Age-dependent changes of hormone-stimulated gluconeogenesis in isolated rat hepatocytes.

Effects of glucagon or catecholamine stimulation on glucose synthesis from lactate/pyruvate, alanine, fructose or glycerol in isolated hepatocytes from young and old rats were compared. It was found that production of glucose by non-stimulated hepatocytes was almost the same in hepatocytes both from young and old rats. The concentrations of hormones which caused the maximal effect were the same for both compared groups of rats. However, the effect of stimulation by glucagon was significantly greater in hepatocytes of young rats than of old ones, when lactate/pyruvate or alanine were used as substrates, while no such difference was observed when fructose or glycerol were used. Epinephrine and norepinephrine stimulated glucose synthesis from all substrates investigated to the same extent in hepatocytes isolated from both compared groups of rats. The biochemical and physiological aspects of these findings are discussed.