Catalytic activity and immunohistochemical localization of flavin-containing monooxygenase in rat kidney.

The presence of flavin-containing monooxygenase activity was examined in rat kidney microsomes using N,N-dimethylaniline and methimazole as substrates. Western immunoblot analysis using antisera to porcine liver and rabbit lung flavin-containing monooxygenase indicated immunological cross-reactivity between rat kidney, porcine liver and rabbit lung flavin-containing monooxygenase. Immunohistochemical studies using antisera to rabbit lung flavin-containing monooxygenase demonstrated localization of this enzyme in the proximal and distal convoluted tubules of the renal cortex, the collecting ducts in the renal medulla, but not the glomeruli. This observation indicates the colocalization of flavin-containing monooxygenase and cytochrome P-450 in the metabolically active and absorptive compartment of the renal parenchyma.