The development of gluconeogenesis in rat liver. Effects of glucagon and ether.
1. Administration of glucagon to foetal rats produced a 10-15-fold increase in hepatic phosphoenolpyruvate carboxykinase activity together with a similar increase in the overall pathway of pyruvate conversion into glycogen in liver slices. 2. Glucagon was without effect on gluconeogenesis in vivo, which remained at approx. 0.1% of the incorporation as measured in newborn animals. 3. The apparent discrepancy between these results was due to the ether anaesthesia that was required for experimentation in vivo. Under conditions when minimal ether was used, the rates of labelling of glycogen from [3-(14)C]pyruvate in vivo were increased 10-20-fold and there was an additional stimulus by glucagon. 4. Ether anaesthesia produced a more reduced redox state of the foetal liver cytosol and lowered the ATP/ADP concentration ratio. 5. It is proposed that these effects are significant in the limitation of gluconeogenesis in the foetal rat liver, so that only with high phosphoenolpyruvate carboxykinase activity, high ATP concentration and a relatively oxidized cytosol redox state will a functional gluconeogenic pathway be present.
D000227:Adenine Nucleotides / Q000032:analysis; D000255:Adenosine Triphosphate / Q000032:analysis; D000758:Anesthesia; D000818:Animals; D000831:Animals, Newborn; D002247:Carbon Isotopes; D005019:Ethyl Ethers / Q000494:pharmacology*; D005333:Fetus; D005934:Glucagon / Q000494:pharmacology*; D005943:Gluconeogenesis / Q000187:drug effects*; D066298:In Vitro Techniques; D008099:Liver / Q000187:drug effects* / Q000201:enzymology; D008112:Liver Glycogen / Q000096:biosynthesis; D010084:Oxidation-Reduction; D010101:Oxygen Consumption; D011770:Pyruvate Kinase / Q000378:metabolism; D011773:Pyruvates / Q000378:metabolism; D051381:Rats
D000227:Adenine Nucleotides; D002247:Carbon Isotopes; D005019:Ethyl Ethers; D008112:Liver Glycogen; D011773:Pyruvates; D000255:Adenosine Triphosphate; D005934:Glucagon; D011770:Pyruvate Kinase