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

Martin Jastroch, Kerry W Withers, Sigrid Stoehr, Martin Klingenspor
Physiological and Biochemical Zoology: PBZ 2009, 82 (5): 447-54
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.

Full Text Links

Find Full Text Links for this Article


You are not logged in. Sign Up or Log In to join the discussion.

Trending Papers

Remove bar
Read by QxMD icon Read

Save your favorite articles in one place with a free QxMD account.


Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"