Partial oxidation of leucine in skeletal muscle.
1. Leucine and its 2-oxo analogue, 4-methyl-2-oxopentanoate, increased the release of acetoacetate and 3-hydroxybutyrate from hemidiaphragms isolated from 40 h-starved rats. Glucose and lactate+pyruvate decreased basal and leucine-stimulated rates of ketone body production. 2. The production of acetoacetate + 3-hydroxybutyrate in response to addition of leucine was suppressed in hemidiaphragms from fed rats. 3. At 3 mM leucine, for each mumol of leucine oxidized in the branched-chain 2-oxo acid dehydrogenase reaction (measured as 14CO2 production from [1-14C]leucine), 0.84 mumol of acetoacetate + 3-hydroxybutyrate were produced. This stoichiometry may imply that acetoacetate derived from the partial oxidation of leucine is not further oxidized in situ. The physiological significance of these findings is discussed.
Department of Biochemistry, University of Western Australia, Nedlands.
T N
TN
Palmer
S
S
Gossain
M C
MC
Sugden
D020155:3-Hydroxybutyric Acid; D000090:Acetoacetates / Q000378:metabolism; D000818:Animals; D003964:Diaphragm; D004435:Eating; D005947:Glucose / Q000494:pharmacology; D006885:Hydroxybutyrates / Q000378:metabolism; D007651:Keto Acids / Q000378:metabolism*; D007657:Ketone Bodies / Q000378:metabolism*; D007773:Lactates / Q000494:pharmacology; D019344:Lactic Acid; D007930:Leucine / Q000378:metabolism*; D008297:Male; D009132:Muscles / Q000378:metabolism*; D010084:Oxidation-Reduction; D011773:Pyruvates / Q000494:pharmacology; D019289:Pyruvic Acid; D051381:Rats; D017208:Rats, Wistar
D000090:Acetoacetates; D006885:Hydroxybutyrates; D007651:Keto Acids; D007657:Ketone Bodies; D007773:Lactates; D011773:Pyruvates; D019344:Lactic Acid; C016635:acetoacetic acid; C013082:alpha-ketoisocaproic acid; D019289:Pyruvic Acid; D007930:Leucine; D005947:Glucose; D020155:3-Hydroxybutyric Acid