High glucose concentration and phosphoenolpyruvate carboxykinase activity in human and rat fetal liver cultures.

In cultures of human and rat fetal liver, phosphoenolpyruvate carboxykinase activity increases during the first 24 hr of culturing. This increase can be suppressed by adding cycloheximide to the culture medium or by adding a high glucose concentration. This, however, applies only to human fetal liver and to fetal liver from rats obtained just before term. In younger rat fetal liver, glucose, on the contrary, increases the activity of phosphoenolpyruvate carboxykinase. A high glucose concentration in the medium also leads to higher citrate cleavage enzyme activity and to lower alpha-glycerolphosphate dehydrogenase (cytoplasmic) activity in rat fetal liver cultures.