Studies on toxicities of biphenyl ether herbicides and their analogues to fish. I. The methemoglobin-formation by the nitroso-derivatives in white-spotted char, Salvelinus leucomaenis, erythrocytes.

Abstract

The methemoglobin formation by the nitroso-derivatives of biphenyl ether herbicides (2, 4-dichloro p-nitrobiphenyl ether and 2, 4, 6-trichloro p-nitrobiphenyl ether) and their analogues was investigated in suspensions of white-spotted char erythrocytes. All of the nitroso-derivatives used, induced the methemoglobin formation in white-spotted char erythrocytes as well as human erythrocytes and the activity of methemoglobin formation among the nitroso-derivatives was the most potent in nitrosobenzene followed by p-nitrosobiphenyl ether, 4-chloro p-nitrosobiphenyl ether, 2, 4-dichloro p-nitrosobiphenyl ether and then 2, 4, 6-trichloro p-nitrosobiphenyl ether in erythrocytes of both species. This order among the nitroso-derivatives was dependent on the number of chlorine rather than on its position of substitution in the phenoxy group. The mechanism of methemoglobin formation by the nitroso-derivatives was similar in erythrocytes of both species and on the requirement of NADPH-dependent enzyme systems, and that of methemoglobin reduction was similar, too, on reception of NADH-dependent enzymatic process.