Quantification of hepatic carbohydrate metabolism in conscious mice using serial blood and urine spots.
In vivo studies of hepatic carbohydrate metabolism in (genetically modified) conscious mice are hampered by limitations of blood and urine sample sizes. We developed and validated methods to quantify stable isotope dilution and incorporation in small blood and urine samples spotted onto filter paper. Blood glucose and urinary paracetamol-glucuronic acid were extracted from filter paper spots reproducibly and with high yield. Fractional isotopomer distributions of glucose and paracetamol-glucuronic acid when extracted from filter paper spots were almost identical to those isolated from the original body fluids. Rates of infusion of labeled compounds could be adjusted without perturbing hepatic glucose metabolism. This approach was used in mice to find the optimal metabolic condition for the study of hepatic carbohydrate metabolism. In fed mice, no isotopic steady state was observed during a 6-h label-infusion experiment. In 9-h-fasted mice, isotopic steady state was reached after 3 h of label infusion and important parameters in hepatic glucose metabolism could be calculated. The rate of de novo glucose-6-phosphate synthesis was 143 +/- 17 micromol kg(-1) min(-1) and partitioning to plasma glucose was 79.0 +/- 5.2%. In 24-h-fasted mice, abrupt changes were noticed in whole body and in hepatic glucose metabolism at the end of the experiment.
van Dijk
Theo H
TH
Laboratory of Pediatrics, Center for Liver, Digestive and Metabolic Diseases, University Hospital Groningen, P.O. Box 30.001, 9700 RB Groningen, The Netherlands. t.h.v.dijk@bkk.azg.nl
Boer
Theo S
TS
Havinga
Rick
R
Stellaard
Frans
F
Kuipers
Folkert
F
Reijngoud
Dirk-Jan
DJ
D000082:Acetaminophen / Q000493:pharmacokinetics*; D018712:Analgesics, Non-Narcotic / Q000493:pharmacokinetics; D000818:Animals; D001786:Blood Glucose / Q000032:analysis*; D001800:Blood Specimen Collection; D002247:Carbon Isotopes; D002849:Chromatography, Gas; D005215:Fasting / Q000378:metabolism; D005943:Gluconeogenesis / Q000502:physiology; D019298:Glucose-6-Phosphate / Q000096:biosynthesis; D020723:Glucuronic Acid / Q000652:urine*; D007201:Indicator Dilution Techniques; D008099:Liver / Q000378:metabolism*; D051379:Mice; D051381:Rats
D018712:Analgesics, Non-Narcotic; D001786:Blood Glucose; D002247:Carbon Isotopes; D000082:Acetaminophen; D019298:Glucose-6-Phosphate; D020723:Glucuronic Acid