Hepatic uptake and metabolism of galactose can be quantified in vivo by 2-[18F]Fluoro-2-deoxy-galactose Positron Emission Tomography.

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  • The Department of Surgical Gastroenterology L
  • The Department of Hepatology and Gastroenterology V
  • Positron Emission Tomography Center
Metabolism of galactose is a specialized liver function. The purpose of this PET study was to use the galactose analog 2-[(18)F]fluoro-2-deoxy-galactose, FDGal, to investigate hepatic uptake and metabolism of galactose in vivo. FDGal kinetics was studied in 10 anaesthetized pigs at blood concentrations of non-radioactive galactose yielding approx. first-order kinetics (tracer only; n=4), intermediate kinetics (0.5 - 0.6 mmol galactose/L blood; n=2), and near-saturation kinetics (>3 mmol galactose/L blood; n=4). All animals underwent liver C(15)O PET (blood volume) and FDGal PET (galactose kinetics) with arterial and portal venous blood sampling. Flow rates in the hepatic artery and the portal vein were measured by ultrasound transit-time flow-meters. The hepatic uptake and net metabolic clearance of FDGal were quantified by non-linear and linear regression analyses. The initial extraction fraction of FDGal from blood-to-hepatocyte was unity in all pigs. Hepatic net metabolic clearance of FDGal, K(FDGal), was 332 - 455 mL blood/min/L tissue in experiments with approx. first-order kinetics and 15.2 - 21.8 mL blood/min/L tissue in experiments with near-saturation kinetics. Maximal hepatic removal rates of galactose was on average 600 micromol/min/L tissue (range 412 - 702) which was in agreement with other studies. There was no significant difference between K(FDGal) calculated using the dual tracer input or using the single arterial input. In conclusion, hepatic galactose kinetics can be quantified with the galactose analog FDGal. At near-saturated kinetics, the maximal hepatic removal rate of galactose can be calculated from the net metabolic clearance of FDGal and the arterial blood concentration of galactose. Key words: Liver physiology, Michaelis-Menten kinetics, Liver function, Clearance, Galactokinase.
Original languageEnglish
JournalAmerican Journal of Physiology: Gastrointestinal and Liver Physiology
ISSN0193-1857
DOIs
Publication statusPublished - 2008

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