AJP - Regulatory, Integrative and Comparative Physiology, Vol 256, Issue 4 907-R914, Copyright © 1989 by American Physiological Society
Gluconeogenesis in perfused livers from dexamethasone-treated chickens
T. Kobayashi, H. Iwai, R. Uchimoto, M. Ohta, M. Shiota and T. Sugano
Department of Veterinary Physiology, College of Agriculture, University of Osaka Prefecture, Japan.
Gluconeogenesis was studied in hemoglobin-free perfused livers from
chickens that had received daily injections of dexamethasone sulfate for 5
days. Dexamethasone increased to approximately 160% the level of plasma
glucose and doubled the content of hepatic glycogen in fed chickens. In the
isolated perfused livers from chickens starved for 48 h after the last
dexamethasone injection, the rates of production of glucose from lactate
decreased by approximately 30% and biphasic changes in glucose production
from fructose proceeded in parallel with biphasic changes in the production
of lactate and pyruvate. Quinolinate had no effect on gluconeogenesis in
both groups. NH4Cl markedly inhibited the production of glucose from
pyruvate-lactate mixtures in dexamethasone-treated chickens but stimulated
in controls. Aminooxyacetate reversed the effects of NH4Cl in
dexamethasone-treated chickens. The data presented provide evidence
indicating that the reaction of mitochondrial alanine aminotransferase
plays an important role in the regulation of the hepatic gluconeogenesis in
dexamethasone-treated chickens.
