Muscle fiber contractile type influences the regulation of mitochondrial function.
Mitochondrial respiratory rates and regulation by phosphate acceptors were studied on permeabilized fiber bundles differing in their myosin heavy chain profiles. The acceptor control ratio, an indicator of oxidation to phosphorylation coupling, and mitochondrial K(m) for ADP were the highest in type I, intermediate in mixed IIa/IIx and the lowest in IIx and predominantly IIb fiber bundles. A functional coupling between mitochondrial creatine kinase and oxidative phosphorylation occurred in type I and IIa/IIx fiber bundles, exclusively. Our study suggests that mitochondrial functioning in fast IIa fibers is closer to that of the slow/I than fast IIx or IIb fibers.
Gueguen
Naig
N
INRA, Unité Mixte de Recherche Systèmes d'Elevage et Nutrition Animale et Humaine, Domaine de la Prise, Saint-Gilles, France.
Lefaucheur
Louis
L
Fillaut
Martine
M
Herpin
Patrick
P
D000244:Adenosine Diphosphate / Q000378:metabolism; D000818:Animals; D019069:Cell Respiration / Q000502:physiology*; D003401:Creatine / Q000494:pharmacology; D003402:Creatine Kinase / Q000378:metabolism; D066298:In Vitro Techniques; D007700:Kinetics; D008297:Male; D008931:Mitochondria, Muscle / Q000201:enzymology / Q000378:metabolism*; D018656:Muscle Fibers, Fast-Twitch / Q000166:cytology* / Q000378:metabolism*; D018657:Muscle Fibers, Slow-Twitch / Q000166:cytology* / Q000378:metabolism*; D011817:Rabbits
D000244:Adenosine Diphosphate; D003402:Creatine Kinase; D003401:Creatine