The influence of rare earths on hepatic gluconeogenesis.

Abstract

After intravenous application of praseodymium nitrate, female Wistar rats develop a pronounced hypoglycemia which is due to an inhibition of hepatic gluconeogenesis. The renal gluconeogenesis remains uninfluenced. Among the gluconeogenetic key enzymes, pyruvate carboxylase and phosphoenolpyruvate carboxykinase are most drastically reduced in their activity, while there is only a slight effect on glucose-6-phosphatase and fructose-1,6-diphosphatase. An allosteric effect of praseodymium or a synthesis of an inhibitor caused by rare earths can be excluded. The activity of other enzymes which catalyse steps of both glycolysis and gluconeogenesis is not influenced. This selectivity of rare earths seems to indicate that there might be different genes for glycolysis and gluconeogenesis and led us to suppose that the site of action of rare earths is to be looked for at the nucleic acid system.