Skeletal muscle mitochondrial efficiency and uncoupling protein 3 in overeating rats with increased thermogenesis.
To establish whether changes in skeletal muscle mitochondrial efficiency contribute to increased energy expenditure and decreased metabolic efficiency of overeating rats with increased thermogenesis, we measured basal proton leak, fatty acid-induced uncoupling and uncoupling protein 3 (UCP3) content in subsarcolemmal and intermyofibrillar skeletal muscle mitochondria. Intermyofibrillar, but not subsarcolemmal, mitochondria from rats with increased thermogenesis exhibited a lower proton leak compared with controls. In both mitochondrial populations from rats with increased thermogenesis, fatty acid-induced uncoupling was increased significantly and a small recoupling effect of GDP was detected. In addition, intermyofibrillar and subsarcolemmal mitochondria from rats with increased thermogenesis showed higher UCP3 contents than controls. These results point out that metabolic efficiency in subsarcolemmal and intermyofibrillar mitochondria from rats with increased thermogenesis is differently regulated. In fact, in intermyofibrillar mitochondria both basal proton leak and fatty acid-induced uncoupling are altered, while in subsarcolemmal mitochondria only fatty acid-induced uncoupling increases. Both mitochondrial populations in skeletal muscle cells from rats with increased thermogenesis display an increased fatty acid-induced uncoupling and UCP3 content, which could contribute to avoiding obesity.
Iossa
Susanna
S
Department of General and Environmental Physiology, University of Naples Federico II, Via Mezzocannone 8, I-80134, Naples, Italy. susiossa@unina.it
Mollica
Maria Pia
MP
Lionetti
Lillà
L
Crescenzo
Raffaella
R
Botta
Monica
M
Samec
Sonia
S
Solinas
Giovanni
G
Mainieri
Davide
D
Dulloo
Abdul G
AG
Liverini
Giovanna
G
D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D004041:Dietary Fats / Q000008:administration & dosage; D004734:Energy Metabolism; D005227:Fatty Acids / Q000494:pharmacology; D006153:Guanosine Diphosphate / Q000494:pharmacology; D006963:Hyperphagia / Q000503:physiopathology*; D007473:Ion Channels; D008297:Male; D008931:Mitochondria, Muscle / Q000502:physiology*; D024101:Mitochondrial Proteins; D018482:Muscle, Skeletal / Q000503:physiopathology*; D009210:Myofibrils / Q000378:metabolism; D011522:Protons; D051381:Rats; D017208:Rats, Wistar; D012508:Sarcolemma / Q000378:metabolism; D022722:Thermogenesis; D014475:Uncoupling Agents / Q000494:pharmacology; D000071247:Uncoupling Protein 3
D002352:Carrier Proteins; D004041:Dietary Fats; D005227:Fatty Acids; D007473:Ion Channels; D024101:Mitochondrial Proteins; D011522:Protons; C000604394:Ucp3 protein, rat; D014475:Uncoupling Agents; D000071247:Uncoupling Protein 3; D006153:Guanosine Diphosphate