Effects of nutrition and ontogeny on liver cytosolic and mitochondrial phosphoenolpyruvate carboxykinase activity of the rat, hamster, guinea-pig, pig, kid, calf and chick.

In rat, hamster, guinea-pig, pig, kid, and calf liver, starvation or carbohydrate starvation increased cytosolic phosphoenolpyruvate carboxykinase activity without changing the mitochondrial activity whereas in chick liver, starvation did not alter the activity in both fractions. Liver glycogen content changed in a reciprocal way to the cytosolic phosphoenolpyruvate carboxykinase activity. In prenatal kid and chick liver, phosphoenolpyruvate carboxykinase activity appeared in both cytosolic and mitochondrial fractions, and in chick liver, considerable increase of the cytosolic activity was observed from a few days before hatching to 4 days after hatching.