Branched-chain 2-oxo acid dehydrogenase complex activation by tetanic contractions in rat skeletal muscle

Yoshiharu Shimomura, Hisao Fujii, Masashige Suzuki, Noriaki Fujitsuka, Makoto Naoi, Satoru Sugiyama, Robert A. Harris

Research output: Contribution to journalArticle

24 Scopus citations

Abstract

Branched-chain 2-oxo acid dehydrogenase complex in rat skeletal muscle was activated by muscle contractions elicited by electrical stimulation. This activation was attributed to dephosphorylation of the phosphorylated enzyme complex, and the total enzyme activity was not altered by muscle contractions. The activation of the enzyme complex occurred in the muscle of the electrically stimulated leg, but not in the muscle of the non-stimulated (control) leg, indicating that blood components are not involved in the mechanism of the enzyme activation in the muscle. Adenine nucleotides, branched-chain amino and 2-oxo acids and lactate in the muscle were determined as possible factors modulating the enzyme complex activity through inhibition of branched-chain 2-oxo acid dehydrogenase kinase activity. The profile of enzyme activation induced by muscle contractions was different from the alteration of the adenine nucleotide concentrations but was similar to the alteration of the concentrations of branched-chain amino and 2-oxo acids in the muscle. The lactate concentration in the stimulated muscle was elevated 3-5 fold during the contractions, indicating intracellular acidification. Previous studies have shown that the 2-oxo acid derived from leucine is a potent inhibitor of the kinase. These results suggest that intracellular branched-chain 2-oxo acids increased by muscle contractions accumulate in the mitochondria due to exercise-induced acidification of the muscle cell, resulting in activation of branched-chain 2-oxo acid dehydrogenase complex by inhibition of the kinase.

Original languageEnglish (US)
Pages (from-to)290-296
Number of pages7
JournalBBA - General Subjects
Volume1157
Issue number2
DOIs
StatePublished - Jun 11 1993

Keywords

  • Branched-chain 2-oxo acid dehyrogenase complex
  • Branched-chain 2-oxo acids
  • Branched-chain amino acid
  • Lactate
  • Muscle
  • Tetanic contraction

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Molecular Biology

Fingerprint Dive into the research topics of 'Branched-chain 2-oxo acid dehydrogenase complex activation by tetanic contractions in rat skeletal muscle'. Together they form a unique fingerprint.

  • Cite this