The redox state of the mitochondrial NAD system in cirrhosis of the liver and in chronic quantitative undernutrition in the rat

Abstract

1. 1. To determine the redox state of the mitochondrial NAD system in cirrhosis of the liver and in chronic quantitative undernutrition, the substrates of the l-glutamate dehydrogenase (EC 1.4.1.2) and d-β-hydroxybutyrate dehydrogenase (EC 1.1.1.30) reactions were measured. The livers of animals fed ad libitum served as controls. 2. 2. Assuming these substrates to be in equilibrium, the NAD +/NADH ratio calculated from the substrates of the l-glutamate dehydrogenase reaction was lower in all three groups of animals than that calculated from the d-β-hydroxybutyrate dehydrogenase reaction. On the other hand, the ratio ([β- hydroxybutyrate] × [α- ketoglutarate] × [ NH 4 +]) ([ acetoacetate] × [ glutamate]) was similar in all three groups of animals. 3. 3. These data suggest that in these animals the mitochondrial NAD +-NADH system is in equilibrium provided a H + concentration gradient can be postulated between the sites of d-β-hydroxybutyrate dehydrogenase and l-glutamate dehydrogenase.