Analysis of Branched‐Chain α‐Keto Acid Dehydrogenase Complex (BCKDC) Activity and Activity State in Rat Skeletal Muscle by Isotope Ratio Mass Spectrometry (IRMS) using
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            C‐Labeled Stable Isotope Substrate

Starvation does not change the actual activity per g of tissue of the branched-chain 2-oxo acid dehydrogenase in skeletal muscles, but affects the total activity to a different extent, depending on the muscle type. The activity state (proportion of the enzyme present in the active state) does not change in diaphragm and decreases in quadriceps muscle. Liver and kidney show an increase of both activities, without a change of the activity state. In heart and brain no changes were observed. Related to organ wet weights, the actual activity present in the whole-body muscle mass decreases on starvation, whereas the activities present in liver and kidney do not change, or increase slightly. Exercise (treadmill-running) of untrained rats for 15 and 60 min causes a small increase of the actual activity and the activity state of the branched-chain 2-oxo acid dehydrogenase complex in heart and skeletal muscle. Exercise for 1 h, furthermore, increased the actual and the total activity in liver and kidney, without a change of the activity state. In brain no changes were observed. The actual activity per g of tissue in skeletal muscle was less than 2% of that in liver and kidney, both before and after exercise and starvation. Our data indicate that the degradation of branched-chain 2-oxo acids predominantly occurs in liver and to a smaller extent in kidney and skeletal muscle in fed, starved and exercised rats.

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[22] Assay of total complex and activity state of branched-chain α-keto acid dehydrogenase complex and of activator protein in mitochondria, cells, and tissues

Methods in Enzymology - Branched-Chain Amino Acids ◽

10.1016/s0076-6879(88)66024-1 ◽

1988 ◽

pp. 175-189 ◽

Cited By ~ 9

Author(s):

Philip A. Patston ◽

Joseph Espinal ◽

Mark Beggs ◽

Philip J. Randle

Keyword(s):

Keto Acid ◽

Acid Dehydrogenase ◽

Activator Protein ◽

Activity State ◽

Branched Chain ◽

Acid Dehydrogenase Complex ◽

Dehydrogenase Complex

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Activation of branched-chain alpha-keto acid dehydrogenase complex by exercise: effect of high-fat diet intake

Journal of Applied Physiology ◽

10.1152/jappl.1990.68.1.161 ◽

1990 ◽

Vol 68 (1) ◽

pp. 161-165 ◽

Cited By ~ 22

Author(s):

Y. Shimomura ◽

T. Suzuki ◽

S. Saitoh ◽

Y. Tasaki ◽

R. A. Harris ◽

...

Keyword(s):

Amino Acids ◽

Branched Chain Amino Acids ◽

Enzyme Complex ◽

Keto Acid ◽

High Fat ◽

Acid Dehydrogenase ◽

Activity State ◽

Branched Chain ◽

Acid Dehydrogenase Complex ◽

Dehydrogenase Complex

The effect of exercise on the activity of branched-chain alpha-keto acid dehydrogenase complex in liver and muscle was studied in rats fed a high-fat (FAT) or a high-carbohydrate (CHO) diet. Both diet groups of rats were offered isoenergetic diets by a meal-feeding method and were trained by treadmill running. On the final day of the experiment, half of the rats in each diet group were exercised by 2 h of running just before they were killed. The activity state of the enzyme complex was elevated maximally by exercise in liver of rats fed the FAT diet but not in liver of rats fed the CHO diet, suggesting that catabolism of branched-chain amino acids in rat liver during exercise was enhanced by the FAT diet. The activity state of the enzyme complex in muscle was enhanced by exercise in both groups of rats, but a significant difference was not observed between the groups. The concentration of branched-chain amino acids was elevated in liver and muscle by exercise in both groups of rats, but the elevated levels in liver were lower in rats fed the FAT diet than in those fed the CHO diet. Serum branched-chain amino acid concentrations were significantly lower in rested rats fed the FAT diet than in those fed the CHO diet, and the leucine and isoleucine concentrations in the former were elevated by exercise, but the serum concentrations in the latter were not significantly affected by exercise. ATP and ADP concentrations in muscle were not significantly affected by either diet or exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

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