INVITRO METABOLISM OF PERMETHRIN ISOMERS BY CARP AND RAINBOW-TROUT LIVER-MICROSOMES

Carp liver microsomal esterases hydrolyze trans-permethrin [an insecticide] much more extensively than cis-permethrin, and the same relationship holds for rainbow trout liver microsomes, although they appear to be less active. There is a strong preference with both isomers and microsomal mixed-function oxidases of both species for hydroxylation at the 4'' position of the alcohol moiety to other sites. The methyl group trans to the carboxy is usually hydroxylated more extensively than the cis-methyl group, the greatest specificity being with carp microsomes acting on cis-permethrin. The bile of rainbow trout exposed in vivo to 14C-alcohol-labeled trans-permethrin contains little or no permethrin, but instead mainly consists of conjugates cleaved by .beta.-glucuronidase but not by aryl sulfatase.