Daily Rhythm in Hepatic and Renal Aldehyde Oxidase and Xanthine Oxidase in Male and Female Uromastyx microlepis

The activities of aldehyde oxidase and xanthine oxidase were determined in partially purified preparations from livers and kidneys of male and female Dhubb, Uromastyx microlepis, four times daily at equal intervals. The maximum activity of male and female hepatic aldehyde oxidase appeared at 2100 h, whereas the minimum activity was observed at 0300 h, using phthalazine and 3-methylisoquinoline as substrates. The differences between maximum and minimum activity were statistically significant (P < 0.05). No fluctuation was observed in male renal aldehyde oxidase activity with phthalazine, whereas female enzyme showed significant daily variations (P < 0.0005). Using 3-methyliosoquinoline as a substrate, both male and female renal aldehyde oxidase showed drop in activity at 1500 h, and the differences between minimum and maximum were significant (P < 0.0005). Circadian variations in male and female renal xanthine oxidase activities were observed using xanthine as a substrate. The main peak appeared at 0300 h and minimum activity from 1500 to 2100 h, and the difference between rhythmic extremes was statistically significant (P < 0.03).