Zonation of alanine metabolism in the bivascularly perfused rat liver.
OBJECTIVE
Zonation of alanine metabolism was investigated in the bivascularly perfused rat liver, a technique in which a selective area of the periportal region can be reached via the hepatic artery.


METHODS
Bivascular liver perfusion was done in both the antegrade and retrograde modes. Predominance of a given metabolic parameter in the periportal or perivenous area was deduced from comparisons of the changes caused by alanine infusion into the hepatic artery in antegrade and retrograde perfusion.


RESULTS
Confirming previous notions, glutamine synthesis predominated in the perivenous area, however, the contribution of the periportal area was significant. Gluconeogenesis and the associated extra oxygen consumption were more pronounced in the periportal region. The capacity of urea synthesis in the periportal region was relatively small as indicated by the ratios of urea to glucose production, which were lower in this region. Ammonia in the periportal region was considerably above the mean ammonia production of whole the liver parenchyma. The overflows of pyruvate and lactate were considerably smaller in the periportal region.


CONCLUSIONS
The distribution of alanine metabolism seems to reflect mainly zonation of the fates of the carbon skeleton (mainly gluconeogenesis). The production of glutamine in the periportal area is in agreement with recent reports about the presence of glutamine synthetase in Kupffer and endothelial cells.
Laboratory of Liver Metabolism, University of Maringá, 87020900 Maringá, Brazil.
Fernanda Fonseca
FF
Botini
Fumie
F
Suzuki-Kemmelmeier
Ecio Alves
EA
Nascimento
Luci Tiemi
LT
Ide
Adelar
A
Bracht
D000409:Alanine / Q000378:metabolism*; D000818:Animals; D010478:Chemotherapy, Cancer, Regional Perfusion / Q000379:methods*; D005943:Gluconeogenesis / Q000502:physiology; D005947:Glucose / Q000378:metabolism; D006499:Hepatic Artery; D008099:Liver / Q000033:anatomy & histology* / Q000378:metabolism*; D008297:Male; D010101:Oxygen Consumption; D051381:Rats; D017208:Rats, Wistar
D005947:Glucose; D000409:Alanine