European journal of clinical investigation · 1998
Measurement of free fatty acid kinetics during non-equilibrium tracer conditions in man: implications for the estimation of the rate of appearance of free fatty acids.
Клиническое исследованиеСравнительное исследованиеКонтролируемое клиническое исследованиеСтатьяПоддержка исследования: вне правительства СШАНазвание и аннотация: Перевод в очереди
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Riemens S C, Dullaart R P, Franssen E J, Piers D A, Reitsma W D, Sluiter W J
Аннотация
BACKGROUND: This study aimed to document the applicability and variability of free fatty acid (FFA) kinetic parameters during non-equilibrium and equilibrium tracer conditions in man.
METHODS: FFA kinetic parameters were assessed after an overnight fast in six healthy non-obese and three obese subjects as well as in three patients with non-insulin-dependent diabetes mellitus (NIDDM) by infusion of [14C]-palmitate of 60 min (study A) and 10 min duration (study B).
RESULTS: The kinetic parameters estimated from the upstroke and downstroke of the plasma FFA specific activity curve (non-equilibrium) were not statistically different within studies A and B. Furthermore, there were no significant differences in any of the FFA kinetic parameters between studies A and B. The averaged plasma levels of FFA obtained during the up- and downstroke from studies A and B were higher in obese subjects and NIDDM patients than in non-obese subjects (P < 0.01). The averaged total rate of appearance (TRa) of FFA was higher in obese subjects than in non-obese subjects (P < 0.02). The TRa and metabolic clearance rate (MCR), estimated from non-equilibrium conditions, were about 25% higher than the apparent values obtained from steady-state measurement in all subjects combined (P < 0.01), suggesting considerable recirculation of label from hydrolysis of labelled esterified fatty acids. Indeed, in three non-obese subjects, the radiolabel in esterified fatty acids was approximately 50% of labelled FFA at 60 min of label infusion. The coefficients of variation of the kinetic parameters were consistently larger in study A than in study B.
CONCLUSION: FFA kinetic parameters can be estimated with sufficient precision using non-equilibrium data from short-term labelled palmitate infusion. Short-term label infusion has the advantage that label recirculation is prevented and exposure to radiation is limited.
METHODS: FFA kinetic parameters were assessed after an overnight fast in six healthy non-obese and three obese subjects as well as in three patients with non-insulin-dependent diabetes mellitus (NIDDM) by infusion of [14C]-palmitate of 60 min (study A) and 10 min duration (study B).
RESULTS: The kinetic parameters estimated from the upstroke and downstroke of the plasma FFA specific activity curve (non-equilibrium) were not statistically different within studies A and B. Furthermore, there were no significant differences in any of the FFA kinetic parameters between studies A and B. The averaged plasma levels of FFA obtained during the up- and downstroke from studies A and B were higher in obese subjects and NIDDM patients than in non-obese subjects (P < 0.01). The averaged total rate of appearance (TRa) of FFA was higher in obese subjects than in non-obese subjects (P < 0.02). The TRa and metabolic clearance rate (MCR), estimated from non-equilibrium conditions, were about 25% higher than the apparent values obtained from steady-state measurement in all subjects combined (P < 0.01), suggesting considerable recirculation of label from hydrolysis of labelled esterified fatty acids. Indeed, in three non-obese subjects, the radiolabel in esterified fatty acids was approximately 50% of labelled FFA at 60 min of label infusion. The coefficients of variation of the kinetic parameters were consistently larger in study A than in study B.
CONCLUSION: FFA kinetic parameters can be estimated with sufficient precision using non-equilibrium data from short-term labelled palmitate infusion. Short-term label infusion has the advantage that label recirculation is prevented and exposure to radiation is limited.