Systemic, cerebral and skeletal muscle ketone body and energy metabolism during acute hyper-D-β-hydroxybutyrataemia in post-absorptive healthy males

Context: Ketone bodies are substrates during fasting and when on a ketogenic diet not the least for the brain and implicated in the management of epileptic seizures and dementia. Moreover, D-β-hydroxybutyrate (HOB) is suggested to reduce blood glucose and fatty acids levels. Objectives: Quantitating systemic, cerebral and skeletal muscle HOB utilization and its effect on energy metabolism. Design: Single trial. Setting: Hospital. Participant: Healthy post-absorptive males (n=6). Interventions: Subjects were studied under basal condition and three consecutive 1 h periods with a 3-, 6- and 12-fold increased HOB concentration via HOB infusion. Main outcome measures: Systemic, cerebral and skeletal muscle HOB kinetics, oxidation, glucose turnover and lipolysis via arterial, jugular and femoral venous differences in combination with stable isotopically labelled HOB, glucose and glycerol infusion. Results: 1. An increase in HOB from the basal 160 to 450 μmol/L elicited 14±2% reduction (P=0.03) in glucose appearance and 37±4% decrease (P=0.03) in lipolytic rate while insulin and glucagon were unchanged; 2. Endogenous HOB appearance was reduced in a dose-dependent manner with complete inhibition at the highest HOB concentration (1.7 mmol/L); 3. Cerebral HOB uptake and subsequent oxidation was linearly related to the arterial HOB concentration; 4. Resting skeletal muscle HOB uptake showed saturation kinetics. Conclusion: A small increase in the HOB concentration decreases glucose production and lipolysis in post-absorptive healthy males. Moreover, cerebral HOB uptake and oxidation rates are linearly related to the arterial HOB concentration of importance for modifying brain energy utilization, potentially of relevance for patients with epileptic seizures and dementia.