Failure of infused beta-hydroxybutyrate to decrease proteolysis in man.
Ketone bodies have been suggested to have a protein-sparing effect, since infusion of Na-beta-hydroxybutyrate in man decreases plasma alanine concentrations and urinary nitrogen (N) excretion. To test this hypothesis, six normal postabsorptive volunteers were infused with Na-beta-hydroxybutyrate for 3 h. Rates of glucose, leucine carbon, and alanine appearance and disappearance from the plasma space were traced with [3-3H]glucose, L-[6,6,6-2H3]leucine, and [2,3,3,3-2H4]alanine. Rates of leucine N appearance and disappearance and the rate of transfer of leucine N to alanine were assessed with [15N]leucine. During ketone body infusion, plasma alanine decreased (P less than 0.05), whereas plasma leucine increased (P less than 0.05). Rates of alanine appearance increased (5.3 +/- 0.3 to 7.8 +/- 0.6 mumol/kg X min), but the increase in its rate of disappearance was slightly greater, accounting for the decrease in plasma alanine concentration. Leucine N flux and the rate and percent of leucine N transferred to alanine increased, whereas leucine carbon flux was unchanged. To determine the effect of the alkalemia induced by Na-beta-hydroxybutyrate, four additional subjects were infused with NaHCO3. Alkalemia had no effect on leucine N or carbon flux or on the rate of appearance of alanine, but increased the rate of alanine disappearance, resulting in a decrease in the plasma alanine concentration. Since the rate of appearance of leucine carbon was unaltered during the infusion of Na-beta-hydroxybutyrate, it is unlikely that hyperketonemia per se decreases proteolysis in postabsorptive man.
D020155:3-Hydroxybutyric Acid; D000293:Adolescent; D000328:Adult; D000409:Alanine / Q000097:blood; D000818:Animals; D001639:Bicarbonates / Q000494:pharmacology; D001786:Blood Glucose / Q000378:metabolism; D001798:Blood Proteins / Q000378:metabolism*; D004285:Dogs; D005260:Female; D005934:Glucagon / Q000097:blood; D006801:Humans; D006863:Hydrogen-Ion Concentration; D006885:Hydroxybutyrates / Q000378:metabolism / Q000494:pharmacology*; D007328:Insulin / Q000097:blood; D007657:Ketone Bodies / Q000097:blood; D007700:Kinetics; D007930:Leucine / Q000097:blood; D008297:Male; D017693:Sodium Bicarbonate
D001639:Bicarbonates; D001786:Blood Glucose; D001798:Blood Proteins; D006885:Hydroxybutyrates; D007328:Insulin; D007657:Ketone Bodies; D017693:Sodium Bicarbonate; D005934:Glucagon; D007930:Leucine; D000409:Alanine; D020155:3-Hydroxybutyric Acid