[Some mechanisms of carbohydrate metabolism regulation with NADP participation]

It is shown that in the presence of NADP in the myocardium extracts glucose-6-phosphate is transformed into fructose-6-phosphate, fructose-1,6-diphosphate and lactate. The intensity of this transformation is close to that when NAD is introduced. The addition of crystalline glucose-6-phosphate dehydrogenase to the extracts is not accompanied by formation of lactate, but reduced NADP accumulates which oxidizes due to introduction of pyruvate or oxalacetate into the medium. This process is reconstructed in the system with pure enzymes (glucose-6-phosphate dehydrogenase, lactate dehydrogenase), that evidences for hydrogen transfer from reduced NADP to pyruvate, or to the oxalacetate without participation of transhydrogenase. The oxidation rate of the reduced coenzymes in the myocardium extracts depends on the medium pH: when pH increases, it lowers for NAD-H and rises for NAD-H. The NAD-H divided by NADP-H rate ratio at pH 7.0 for pyruvate is 11.5 and for oxalacetate is 6.5.