PYRIDINE NUCLEOTIDES IN HUMAN ERYTHROCYTES IN DIFFERENT METABOLIC STATES

1. 1. NAD+, NADH, NADP+, and NADPH concentrations in intact erythrocytes 2. 2. When acid extracts were prepared in the presence of ascorbic acid, NADP+ was markedly lower as observed by Burch, Bradley and Lowry. An influence of this agent on NAD+ content was not readily apparent but was demonstrable under appropriate conditions. Accordingly, ascorbic acid treatment appears to be necessary in order to obtain valid figures for NAD+ as well as for NADP+. 3. 3. In incubation studies, NADP+ increased and both NADPH and NADH decreased when medium glucose was omitted. With 0.5 mM iodoacetate and 10 mM glucose, only a decrease in NADH was noted. Thus, glucose lack alters nucleotide concentrations associated with both glycolytic adn phosphogluconate pathways, whereas iodoacetate only modifies the reduced nucleotide level related to glycolysis. 4. 4. In contrast to glucose-free controls, 10 mM lactate increased NADPH as well as NADH levels. Both NADPH and NADH were decreased in the presence of 10 mM pyruvate and glucose. These findings suggest the presence of a transhydrogenase activity. 5. 5. Change in NAD+ was not generally observed except for the decrease noted with 5 mM fluoride. It appears that NAD+ content may be influenced by factors other than those affecting glycolysis directly. © 1969.