Replenishment of Citric Acid Cycle Intermediates by the Purine Nucleotide Cycle in Rat Skeletal Muscle

1981 ◽  
pp. 131-149 ◽  
Author(s):  
JUAN J. ARAGÓN ◽  
KEITH TORNHEIM ◽  
MICHAEL N. GOODMAN ◽  
JOHN M. LOWENSTEIN
Keyword(s):  
Skeletal Muscle ◽  
Citric Acid ◽  
Citric Acid Cycle ◽  
Purine Nucleotide ◽  
Rat Skeletal Muscle ◽  
Acid Cycle ◽  
Purine Nucleotide Cycle

498-P: Resistance Exercise Rapidly Alters Citric Acid Cycle and Amino Acid Metabolism in Skeletal Muscle

Diabetes ◽  
2021 ◽  
Vol 70 (Supplement 1) ◽  
pp. 498-P
Author(s):  
MARK W. PATAKY ◽  
ARATHI PRABHA KUMAR ◽  
KATHERINE KLAUS ◽  
K. SREEKUMARAN NAIR
Keyword(s):  
Skeletal Muscle ◽  
Amino Acid ◽  
Citric Acid ◽  
Resistance Exercise ◽  
Amino Acid Metabolism ◽  
Citric Acid Cycle ◽  
Acid Metabolism ◽  
Acid Cycle

Purine nucleotide cycle as a possible anaplerotic process in rat skeletal muscle

1982 ◽  
Vol 38 (9) ◽  
pp. 1035-1037 ◽  
Author(s):  
P. W. D. Ścisłowski ◽  
Z. Aleksandrowicz ◽  
J. Świerczyński
Keyword(s):  
Skeletal Muscle ◽  
Purine Nucleotide ◽  
Rat Skeletal Muscle ◽  
Purine Nucleotide Cycle

Pyruvate and citric acid cycle carbon requirements in isolated skeletal muscle mitochondria

2004 ◽  
Vol 286 (3) ◽  
pp. C565-C572 ◽  
Author(s):  
Jeffrey I. Messer ◽  
Matthew R. Jackman ◽  
Wayne T. Willis
Keyword(s):  
Skeletal Muscle ◽  
Citric Acid ◽  
Citric Acid Cycle ◽  
Thermodynamic Force ◽  
Glycogen Depletion ◽  
Acid Cycle ◽  
Physiological Range ◽  
Skeletal Muscle Mitochondria

Carbohydrate depletion precipitates fatigue in skeletal muscle, but, because pyruvate provides both acetyl-CoA for mainline oxidation and anaplerotic carbon to the citric acid cycle (CAC), the mechanism remains obscure. Thus pyruvate and CAC kinetic parameters were independently quantified in mitochondria isolated from rat mixed skeletal muscle. Mitochondrial oxygen consumption rate ( Jo) was measured polarographically while either pyruvate or malate was added stepwise in the presence of a saturating concentration of the other substrate. These substrate titrations were carried out across a physiological range of fixed extramitochondrial ATP free energy states (ΔGP), established with a creatine kinase energy clamp, and also at saturating [ADP]. The apparent Km,malate for mitochondrial Jo ranged from 21 to 32 μM, and the apparent Km,pyruvate ranged from 12 to 26 μM, with both substrate Km values increasing as ΔGP declined. Vmax for both substrates also increased as ΔGP fell, reflecting thermodynamic control of Jo. Reported in vivo skeletal muscle [malate] are >10-fold greater than the Km,malate determined in this study. In marked contrast, the Km,pyruvate determined is near the [pyruvate] reported in muscle approaching exhaustion associated with glycogen depletion. When data were evaluated in the context of a linear thermodynamic force-flow (ΔGP- Jo) relationship, the ΔGP- Jo slope was essentially insensitive to changes in [malate] in the range observed in vivo but decreased markedly with declining [pyruvate] across the physiological range. Mitochondrial respiration is particularly sensitive to variations in [pyruvate] in the physiological range. In contrast, physiological [malate] exerts very little, if any, influence on mitochondrial pyruvate oxidation measured in vitro.

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