Effects of magnesium deficiency on purine-base metabolism in rats

Abstract

Molybdenum (Mo) is a constituent of Mo cofactor (MoCo) that is indispensable for the activity of molybdoenzyme such as xanthine oxidase (XO). This molybdoenzyme plays an important role on purine-base metabolism in the liver where Mo mainly exists as MoCo. Our previous experiment indicated that magnesium (Mg) deficiency increased Mo concentration in rat liver. We hypothesized that the increase in Mo reflects up-regulating expression of molybdoenzyme such as XO in the liver of Mg-deficient rats. We investigated the effect of Mg deficiency on the metabolism of purinebase in rats. Twelve growing male rats were given a control diet or an Mg-deficient diet for 4 weeks. Urine was collected every day during the last 5 days in the feeding trial. At the end of feeding trial, liver was collected, and the hepatic XO activity and the concentration of purine-base metabolites such as hypoxanthine, xanthine, uric acid, and allantoin were determined. Additionally, urinary excretion of purine-base metabolites was determined. Mg deficiency did not affect the XO activity and the concentration of purine-base metabolites in the liver. One the other hand, urinary excretion of uric acid and allantoin was significantly decreased by Mg deficiency. These results suggested that the increase in hepatic Mo concentration does not affect purine-base metabolism in the liver of Mg-deficient rat, but that Mg deficiency decreases urinary excretion of purine-base metabolites.