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.

Effect of low glycogen on carbohydrate and energy metabolism in human muscle during exercise

1992 ◽  
Vol 262 (4) ◽  
pp. C975-C979 ◽  
Author(s):  
M. K. Spencer ◽  
Z. Yan ◽  
A. Katz
Keyword(s):  
Muscle Glycogen ◽  
Glycogen Content ◽  
Tricarboxylic Acid Cycle ◽  
Work Load ◽  
Tricarboxylic Acid ◽  
Human Muscle ◽  
Acid Cycle ◽  
Before And After ◽  
Tricarboxylic Acid Cycle Intermediates ◽  
Femoris Muscle

The effect of preexercise muscle glycogen content on the metabolic responses to exercise has been investigated. Seven men cycled at a work load calculated to elicit 75% of maximal oxygen uptake [211 +/- 17 (SE) W] on two occasions: 1) to fatigue (37.2 +/- 5.3 min) and 2) at the same work load and for the same duration as the first. Biopsies were obtained from the quadriceps femoris muscle before and after exercise. Before the first experiment, muscle glycogen was lowered by exercise and diet, and before the second experiment, muscle glycogen was elevated. In the low-glycogen condition (LG), muscle glycogen decreased from 182 +/- 15 at rest to 7 +/- 4 mmol glucosyl units/kg dry wt at fatigue, while in the high-glycogen condition (HG), glycogen decreased from 725 +/- 31 at rest to 353 +/- 53 mmol glucosyl units/kg dry wt at the end of exercise. Hexose monophosphates were not increased after LG exercise but increased approximately fivefold after HG exercise. Lactate increased more during HG exercise (LG = 16 +/- 5, HG = 61 +/- 7 mmol/kg dry wt; P less than or equal to 0.001), whereas IMP increased more during LG (LG = 2.8 +/- 0.6, HG = 0.9 +/- 0.2 mmol/kg dry wt; P less than or equal to 0.05). The increases in the sum of tricarboxylic acid cycle intermediates (TCAI; citrate+malate+fumarate) and acetylcarnitine (which is in equilibrium with acetyl CoA) were significantly greater during HG exercise (P less than or equal to 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Fasting inhibits insulin-mediated glycolysis and anaplerosis in human skeletal muscle

1991 ◽  
Vol 261 (5) ◽  
pp. E598-E605 ◽  
Author(s):  
C. E. Castillo ◽  
A. Katz ◽  
M. K. Spencer ◽  
Z. Yan ◽  
B. L. Nyomba
Keyword(s):  
Skeletal Muscle ◽  
Human Skeletal Muscle ◽  
Glycogen Synthase ◽  
Fat Free Mass ◽  
Whole Body ◽  
Glucose Disposal ◽  
Glycolytic Flux ◽  
Quadriceps Femoris Muscle ◽  
Before And After ◽  
Femoris Muscle

uglycemic (approximately 5.5 mM) hyperinsulinemic (60 mU.m-2.min-1) clamps were performed for 2 h after a 10-h fast and after a prolonged (72-h) fast. Biopsies were obtained from the quadriceps femoris muscle before and after each clamp. The rate of whole body glucose disposal was approximately 50% lower during the clamp after the 72-h fast (P less than or equal to 0.001). The increase in carbohydrate (CHO) oxidation (which is proportional to glycolysis) during the clamp after the 10-h fast (to 13.8 +/- 1.5 mumol.kg fat free mass-1.min-1) was completely abolished during the clamp after the 72-h fast (1.7 +/- 0.6; P less than or equal to 0.001). During the clamp after the 10-h fast, postphosphofructokinase (PFK) intermediates and malate in muscle increased, whereas glutamate decreased (P less than or equal to 0.05-0.001 vs. basal) and citrate did not change. During the clamp after the 72-h fast, there were no significant changes in post-PFK intermediates or glutamate (P greater than 0.05 vs. basal), but there was a decrease in citrate (P less than or equal to 0.01 vs. basal). Euglycemic hyperinsulinemia increased glycogen synthase fractional activity in muscle under both conditions but to a greater extent after the 72-h fast (P less than or equal to 0.01). It is concluded that insulin (after 10-h fast) increases glycolytic flux and the content of malate in muscle, which is probably due to increased anaplerosis.(ABSTRACT TRUNCATED AT 250 WORDS)

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

Carbohydrate supplementation attenuates IMP accumulation in human muscle during prolonged exercise

1991 ◽  
Vol 261 (1) ◽  
pp. C71-C76 ◽  
Author(s):  
M. K. Spencer ◽  
Z. Yan ◽  
A. Katz
Keyword(s):  
Prolonged Exercise ◽  
Tricarboxylic Acid Cycle ◽  
Work Load ◽  
Tricarboxylic Acid ◽  
Human Muscle ◽  
Carbohydrate Supplementation ◽  
Large Expansion ◽  
Before And After ◽  
Tricarboxylic Acid Cycle Intermediates ◽  
Femoris Muscle

The effect of carbohydrate (CHO) ingestion on metabolic responses to exercise has been investigated. Subjects cycled at approximately 70% of maximal oxygen uptake to fatigue [135 +/- 17 (+/- SE) min] on the first occasion (control, CON) and at the same work load and duration on the second occasion but with addition of ingestion of CHO during the exercise. Biopsies were taken from the quadriceps femoris muscle before and after exercise. The sum of the hexose monophosphates (HMP), as well as lactate and alanine, in muscle was higher after CHO exercise (P less than or equal to 0.05, P less than or equal to 0.05, and P less than or equal to 0.01, respectively). Acetylcarnitine increased during exercise but was not significantly different between treatments after exercise (CON, 6.6 +/- 1.7; CHO, 10.0 +/- 1.2 mmol/kg dry wt; P = NS). The sum of the tricarboxylic acid cycle intermediates (TCAI; citrate + malate + fumarate) was increased during exercise and was higher after CHO exercise (2.34 +/- 0.32 vs. 1.68 +/- 0.17 mmol/kg dry wt; P less than or equal to 0.05). IMP was less than 0.1 mmol/kg dry wt at rest and increased to 0.77 +/- 0.26 (CON) and 0.29 +/- 0.11 mmol/kg dry wt (CHO) (P less than or equal to 0.05) during exercise. It was recently found that during prolonged exercise there is initially a rapid and large expansion of TCAI and glycogenolytic intermediates in human muscle followed by a continuous decline in TCAI and glycogenolytic intermediates [K. Sahlin, A. Katz, and S. Broberg. Am. J. Physiol. 259 (Cell Physiol. 28): C834-C841, 1990].(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Triheptanoin partially restores levels of tricarboxylic acid cycle intermediates in the mouse pilocarpine model of epilepsy

2013 ◽  
Vol 129 (1) ◽  
pp. 107-119 ◽  
Author(s):  
Mussie G. Hadera ◽  
Olav B. Smeland ◽  
Tanya S. McDonald ◽  
Kah Ni Tan ◽  
Ursula Sonnewald ◽  
...  
Keyword(s):  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Acid Cycle ◽  
Pilocarpine Model ◽  
Tricarboxylic Acid Cycle Intermediates

scholarly journals Metabolic phases during the development of granulation tissue

1967 ◽  
Vol 105 (1) ◽  
pp. 333-341 ◽  
Author(s):  
Kirsti Lampiaho ◽  
E. Kulonen
Keyword(s):  
Granulation Tissue ◽  
Collagen Synthesis ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Pentose Phosphate ◽  
Acid Cycle ◽  
Short Period ◽  
Tricarboxylic Acid Cycle Intermediates ◽  
Observation Period

1. The metabolism of incubated slices of sponge-induced granulation tissue, harvested 4–90 days after the implantation, was studied with special reference to the capacity of collagen synthesis and to the energy metabolism. Data are also given on the nucleic acid contents during the observation period. Three metabolic phases were evident. 2. The viability of the slices for the synthesis of collagen was studied in various conditions. Freezing and homogenization destroyed the capacity of the tissue to incorporate proline into collagen. 3. Consumption of oxygen reached the maximum at 30–40 days. There was evidence that the pentose phosphate cycle was important, especially during the phases of the proliferation and the involution. The formation of lactic acid was maximal at about 20 days. 4. The capacity to incorporate proline into collagen hydroxyproline in vitro was limited to a relatively short period at 10–30 days. 5. The synthesis of collagen was dependent on the supply of oxygen and glucose, which latter could be replaced in the incubation medium by other monosaccharides but not by the metabolites of glucose or tricarboxylic acid-cycle intermediates.

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