Evolution of the content of gluconeogenic metabolites in rat liver and kidney during exercise

Abstract

The evolving concentration of metabolite intermediates for gluconeogenesis in liver and kidney has been studied in rats after varying periods of exercise (swimming in water at 22 degrees C).Lactate consumption by liver, according to the results, does not take place by gluconeogenesis primarily, since the values for malate, aspartate and PEP show a low in vivo activity for phosphoenolpyruvate carboxykinase.The PEP/aspartate ratio, on the contrary, gradually rises in kidney, suggesting a gradual increase in the in vivo activity of phosphoenolpyruvate carboxykinase, which agree quite well with the results of previously obtained in vitro.The prevention of metabolic acidosis by bicarbonate administration affects the metabolite profile in liver during exercise only very slightly.Renal phosphoenol-pyruvate carboxykinase activity in vivo decreases in relation to previously untreated rats, as well as gluconeogenesis, although to a lesser extent.