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Nonhepatic glucose production in humans
Alberto Battezzati1, Andrea Caumo, Francesca Martino
1International Center for the Assessment of Nutritional Status, DiSTAM, University of Milan, 20133 Milan, Italy. battezzati.alberto@hsr.it
Summary
During liver transplantation, extrahepatic organs like the kidney produce glucose when the liver is absent. This process, known as gluconeogenesis, is vital for maintaining blood glucose levels.
Area of Science:
- Metabolic research
- Physiology
- Transplantation science
Background:
- Liver transplantation necessitates understanding glucose metabolism during the anhepatic phase.
- Extrahepatic glucose production is crucial when hepatic function is absent.
Purpose of the Study:
- To quantify extrahepatic glucose release during the anhepatic phase of liver transplantation.
- To determine if gluconeogenesis occurs from alanine and glutamine in extrahepatic tissues.
- To compare glucose kinetics in recipients with healthy controls.
Main Methods:
- Administered stable isotopes ([6,6-2H2]glucose, l-[3-13C]alanine, l-[1,2-13C2]glutamine) to liver transplant recipients.
- Measured glucose kinetics, arteriovenous gradients, and isotope enrichment.
- Compared data from the anhepatic phase, post-transplant, and healthy subjects.
Main Results:
- The kidney was identified as a significant source of glucose release during the anhepatic phase.
- Extrahepatic gluconeogenesis from alanine and glutamine was confirmed.
- Despite reduced hepatic production, extrahepatic glucose production compensated, with elevated precursors and hormones.
Conclusions:
- Extrahepatic organs maintain glucose homeostasis in the absence of the liver.
- The kidney plays a primary role in extrahepatic glucose production.
- Gluconeogenesis from amino acids is a key compensatory mechanism.