ANALYSIS OF HEMOGLOBIN DERIVATIVES BY CAPILLARY ISOELECTRIC-FOCUSING AND ITS APPLICATION IN THE ANTIDOTAL RESEARCH OF CYANIDE POISONING

Cyanide toxicity can be reduced by the use of methemoglobin (MetHb) fo rmers, and antidotal dosage is based on the extent of MetHb formation. Hemoglobin and ferrihemoglobin (MetHb, hemimethemoglobins) alpha(2+)b eta(3+) and (alpha(2+)beta(3+), tetracyanmethemoglobin, and dicyanmeth emoglobin) concentrations in human, pig, and mouse blood were determin ed after separation by isoelectric focusing with an octyl-bonded capil lary. The predominant species formed in blood when MetHb formers, such as potassium ferricyanide, hydroxylamine, sodium nitrite, and 4-dimet hylaminophenol (DMAP), added at molar ratios ranging from 1:10 to 1:1 to hemoglobin, are the valency hybrid intermediates alpha(3+)beta(2+) and alpha(2+)beta(3+). In the detoxification of cyanide with methemogl obin, an intermediate dicyanhemimethemoglobin was demonstrated to be t he predominant species in the formation of tetracyanmethemoglobin. Com plex mixtures of hemoglobin derivatives were observed with DMAP at 1:1 or greater molar ratio to hemoglobin. Comparison of the MetHb values obtained with a hemoxometer indicated that the valency hybrids were me asured as MetHb and the values of oxidized hemoglobin were overestimat ed. In cyanide poisoning, incorrect dosages of MetHb formers could be calculated, and misinterpretation of MetHb data would result from meth ods that fail to discriminate among the various species of MetHb. (C) 1996 Academic Press, Inc.