NADP+ and NADPH in glucose-6-phosphate dehydrogenase-deficient erythrocytes under oxidative stimulation

A mild oxidative stimulation of the hexose monophosphate pathway of human glucose-6-phosphate dehydrogenase (EC 1.1.1.49)-deficient erythrocytes (Mediterranean variant) causes a significant drop in NADPH. These results, other than to confirm that glucose-6-phosphate dehydrogenase deficiency is a product deficiency disorder, demonstrate that under oxidative stimulation glutathione reductase may become functionally impaired and GSSG cannot be reduced at a sufficient rate.

Erythrocyte metabolism in normal and glutathione-deficient sheep

Glucose utilization and lactate formation in erythrocytes from normal and glutathione (GSH)-deficient sheep were similar. Significant differences were observed, however, between the 2 groups of sheep in the production of 14-CO2 from erythrocytes incubated with ascorbic acid or methylene blue, or both. The greater response of normal erythrocytes compared to erythrocytes deficient in GSH suggests that there are some metabolic differences in the pentose phosphate pathway (ppp) activity of the erythrocytes. The nature and site of these differences are, however, not known. When sheep were kept in a decompression chamber for 2 weeks and subjected to a simulated altitude of 7,000 m for 12 hours/day, the erythrocytes showed a four- to six-fold increase in the activity of the ppp.

Red cell NADP+ and NADPH in glucose-6-phosphate dehydrogenase deficiency

Extraction in the presence of sodium hydroxide and cysteine allows estimates of NADPH and total NADP in human red cells without the erroneously high values of NADP+ obtained with earlier methods. An application of this technique to G6PD-deficient cells reveals that most of the nucleotide is in the oxidized form. In contrast, normal red cells have nearly all of the nucleotide in the reudced form. In addition to providing information concerning the intracellular regulation of the hexose monophosphate shunt, these findings support the concept that G6PD deficiency is a product-deficiency disorder.

Glucose-6-phosphate dehydrogenase in the blood of psoriatics, and the effects of methotrexate

The kinetic constants of glucose-6-phosphate dehydrogenase from the blood of psoriatics with and without methotrexate therapy have been determined. The constants were also determined in the blood of normal subjects and subjects suffering from atopic dermatitis and mycosis fungoides. No significant differences were found between subjects not receiving methotrexate. The subjects receiving methotrexate showed markedly increased Km values for both glucose-6-phosphate and NADP under the conditions used. The results are discussed in relation to psoriasis and its therapy.