DOI: 10.5581/1516-8484.20120003 All pigments of hemoglobin (oxyhemoglobin, methemoglobin, sulphemoglobin and carboxyhemoglobin) are of clinical importance and each has a laboratorial characteristic in the absorption spectrum. Methemoglobin, in which the ferrous iron atom of the heme group has been oxidized to a ferric iron atom, is unable to carry molecular oxygen. Various red cell enzymes conv...

The volume changes for the binding of various ligands to metmyoglobin and methemoglobin have been determined from the effect of pressure on the binding constants (for metmyoglobin) and by direct dilatometry (for methemoglobin). The volume changes associated with the binding of cyanide and azide ions to methemoglobin are pH-dependent. The volume change for the binding reaction is evidently affec...

We have measured the optical absorption and scattering coefficient spectra of a multiple-scattering medium (i.e., a biological tissue-simulating phantom comprising a lipid colloid) containing methemoglobin by using frequency-domain techniques. The methemoglobin absorption spectrum determined in the multiple-scattering medium is in excellent agreement with a corrected methemoglobin absorption sp...

An assay for determining the rate of methemoglobin reduction in hemolysates of human erythrocytes has been developed. The rates obtained by this assay, when corrected for dilution, are comparable to those obtained with intact cells. Increased ionic strength inhibits the reaction, whereas EDTA increases the rate of reduction. The rate with NADPH as electron donor is 65-70% of the rate with NADH....

Although the efficacy of induced methemoglobinemia in cyanide poisoning has been demonstrated both therapeutically and prophylactically (l),l the tissue reactions involved in the protection of animals from the lethal effects of the cyanide ion by methemoglobin are only imperfectly understood. Presumably, cyanide interferes with cellular respiration by forming a slightly dissociable complex with...

INTRODUCTION Hemolytic anemia, the early removal of erythrocytes from the circulation, has been recognized as a side effect of drugs and other environmental chemicals. Formation of methemoglobin (MetHb) following chemical exposure is the first hemotoxic response in the induction of hemolytic anemia. The purpose of this study was to compare the species differences in the chemical induction of Me...

On the basis of nuclear magnetic resonance spectra, Davis, Charachc, and Ho (1) have recently suggested that the heme groups of the a! and /3 methemoglobin chains are not equivalent. Gibson, Parkhurst, and Geraci (2) have reported biphasic kinetics for the reaction of methemoglobin with a variety of iron-coordinating ligands. These results were also explained assuming nonequivalent heme groups....

We have stated in a preliminary report that the cyanosis observed in individuals treated with sulfanilamide is due to methemoglobin, and rarely, to sulfhemoglobin (1). We recognized at the time that attempts had been made to explain the presence of cyanosis on a different basis.. Marshall and Walzl (2) maintained that a black pigment derived from sulfanilamide, and present in the blood, was the...