Gluconeogenesis in kidney cortex slices of the guinea pig. Its relation to acidosis and to calcium.

In contrast to rat kidney cortex the glucogenic capacity of kidney cortex slices from normally treated guinea pigs was very low. Reduction of the pH of the incubation medium by either lowering the HCO3-concentration or by increasing the pCO2 resulted only in varying stimulatory effects on glucose production from endogeneous or exogeneous sources. Considerable rates of net synthesis of glucose from lactate, pyruvate, malate, 2-oxoglutarate, glutamate, and glycerol--but not from glutamine--were only observed in kidneys from animals with prolonged metabolic acidosis. Neither in experiments with normally treated animals nor in those with acidotic guinea pigs the glucose production decreased, when calcium was omitted from the incubation medium. Though glutamine was not converted into glucose, it served as a substrate for ammoniagenesis. On the basis of the presented results it is concluded that species differences exist in the regulation of renal gluconeogenesis.