Methemoglobin reductase system

Methemoglobinemia Intake of excess oxidants (various chemicals and drugs) Genetic deficiency in the NADH-dependent methemoglobin reductase system (MIM 250800) Inheritance of HbM (MIM 141800)... 

The iron of Hb must be maintained in the ferrous state ferric iron is reduced to the ferrous state by the action of an NADH-dependent methemoglobin reductase system involving cytochrome reductase and cytochrome b. ... 

E. The Functional Methemoglobin Reductase System OP THE Mature Erythrocyte... 

Methemoglobinemia has long been associated with the absence of an NADH-linked diaphorase 362, 363). However, flavoproteins isolated from the red cell were never sufficiently active to account for the methemoglobin reductase activity calculated to be necessary. It has now been shown that a methemoglobin reductase system of high activity is composed of soluble forms of cytochrome bj reductase and cytochrome bs... 

Methemoglobinemia as an adverse effect of prilocaine (8) has been reported more often than with any other local anesthetic. It is caused by a metabolite and is a particular problem in neonates, who have an immature methemoglobin reductase system and residual fetal hemoglobin, increasing the risk of sjmptomatic methemoglobinemia. 

Specific therapy for toxic methemoglobinemia involves the administration of methylene blue, which acts as an electron transfer agent in the NADPH-methemoglobin reductase reaction and thereby increases the activity of this system several fold (Figure 34-3). Methylene blue and sulfhemo-globin cause spectral interference in the measurement of methemoglobin with some co-oximeters but not with the Evelyn-Malloy method. ... 

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