Validation of a tracer technique to determine nonsteady-state ketone body turnover rates in man
The features of a single-compartment model of total ketone bodies were evaluated using primed constant infusions of (3-14C)acetoacetate (AcAc) and of D-(3-14C)beta-hydroxybutyrate (beta OHB) in 12 postabsorptive subjects. The volume of distribution (VD) of AcAc was 0.18 +- 0.01 liter/kg (n = 9), and that of beta OHB was similar, 0.18 +- 0.02 liter/kg (n = 3). The production rate of total ketone bodies was calculated using the combined specific activity of AcAc and of beta OHB. The mean basal total ketone body production rates were similar using either (14C)AcAc (6.5 mumol . kg-1 . min-1) or (14C)beta OHB (6.8 mumol . kg-1 . min-1). To determine the pool fraction that was rapidly mixed during nonsteady state of ketone body inflow, unlabeled AcAc was infused with stepwise increasing and decreasing rates between 5 and 25 mumol . kg-1 . m-1 to mimic nonsteady-state ketone body production rates. The functional pool fraction P was determined as the pool fraction that provided the best match between tracer-determined rates of ketone production and rates of AcAc infusion. P of total ketone bodies was almost equal to 1 using either (14C)AcAc (1.05 +- 0.16) or (14C)beta OHB (1.00 +- 0.06), suggesting rapid mixing of ketone bodies throughout the entire pool. The described pool model may be used to determine total ketone body kinetics during acute perturbations of the steady state.
- OSTI ID:
- 5927482
- Journal Information:
- Am. J. Physiol.; (United States), Journal Name: Am. J. Physiol.; (United States) Vol. 240:3; ISSN AJPHA
- Country of Publication:
- United States
- Language:
- English
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550501 -- Metabolism-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ANIMALS
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL MODELS
BIOLOGICAL PATHWAYS
CARBON 14 COMPOUNDS
ISOTOPE APPLICATIONS
KETONES
KINETICS
LABELLED COMPOUNDS
MAMMALS
MAN
METABOLISM
ORGANIC COMPOUNDS
PRIMATES
REACTION KINETICS
VERTEBRATES