Release of leucine and isoleucine metabolites by perfused skeletal muscle and liver of rat

Int J Biochem. 1983;15(8):985-90. doi: 10.1016/0020-711x(83)90033-2.


The oxidation of leucine, isoleucine and the corresponding 2-ketoacids was studied in perfused hindquarter and liver of rat. The metabolites from these compounds released into the perfusate were identified by anion exchange chromatography and gas chromatography/mass spectrometry. Muscle perfused in the presence of leucine accumulated ketoleucine (2-ketoisocaproate) and isovalerate, while perfusion with isoleucine resulted in ketoisoleucine (2-keto-3-methylvalerate) and 2-methylbutyrate. Octanoate stimulated the oxidation of the branched-chain amino acids. The fatty acid did not change the amount of branched-chain 2-keto acids released into the perfusate, but increased the output from the muscle of the oxidation products isovalerate (from leucine) and 2-methylbutyrate (from isoleucine). Rat liver perfused with ketoleucine released mainly ketone bodies and small quantities of 3-hydroxyisovalerate while ketoisoleucine resulted mainly in release of lactate and ketone bodies. Accumulation of metabolites from the branched-chain amino acids is discussed in relation to the metabolism of the amino acids in skeletal muscle and liver of rat.

MeSH terms

  • 3-Hydroxybutyric Acid
  • Acetoacetates / metabolism
  • Animals
  • Female
  • Hydroxybutyrates / metabolism
  • Isoleucine / metabolism*
  • Keto Acids / metabolism
  • Lactates / metabolism
  • Lactic Acid
  • Leucine / metabolism*
  • Liver / metabolism*
  • Muscles / metabolism*
  • Rats
  • Rats, Inbred Strains
  • Valerates / metabolism


  • Acetoacetates
  • Hydroxybutyrates
  • Keto Acids
  • Lactates
  • Valerates
  • Isoleucine
  • alpha-keto-beta-methylvaleric acid
  • Lactic Acid
  • beta-hydroxyisovaleric acid
  • alpha-ketoisocaproic acid
  • Leucine
  • 3-Hydroxybutyric Acid