Lack of genetic polymorphism in human skeletal muscle enzymes of the tricarboxylic acid cycle

1987 ◽  
Vol 77 (2) ◽  
pp. 200-200 ◽  
Author(s):  
Martine Marcotte ◽  
Monique Chagnon ◽  
Claude C�t� ◽  
Marie-Christine Thibault ◽  
Marcel R. Boulay ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Genetic Polymorphism ◽  
Human Skeletal Muscle ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Muscle Enzymes ◽  
Acid Cycle

Epinephrine increases tricarboxylic acid cycle intermediates in human skeletal muscle

1991 ◽  
Vol 260 (3) ◽  
pp. E436-E439 ◽  
Author(s):  
M. K. Spencer ◽  
A. Katz ◽  
I. Raz
Keyword(s):  
Skeletal Muscle ◽  
Human Skeletal Muscle ◽  
Adenine Nucleotides ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Acid Cycle ◽  
Quadriceps Femoris Muscle ◽  
Before And After ◽  
Tricarboxylic Acid Cycle Intermediates ◽  
Femoris Muscle

The effects of epinephrine (E) and insulin infusions on the contents of tricarboxylic acid cycle intermediates (TCAI), adenine nucleotides and their catabolites, and amino acids in skeletal muscle have been investigated. Eight men were studied on two separate occasions: 1) during 120 min of euglycemic hyperinsulinemia (UH, approximately 5 mM; 40 mU.m-2.min-1) and 2) during UH while E was infused (UHE, 0.05 microgram.kg-1.min-1). Biopsies were taken from the quadriceps femoris muscle before and after each clamp. The sum of citrate, malate, and fumarate in muscle did not change significantly during UH (P greater than 0.05) but doubled during UHE (P less than 0.001). There were no significant changes in any of the adenine nucleotides, their catabolites (including inosine monophosphate), or aspartate during UH and UHE (P greater than 0.05); nor were there any significant changes in pyruvate or alanine contents during UH (P greater than 0.05). On the other hand, there were significant increases in pyruvate and alanine contents during UHE (P less than 0.01 and 0.05, respectively), suggesting that there was increased production of 2-oxoglutarate (a TCAI) via the alanine aminotransferase (ALT) reaction. It is concluded that E infusion increases the contents of TCAI in human skeletal muscle, and it is likely that at least part of the increase is attributable to increased flux through the ALT reaction.

scholarly journals Fibre-type specific modification of the activity and regulation of skeletal muscle pyruvate dehydrogenase kinase (PDK) by prolonged starvation and refeeding is associated with targeted regulation of PDK isoenzyme 4 expression

2000 ◽  
Vol 346 (3) ◽  
pp. 651-657 ◽  
Author(s):  
Mary C. SUGDEN ◽  
Alexandra KRAUS ◽  
Robert A. HARRIS ◽  
Mark J. HOLNESS
Keyword(s):  
Skeletal Muscle ◽  
Protein Expression ◽  
Pyruvate Dehydrogenase ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Pyruvate Dehydrogenase Kinase ◽  
Acid Cycle ◽  
Slow Twitch ◽  
Fast Twitch ◽  
Anterior Tibialis

Using immunoblot analysis with antibodies raised against recombinant pyruvate dehydrogenase kinase (PDK) isoenzymes PDK2 and PDK4, we demonstrate selective changes in PDK isoenzyme expression in slow-twitch versus fast-twitch skeletal muscle types in response to prolonged (48 h) starvation and refeeding after starvation. Starvation increased PDK activity in both slow-twitch (soleus) and fast-twitch (anterior tibialis) skeletal muscle and was associated with loss of sensitivity of PDK to inhibition by pyruvate, with a greater effect in anterior tibialis. Starvation significantly increased PDK4 protein expression in both soleus and anterior tibialis, with a greater response in anterior tibialis. Starvation did not effect PDK2 protein expression in soleus, but modestly increased PDK2 expression in anterior tibialis. Refeeding for 4 h partially reversed the effect of 48-h starvation on PDK activity and PDK4 expression in both soleus and anterior tibialis, but the response was more marked in soleus than in anterior tibialis. Pyruvate sensitivity of PDK activity was also partially restored by refeeding, again with the greater response in soleus. It is concluded that targeted regulation of PDK4 isoenzyme expression in skeletal muscle in response to starvation and refeeding underlies the modulation of the regulatory characteristics of PDK in vivo. We propose that switching from a pyruvate-sensitive to a pyruvate-insensitive PDK isoenzyme in starvation (a) maintains a sufficiently high pyruvate concentration to ensure that the glucose → alanine → glucose cycle is not impaired, and (b) may ‘spare’ pyruvate for anaplerotic entry into the tricarboxylic acid cycle to support the entry of acetyl-CoA derived from fatty acid (FA) oxidation into the tricarboxylic acid cycle. We further speculate that FA oxidation by skeletal muscle is both forced and facilitated by upregulation of PDK4, which is perceived as an essential component of the operation of the glucose-FA cycle in starvation.

Impairment of the Tricarboxylic acid cycle in skeletal muscle of zymosan treated rats

1993 ◽  
Vol 12 ◽  
pp. 20-21
Author(s):  
A.J.M. Wagenmakers ◽  
O.E. Rooyackers ◽  
W.H.M. Saris ◽  
P.B. Soeters
Keyword(s):  
Skeletal Muscle ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Acid Cycle

Acetyl-1-14C-l-carnitine Oxidation, Carnitine Acetyltransferase Activity, and CoA Content in Skeletal Muscle Mitochondria from Normal and Dystrophic Mice (Strain 129)

1972 ◽  
Vol 50 (7) ◽  
pp. 749-754 ◽  
Author(s):  
J. J. Jato-Rodriguez ◽  
C. H. Lin ◽  
A. J. Hudson ◽  
K. P. Strickland
Keyword(s):  
Skeletal Muscle ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Carnitine Acetyltransferase ◽  
Dystrophic Muscle ◽  
Mitochondrial Content ◽  
Acid Cycle ◽  
Skeletal Muscle Mitochondria ◽  
Leg Muscle ◽  
Dystrophic Mice

Mitochondria isolated from the hind leg muscle of normal and dystrophic mice (strain 129) were compared in their capacity to oxidize acetyl-1-14C-l-carnitine. Oxidation in the mitochondria from dystrophic animals was reduced by 80%. Carnitine acetyltransferase (EC 2.3.1.7) activity in the mitochondria was determined and showed a 35% reduction in the mitochondria from dystrophic muscle. A larger decrease (55%) was observed in the mitochondrial content of acid-soluble CoA. Although the combined decreases in carnitine acetyltransferase and CoA can largely account for the observed decrease in acetylcarnitine oxidation in the mitochondria isolated from dystrophic muscle, it is conceivable that some defect may still exist in the utilization of acetyl groups in the tricarboxylic acid cycle.

Effects of iron deficiency and training on mitochondrial enzymes in skeletal muscle

1987 ◽  
Vol 62 (6) ◽  
pp. 2442-2446 ◽  
Author(s):  
W. T. Willis ◽  
G. A. Brooks ◽  
S. A. Henderson ◽  
P. R. Dallman
Keyword(s):  
Skeletal Muscle ◽  
Iron Deficiency ◽  
Cytochrome C ◽  
Endurance Training ◽  
Tricarboxylic Acid Cycle ◽  
Interactive Effect ◽  
Tricarboxylic Acid ◽  
Mitochondrial Enzymes ◽  
Acid Cycle ◽  
Iron Deficient

We measured mitochondrial enzyme activities in skeletal muscle under conditions of iron deficiency and endurance training to assess the effects of these interventions on the contents and proportions of non-iron-containing and iron-dependent enzymes and proteins. Male Sprague-Dawley rats, 21 days of age, received a diet containing either 6 (iron deficient) or 50 mg iron/kg diet (iron sufficient). At 35 days of age animals were subdivided into sedentary and endurance training groups (running at 0.7 mph, 0% grade, 45 min/day, 6 days/wk). By 70 days of age, iron deficiency had decreased gastrocnemius muscle cytochrome c by 62% in sedentary animals. In contrast, the activities of tricarboxylic acid cycle enzymes were increased, remained unchanged or were slightly decreased, indicating that iron deficiency markedly altered mitochondrial composition. Endurance training increased cytochrome c (35%), tricarboxylic acid cycle enzymes (approximately 15%), and manganese superoxide dismutase (33%) in iron-deficient rats, whereas the same exercise regimen had no effect on the skeletal muscle of iron-sufficient animals. The interactive effect of dietary iron deficiency and mild exercise on mitochondrial enzymes suggests that adaptation to a training stimulus is, to some extent, geared to the relationship between the energy demand of exercise and the capacity for O2 transport and utilization.

Contribution of liver and skeletal muscle to alanine and lactate metabolism in humans

1990 ◽  
Vol 259 (5) ◽  
pp. E677-E684 ◽  
Author(s):  
A. Consoli ◽  
N. Nurjhan ◽  
J. J. Reilly ◽  
D. M. Bier ◽  
J. E. Gerich
Keyword(s):  
Skeletal Muscle ◽  
Plasma Glucose ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Lactate Metabolism ◽  
Muscle Lactate ◽  
Acid Cycle ◽  
Principal Source ◽  
Lactate Uptake ◽  
Uptake And Release

To quantitate alanine and lactate gluconeogenesis in postabsorptive humans and to test the hypothesis that muscle is the principal source of these precursors, we infused normal volunteers with [3–14C]lactate, [3–13C]alanine, and [6-3H]glucose and calculated alanine and lactate incorporation into plasma glucose corrected for tricarboxylic acid cycle carbon exchange, the systemic appearance of these substrates, and their forearm fractional extraction, uptake, and release. Forearm alanine and lactate fractional extraction averaged 37 +/- 3 and 27 +/- 2%, respectively; muscle alanine release (2.94 +/- 0.27 mumol.kg body wt-1.min-1) accounted for approximately 70% of its systemic appearance (4.18 +/- 0.31 mumol.kg body wt-1.min-1); muscle lactate release (5.51 +/- 0.42 mumol.kg body wt-1.min-1) accounted for approximately 40% of its systemic appearance (12.66 +/- 0.77 mumol.kg body wt-1.min-1); muscle alanine and lactate uptake (1.60 +/- 0.7 and 3.29 +/- 0.36 mumol.kg body wt-1.min-1, respectively) accounted for approximately 30% of their overall disappearance from plasma, whereas alanine and lactate incorporation into plasma glucose (1.83 +/- 0.20 and 4.24 +/- 0.44 mumol.kg body wt-1.min-1, respectively) accounted for approximately 50% of their disappearance from plasma. We therefore conclude that muscle is the major source of plasma alanine and lactate in postabsorptive humans and that factors regulating their release from muscle may thus exert an important influence on hepatic gluconeogenesis.

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