Ketone bodies inhibit leucine degradation in chick skeletal muscle.
Level 5 - mechanism / opinion, no new human data
Oxford CEBM Level 5: bench/animal ex vivo tissue study with no human data.
PubMed 3666283 · doi:10.1016/0020-711x(87)90175-3
What was done
Researchers incubated isolated extensor digitorum communis muscles from fed and 24-hour fasted chicks with DL-beta-hydroxybutyrate (1 and 4 mM) or acetoacetate (1 and 4 mM) and measured net rates of leucine transamination, 2-oxoisocaproate (KIC) production, leucine oxidative decarboxylation, and total leucine oxidation.
What was found
In fed chick muscle, 4 mM DL-beta-hydroxybutyrate increased net leucine transamination and net KIC production, whereas 1 and 4 mM DL-beta-hydroxybutyrate inhibited leucine oxidative decarboxylation. Acetoacetate (1 and 4 mM) increased net KIC production while inhibiting leucine oxidative decarboxylation and total leucine oxidation. In 24-hour fasted chick muscle, both DL-beta-hydroxybutyrate and acetoacetate at 1 and 4 mM inhibited net leucine transamination, leucine oxidative decarboxylation, and total leucine oxidation. The abstract reports no numerical values, variances, or p-values.
Why it matters
This study provides bench-level biochemical evidence that ketone bodies directly suppress the catabolic oxidation of leucine in avian skeletal muscle.
Limits
The experiment was conducted ex vivo on isolated avian muscle tissue and cannot directly establish human metabolic effects. No sample sizes, baseline values, or quantitative effect sizes are provided in the abstract.
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