Effect of 3-Amino-1,2,4-triazole on Catalase and Formation of Methemoglobin from Oxyhemoglobin in Erythrocyte by Superoxide Radicals

概要

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The formation of methemoglobin (metHb) from oxyhemoglobin (oxyHb) in the erythrocyte by O_2-was studied under the O_2--generating system of photoactivated riboflavin with oxygen by using a catalase inhibitor, 3-amino-1,2,4-triazole (AT). In the AT-treated erythrocytes in vitro which have little catalase activity, the rate of metHb formation was increased remarkably compared with that of untreated normal erythrocyte. Furthermore, catalase added to 60 unit/ml to the suspending medium contained AT-treated erythrocytes caused a strong inhibition of formation of metHb, suggesting that H_2O_2 is generating in the external medium of erythrocytes by the reaction of photoactivated riboflavin or spontaneous dismutation of O_2-. Addition of superoxide dismutase (5μg/ml) caused an acceleration but not inhibition of the metHb formation. Hemolysis was scarcely observed in the time course of this experiment. These results may be interpreted that H_2O_2 generated in the outside of cells moves across the membrane and results in oxidative attack to oxyHb in the erythrocyte without the hemolytic effect. Another possible participation of O_2- may be suggested to exert its enhanced oxidation of oxyHb, namely that O_2- generated in the outside of cells may pass through the membrane directly.
公益社団法人日本薬学会の論文
1978-11-25