Effect of starvation on renal metabolism in the rat

The effects of starvation on the acid-base status of the rat and on the glucoeogenic and ammoniagenic capacity of rat renal-cortical slices were examined. Starvation for 48 or 72 hr did not affect acid-base status, and urinary ammonia production did not change. Kidney cortical slices from starved as compared to fed rats showed increased gluconeogenic capacity when incubated with the substrated pyruvate, succinate, fumarate, malate, 2-oxyoglutarate, glutamine and glutamate. Renal cortical tissue from starved rats also had increased activity of the gluconeogenic enzyme phosphoenolpyruvate carboxykinase. Renal cortical slices from starved rats did not differ from those from fed rats in the ability to produce ammonia from glutamine or glutamate, nor was there any difference inhe activity of glutaminase between these groups. These results show that renal gluconeogenic capacity is increased in starved rats in the absence of systemic acidosis, and starvation does not lead to an increase in urinary ammonia excretion or renal ammoniagenic capacity.