Nonhepatic glucose production in humans.
Extrahepatic glucose release was evaluated during the anhepatic phase of liver transplantation in 14 recipients for localized hepatocarcinoma with mild or absent cirrhosis, who received a bolus of [6,6-2H2]glucose and l-[3-13C]alanine or l-[1,2-13C2]glutamine to measure glucose kinetics and to prove whether gluconeogenesis occurred from alanine and glutamine. Twelve were studied again 7 mo thereafter along with seven healthy subjects. At the beginning of the anhepatic phase, plasma glucose was increased and then declined by 15%/h. The right kidney released glucose, with an arteriovenous gradient of -3.7 mg/dl. Arterial and portal glucose concentrations were similar. The glucose clearance was 25% reduced, but glucose uptake was similar to that of the control groups. Glucose production was 9.5 +/- 0.9 micromol.kg-1. min-1, 30% less than in controls. Glucose became enriched with 13C from alanine and especially glutamine, proving the extrahepatic gluconeogenesis. The gluconeogenic precursors alanine, glutamine, lactate, pyruvate, and glycerol, insulin, and the counterregulatory hormones epinephrine, cortisol, growth hormone, and glucagon were increased severalfold. Extrahepatic organs synthesize glucose at a rate similar to that of postabsorptive healthy subjects when hepatic production is absent, and gluconeogenic precursors and counterregulatory hormones are markedly increased. The kidney is the main, but possibly not the unique, source of extrahepatic glucose production.
Battezzati
Alberto
A
International Center for the Assessment of Nutritional Status, DiSTAM, University of Milan, 20133 Milan, Italy. battezzati.alberto@hsr.it
Caumo
Andrea
A
Martino
Francesca
F
Sereni
Lucia Piceni
LP
Coppa
Jorgelina
J
Romito
Raffaele
R
Ammatuna
Mario
M
Regalia
Enrico
E
Matthews
Dwight E
DE
Mazzaferro
Vincenzo
V
Luzi
Livio
L
D000328:Adult; D000409:Alanine / Q000378:metabolism; D001786:Blood Glucose / Q000378:metabolism*; D002277:Carcinoma / Q000601:surgery; D005500:Follow-Up Studies; D005943:Gluconeogenesis / Q000502:physiology*; D005973:Glutamine / Q000378:metabolism; D006498:Hepatectomy; D006801:Humans; D007668:Kidney / Q000378:metabolism*; D008099:Liver / Q000378:metabolism; D008113:Liver Neoplasms / Q000601:surgery; D016031:Liver Transplantation / Q000502:physiology; D008875:Middle Aged
D001786:Blood Glucose; D005973:Glutamine; D000409:Alanine