methemoglobin

(redirected from ferrihemoglobin)
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methemoglobin

 [met-he´mo-glo″bin]
a hematogenous pigment formed from hemoglobin by oxidation of the iron atom from the ferrous to the ferric state. A small amount is found in the blood normally, but injury or toxic agents convert a larger proportion of hemoglobin into methemoglobin, which does not function as an oxygen carrier.

met·he·mo·glo·bin (metHb),

(met-hē'mō-glō'bin),
A transformation product of oxyhemoglobin resulting from the oxidation of the normal Fe2+ to Fe3+, a process that converts heme to hematin; because methemoglobin contains water in firm union with ferric iron, it is chemically different from oxyhemoglobin; found in sanguineous effusions and in the circulating blood after poisoning with acetanilid or potassium chlorate, among other substances.
Synonym(s): ferrihemoglobin

methemoglobin

/met·he·mo·glo·bin/ (met-he´mo-glo″bin) a hematogenous pigment formed from hemoglobin by oxidation of the iron atom from the ferrous to the ferric state. A small amount is found in the blood normally, but injury or toxic agents convert a larger proportion of hemoglobin into methemoglobin, which does not function as an oxygen carrier.

methemoglobin

(mĕt-hē′mə-glō′bĭn)
n.
A brownish-red form of hemoglobin that occurs when hemoglobin is oxidized either during decomposition of the blood or by the action of various oxidizing drugs or toxic agents. It contains iron in the ferric state and cannot function as an oxygen carrier.

methemoglobin

[met′hēməglō′bin, met·he′məglō′bin]
a form of hemoglobin in which the iron component has been oxidized from the ferrous to the ferric state. Methemoglobin cannot carry oxygen. It is a product of various oxidative reactions that constitute normal metabolic activity and is normally present in only trace amounts (about 1%) in the blood, but may increase in chronic inflammation. Maintenance of levels occurs by an active enzymatic reducing capability, the nicotinamide-adenine dinucleotide-methemoglobin reductase system present in normal red blood cells. Also spelled methaemoglobin. See also hemoglobin.

met·he·mo·glo·bin

(metHb) (met-hē'mŏglō'bin)
A transformation product of oxyhemoglobin because of the oxidation of the normal Fe2+ to Fe3+, thus converting ferroprotoporphyrin to ferriprotoporphyrin; useless for respiration; found in bloody effusions and in the circulating blood after poisoning with acetanilid, potassium chlorate, and other substances.
Synonym(s): hemiglobin, methaemoglobin.

Methemoglobin

A compound formed from hemoglobin by oxidation.
Mentioned in: Nephrotoxic Injury

methemoglobin

a compound formed from hemoglobin by oxidation of the iron atom from the ferrous to the ferric state. A small amount of methemoglobin is normally present in the blood, but injury or toxic agents convert a larger proportion of hemoglobin into methemoglobin, which does not function as an oxygen carrier. See also hemoglobin.

methemoglobin reductase pathway
an intraerythrocyte enzyme system that maintains hemoglobin in a reduced state. A deficiency of the enzyme, resulting in the formation of methemoglobinemia with insufficient oxygenation of the blood, occurs in the dog.