title: Release of leucine and isoleucine metabolites by perfused skeletal muscle and liver of rat.
abstract: 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: D020155:3-Hydroxybutyric Acid; D000090:Acetoacetates / Q000378:metabolism; D000818:Animals; D005260:Female; D006885:Hydroxybutyrates / Q000378:metabolism; D007532:Isoleucine / Q000378:metabolism*; D007651:Keto Acids / Q000378:metabolism; D007773:Lactates / Q000378:metabolism; D019344:Lactic Acid; D007930:Leucine / Q000378:metabolism*; D008099:Liver / Q000378:metabolism*; D009132:Muscles / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D014631:Valerates / Q000378:metabolism
chemical_list: D000090:Acetoacetates; D006885:Hydroxybutyrates; D007651:Keto Acids; D007773:Lactates; D014631:Valerates; D007532:Isoleucine; C016211:alpha-keto-beta-methylvaleric acid; D019344:Lactic Acid; C004961:beta-hydroxyisovaleric acid; C013082:alpha-ketoisocaproic acid; D007930:Leucine; D020155:3-Hydroxybutyric Acid