Abstract
The influence of change in the lighting schedule on the circadian variation of uric acid metabolism was observed in the rat.
Under regular light-dark alternation, the level of serum uric acid and allantion was highest at 2pm and lowest at 2am. The circadian rhythm was also observed in enzyme activity of the liver. That is, the activity of xanthine oxidase showed a circadian variation with the same pattern as that of uric acid and allantoin. Uricase activity exhibited a circadian fluctuation, with the highest activity at 10am and the lowest at 6pm. However, rats exposed to constant light or dark manifested an abolition of the circadian rhythm of uric acid metabolism.
