Renal phosphoenolpyruvate carboxykinase during perturbations of acid-base homeostasis in rats. Immunochemical studies.

The activity of phosphoenolpyruvate carboxykinase (PEPCK) increased in the rat kidney after induction of metabolic acidosis. Immunotitration of the enzyme in renal extracts from normal and acidotic rats indicate that this increase in catalytic activity correlates with the amount of immunotitrateable activity. PEPCK activity decreased rapidly during recovery from acidosis and the time required for the activity to return to normal was not altered by the administration of NaHCO3 at the start of recovery. Immunotitration of the enzyme from rats allowed to recover from metabolic acidosis revealed that the decrease in catalytic activity was paralleled by a decrease in the amount of immunotitrateable activity. It is concluded that the rise and fall in PEPCK activity during acidosis and recovery from acidosis, respectively, are due to comparable changes in enzyme protein.