The Circadian Variation of the Activity of Hepatic Molybdenum Hydroxylases in the Female Syrian Hamster PDF

Keywords

Hamsters, Syria, liver

Abstract

The activities of molybdenum hydroxylases, aldehyde oxidase and xanthine oxidase, were determined eight times daily (at equal intervals) in partially purified preparations of liver of adult female hamsters. A marked diurnal variation of aldehyde oxidase activity was observed with the substrates used (phthalazine, 3- methylisoquinoline, phenanthridine). The maximum enzyme activity occurred at 0600 hr, whereas the minimum activity occurred at 0300, 0900 and 1800 hr. The differences between the maximum and minimum enzyme activities were highly significant (P< 0.005). Xanthine oxidase also showed circadian variation when xanthine was used as substrate. The maximum activity of xanthine oxidase occurred at 1500 hr whereas the minimum occurred at 0900 hr. The difference between the two extremes was statistically significant (P<0.01). These Results indicate that hamster liver aldehyde oxidase and xanthine oxidase exhibit circadian variation in activity.