Developmental changes of aldehyde oxidase in postnatal rat liver.

In this study, the developmental changes and variability of aldehyde oxidase in postnatal rat liver were examined. Postnatal day 1, 7 and 14 rats showed little or no liver aldehyde oxidase activity, as evaluated in terms of the activities for oxidation of benzaldehyde to benzoic acid, N-1-methylnicotinamide (NMN) to N-1-methyl-2-pyridone-5-carboxamide (2-PY) and N-1-methyl-4-pyridone-3-carboxamide (4-PY), and methotrexate (MTX) to 7-hydroxymethotrexate (7-OH-MTX). However, these oxidase activities were markedly increased in liver cytosol from the rats after postnatal day 14.

In vivo-in vitro relationship of methotrexate 7-hydroxylation by aldehyde oxidase in four different strain rats.

The in vivo metabolism of methotrexate (MTX) to 7-hydroxymethotrexate (7-OH-MTX) was studied using four strains of rats. When MTX was administered to these rats, 7-OH-MTX was detected as the major in vivo metabolite, mainly in bile and feces, and also slightly in the urine. There were marked strain differences in the amounts of 7-OH-MTX excreted in bile, feces and urine.