Differential responses to endurance training in subsarcolemmal and intermyofibrillar mitochondria

Michael E. Bizeau, Wayne T. Willis, Jeffrey R. Hazel

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83 Scopus citations


To examine the effect of endurance training (6 wk of treadmill running) on regional mitochondrial adaptations within skeletal muscle, subsarcolemmal (SS) and intermyofibrillar (IMF) mitochondria were isolated from trained and control rat hindlimb muscles. Mitochondrial oxygen consumption (V̇O2) was measured polarographically by using the following substrates: 1 mM pyruvate + 1 mM malate (P+M), 10 mM 2-oxoglutarate, 45 μM palmitoyl-DL-carnitine + 1 mM malate, and 10 mM glutamate. Spectrophotometric assays of cytochrome-c reductase and NAD-specific isocitrate dehydrogenase (IDH) activity were also performed. Maximal (state III) and resting (state IV) V̇O2 were lower in SS than in IMF mitochondria in both trained and control groups. In SS mitochondria, training elicited significant 36 and 20% increases in state III V̇O2 with P+M and glutamate, respectively. In IMF mitochondria, training resulted in a smaller (20%), yet significant, increase in state III V̇O2 with P+M as a substrate, whereas state III V̇O2 increased 33 and 27% with 2-oxoglutarate and palmitoyl-DL-carnitine + malate, respectively. Within groups, cytochrome-c reductase and IDH activities were lower in SS when compared with IMF mitochondria. Training increased succinate-cytochrome-c reductase in both SS (30%) and IMF mitochondria (28%). IDH activity increased 32% in the trained IMF but remained unchanged in SS mitochondria. We conclude that endurance training promotes substantial changes in protein stoichiometry and composition of both SS and IMF mitochondria.

Original languageEnglish (US)
Pages (from-to)1279-1284
Number of pages6
JournalJournal of Applied Physiology
Issue number4
StatePublished - Oct 1998


  • Exercise
  • Mitochondrial respiration
  • Substrate oxidation

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)


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