The primary hypotheses addressing the coincidence of fatigue and carbohydrate depletion in working skeletal muscle consider either pyruvate availability or citrate cycle inter- mediate levels. In this study we evaluated the role of pyruvate concentration on the relationship between ΔGATP and VO2. Mitochondria were isolated from rat hindlimb muscle and incubated in KCl-based media at 37°C. Various energy states were fixed by manipulating added phosphocreatine/creatine ratios in the presence of 25 U creatine kinase. VO2 was assessed polarographically. Malate (1.0 mM) was provided and pyruvate was stepwise added to yield 10 uM to 100 uM concentrations. Across all [pyruvate]. there was a strong linear relationship between ΔGATP and VO2. However, the slope of the relationship was highly dependent on [pyruvate]. The slope at 100 uM pyruvate was more than 4-fold greater than the slope at 10 uM pyruvate. These results indicate that, for a given VO2, a decrease in [pyruvate], in the physiological range, is associated with a fall in extramitochondrial energy state (ΔGATP).
|Original language||English (US)|
|State||Published - Mar 20 1998|
ASJC Scopus subject areas
- Molecular Biology