Mitochondrial proton conductance in skeletal muscle of a cold-exposed marsupial, Antechinus flavipes, is unlikely to be involved in adaptive non-shivering thermogenesis but displays increased sensitivity towards carbon-centered radicals

Jastroch, Martin and Withers, Kerry and Stoehr, Sigrid and Klingenspor, Martin (2009) Mitochondrial proton conductance in skeletal muscle of a cold-exposed marsupial, Antechinus flavipes, is unlikely to be involved in adaptive non-shivering thermogenesis but displays increased sensitivity towards carbon-centered radicals. Physiological and Biochemical Zoology, 82 (5). pp. 447-454. ISSN 1552-2152

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Abstract

The organs and molecular mechanisms contributing to adaptive thermogenesis in marsupials are not known because some species apparently lack brown adipose tissue (BAT). The increased oxidative capacity and presence of uncoupling protein 3 (UCP3) in skeletal muscle led to speculations on whether uncoupled respiration sustains endothermy in the cold, as found for BAT. Here, we investigated the role of mitochondrial proton conductance in the small Australian marsupial Antechinus flavipes during cold exposure. Although there was a tendency toward higher oxidative capacity in skeletal muscle, indicating metabolic adjustments to the cold, we observed no change in basal proton conductance of isolated myotubular and liver mitochondria. In eutherians, 4-hydroxynonenal (HNE) is an activator of mitochondrial uncoupling mediated by UCP3 and ANT (adenine nucleotide translocase). In the marsupial A. flavipes, proton conductance in myotubular mitochondria could be induced by HNE selectively in the cold-acclimated group. Induced uncoupling activity could be attributed to the ANT as judged by inhibition with carboxyatractylate, while GDP, a putative inhibitor of rodent UCP3, had no detectable effects on marsupial UCP3. In contrast to previous expectations, basal proton conductance in the myotubular mitochondria of marsupials does not contribute to adaptive thermogenesis, as found for eutherian BAT. Increased sensitivity of proton conductance to HNE by the ANT suggests a greater requirement for mild uncoupling activity that may convey protection from lipid peroxidation and mitigate reactive oxygen species production during cold stress.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Published version deposited in accordance with the copyright policy of the publisher.
Depositing User: Dr Kerry Withers
Faculty / Department / School: Historic - Faculty of Sciences - Department of Biological and Physical Sciences
Date Deposited: 17 Jun 2010 23:35
Last Modified: 02 Jul 2013 23:34
Uncontrolled Keywords: marsupials; Antechinus; body temperature regulation; brown adipose tissue; cold temperature physiological effect; cell respiration; peroxidation
Fields of Research (FOR2008): 06 Biological Sciences > 0606 Physiology > 060604 Comparative Physiology
Socio-Economic Objective (SEO2008): E Expanding Knowledge > 97 Expanding Knowledge > 970106 Expanding Knowledge in the Biological Sciences
Identification Number or DOI: doi: 10.1086/603631
URI: http://eprints.usq.edu.au/id/eprint/6508

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