained from frogs submerged in hypoxic water for 4 months were half those of control animals. This 50 % reduction in respiration rate in hypoxic hibernation was due to a reduction in electron transport chain activity and consequent decrease in mitochondrial membrane potential. We conclude that proton leak rate is reduced during metabolic depression as a secondary result of a decrease in electron transport chain activity, but that the proton conductance is unchanged. In addition, we show that the rate of proton leakage and the activity of the electron transport chain are lower in frogs than in rats, strengthening the observation that mitochondria from ectotherms have a lower proton conductance than mitochondria from endotherms.
The effect of metabolic depression on proton leak rate in mitochondria from hibernating frogs
J. St-Pierre, M.D. Brand, R.G. Boutilier; The effect of metabolic depression on proton leak rate in mitochondria from hibernating frogs. J Exp Biol 1 May 2000; 203 (9): 1469–1476. doi: https://doi.org/10.1242/jeb.203.9.1469
Download citation file:
Advertisement
Cited by
So long Andy and welcome Monica
We say a fond farewell to Andy Biewener who, after 20 years and steering hundreds of manuscripts through peer review, will be stepping down from his role as JEB Editor. We are delighted to welcome Monica Daley to the team in his place.
Call for papers - Building New Paradigms in Comparative Physiology and Biomechanics
Our upcoming special issue is welcoming submissions until 31 July 2021. The special issue will be published in early 2022 and will be widely promoted online and at key global conferences.
Supporting early-career researchers
As a journal published by The Company of Biologists, we champion early-career researchers. Find out more about the practical solutions available to help this vital community navigate the first stages of their careers.
Neuroethology of number sense across the animal kingdom
Andreas Nieder considers the fundamentally different types of brains of diverse and distantly related animal species that give rise to number skills across the animal kingdom.
Hiking trails ideal for sauntering grizzlies
New measurements reveal that grizzly bears use similar amounts of energy as humans when walking and prefer to take routes with a gradient of less than 10%, which explains why they sometimes turn up on human hiking trails that are shallow for our use and are also ideal for grizzlies.
Upcoming grant deadlines
Grants awarded by The Company of Biologists help scientists travel, attend events and host sustainable activities. Make a note of the upcoming application deadlines and find out more about the grants on offer:
Sustainable Conferencing Grants
17 May 2021
Travelling Fellowships
31 May 2021
Scientific Meeting Grants
4 June 2021