The effect of phenylhydrazine on the adenosine triphosphate content of normal and glucose-6-phosphate dehydrogenase-deficient human blood

Effect of phenylhydrazine on red blood cell metabolism

In addition to the well known effect of phenylhydrazine on red blood cells (methaemoglobin and Heinz body formation, autologous IgG binding, lipid peroxidation, etc.) an increased glucose utilization was observed. Measurement of 14CO2 formation from [1-14C]-glucose showed a maximum value at 2mM phenylhydrazine followed by a progressive inhibition on increasing the drug concentration to 16 mM. Concomitantly we found a reduction in the reduced glutathione concentration but not a corresponding increase in the level of oxidized glutathione. Phenylhydrazine also causes ATP depletion. The ATP is in part dephosphorylated to ADP and AMP and in part converted to inosine monophosphate and hypoxanthine. Measurement of the cell content of reduced and oxidized pyridine nucleotides was also performed and showed a progressive increase in the reduced forms of these coenzymes. Thus phenylhydrazine promotes cellular ATP depletion followed by adenine nucleotide catabolism that is not efficiently counteracted by an increase in glucose utilization. The relevance of these data to the mechanism of phenylhydrazine-induced anemia is discussed.

Red blood cell phagocytosis and lysis following oxidative damage by phenylhydrazine

Red blood cells exposed in vitro to phenylhydrazine acquired Heinz bodies, bound autologous IgG and were then phagocytized when incubated with autologus mononuclear phagocytes. In vivo, phenylhdyrazine administered to rabbits, caused the appearance of high plasma hemoglobin levels and hemoglobinuria as well as Heinz body formations and IgG binding to erythrocytes. This suggests that while in vitro the main mechanism of red cell removal seems to be phagocytoses, in vivo both intravascular hemolysis and phagocytosis are active processes. Preliminary biochemical studies on phenylhydrazine-exposed erythrocytes showed that together with the well-known appearance of Heinz bodies, methemoglobin and a drop in reduced glutathione, this drug also causes ATP depletion. This is initially concomitant with the appearance of ADP and AMP and subsequently hypoxantine. Thus, irreversible ATP depletion may contribute to the genesis of the hemolytic process observed in vivo.

Congenital non-spherocytic hemolytic anemia

A family with congenital non-spherocytic hemolytic anemia associated with glucose-6-phosphate dehydrogenase (G6PD) deficiency was studied. Two females, heterozygous for the enzyme deficency, had evidence of a hemolytic anemia. The results of chromium-51 erythrocyte life span studies prior to, during, and after periods of primaquine administration suggested that the hemolytic anemia in these women was due to the presence of two populations of red blood cells in their circulation. One population had normal G6PD levels and a normal life span, whereas the other had diminished enzyme activity and a shortened life span.In vitro metabolic studies of the erythrocytes of a heterozygous female and a hemizygous male suggested that, in spite of G6PD deficiency, the synthesis and breakdown of adenosine triphosphate and 2,3-diphosphoglyceric acid was similar to that in normal erythrocytes.