Cultured rat hepatocytes adapt their cellular glycolytic activity and adenylate energy status to tissue oxygen tension: influences of extracellular matrix components, insulin and glucagon.
The influence of extracellular matrix components, insulin, and glucagon on the cellular response to periportal- or pericentral-equivalent tissue oxygen tension was investigated in freshly isolated rat hepatocytes cultured at 13% O2 or 4% O2 in Teflon membrane dishes. With extended culture time, significant increases in lactate release and cellular lactate content were observed in cultures at 4% O2 compared with 13% O2. This shift toward glycolysis was detectable when hepatocytes were cultured on dishes coated with rat liver crude membrane fraction (CMF/COL) but not in collagen type I-coated dishes. This indicates that extracellular matrix components are involved in the process of adaptation. ATP and total adenylate content in cells cultured at 4% O2 were up to 40% lower than in cells cultured at 13% O2. However, the adenylate energy charge was not affected, suggesting that an adequate energy supply was maintained also in hepatocytes cultured at pericentral-equivalent oxygen tension. This adaptation was reversible. When hepatocytes were transferred either from 4% to 13% O2 or from 13% to 4% O2, they adapted the corresponding metabolic profile to the new oxygen tension within 2 days. This demonstrates that hepatocytes are not fully unidirectionally programmed. The modulation of the glycolytic activity by insulin and glucagon was effective in cultures at pericentral-equivalent oxygen tension (4% O2) only. Insulin (0.1-100 nM) shifted cellular metabolism toward the glycolytic pathway and glucagon (1-100 nM) counteracted the effect of insulin in a dose-dependent manner. Clearly, oxygen tension is the principal regulator in the hepatic glycolytic activity, whereas the hormones (insulin and glucagon) act as secondary modulators.
Ohno
K
K
Institute of Toxicology, Swiss Federal Institute of Technology, Schwerzenbach.
Maier
P
P
D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D002478:Cells, Cultured; D004734:Energy Metabolism; D005109:Extracellular Matrix / Q000378:metabolism*; D005934:Glucagon / Q000378:metabolism*; D006019:Glycolysis; D007328:Insulin / Q000378:metabolism*; D008099:Liver / Q000166:cytology / Q000378:metabolism*; D008297:Male; D009928:Organ Specificity; D010100:Oxygen / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley
D007328:Insulin; D000255:Adenosine Triphosphate; D005934:Glucagon; D010100:Oxygen