Heterogeneous bioenergetic behaviour of subsarcolemmal and intermyofibrillar mitochondria in fed and fasted rats.
This study was designed to examine energetic behaviour of skeletal muscle subsarcolemmal and intermyofibrillar mitochondrial populations. The data show that subsarcolemmal mitochondria exhibited a lower degree of coupling and efficiency than intermyofibrillar ones, and can therefore be considered less efficient at producing ATP. In addition, subsarcolemmal mitochondria showed an increased sensitivity to palmitate-induced uncoupling, in line with high adenine nucleotide translocator content and decreased oxidative damage. We then determined the effect of 24 h fasting on energetic characteristics of skeletal muscle mitochondrial populations. We found that fasting enhanced proton leak and decreased the degree of coupling and efficiency, both in the absence and in the presence of palmitate only in subsarcolemmal mitochondria. Moreover, this mitochondrial population showed lower oxidative damage, probably due to a counter-regulatory mechanism mediated by uncoupling protein 3. Subsarcolemmal and intermyofibrillar mitochondria appear to exhibit different energetic characteristics and can be differently affected by physiological stimuli.
Mollica
M P
MP
Dipartimento delle Scienze Biologiche, Sezione di Fisiologia, Via Mezzocannone 8, 80134 Naples, Italy. liverini@unina.it
Lionetti
L
L
Crescenzo
R
R
D'Andrea
E
E
Ferraro
M
M
Liverini
G
G
Iossa
S
S
D000154:Aconitate Hydratase / Q000378:metabolism; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism; D004734:Energy Metabolism; D005215:Fasting; D005227:Fatty Acids / Q000378:metabolism; D066298:In Vitro Techniques; D007473:Ion Channels; D008297:Male; D008564:Membrane Potentials; D008931:Mitochondria, Muscle / Q000378:metabolism* / Q000502:physiology; D000226:Mitochondrial ADP, ATP Translocases / Q000378:metabolism; D024101:Mitochondrial Proteins; D018482:Muscle, Skeletal / Q000378:metabolism*; D009210:Myofibrils / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012508:Sarcolemma / Q000378:metabolism*; D013482:Superoxide Dismutase / Q000378:metabolism; D000071247:Uncoupling Protein 3
D002352:Carrier Proteins; D005227:Fatty Acids; D007473:Ion Channels; D024101:Mitochondrial Proteins; C000604394:Ucp3 protein, rat; D000071247:Uncoupling Protein 3; D000226:Mitochondrial ADP, ATP Translocases; D013482:Superoxide Dismutase; D000154:Aconitate Hydratase; D010100:Oxygen