THE EFFECT OF VITAMIN B_(12) AND FOLIC ACID ON RADIATION DAMAGE 3. NITROGEN METABOLISM / 营养学报

ABSTRACT

Sixty male rats divided equally into three groups were fed with synthetic diet. In every group each rat was subcutaneously given with vitamin B12 and folic acid, but the administration dose for different group was different so that the first group showed nutritional insufficiency, the second almost normal and the third good nutritional condition.Having fed to four weeks, the nitrogen intake for the first group (0.36 ?0.01 g/day) was significantly lower than that for the second (0.45?0.02 g/day) or for the third (0.44 ?0.012 g/day). The same were true for urinary nitrogen and total nitrogen.Under histidine load of 50 mg per rat, the urinary nitrogen excretion in every group was increased, but the increased quantity was much more than the nitrogen content in histidine used for loading test. At the same while the urinary amino nitrogen and ammonia nitrogen for the first group were increased, but not for the second or for the third before and after the loading test.Twelve rats selected from every group were equally distributed into two subgroups, one being irradiated with 60Co ray 700 rad and other not irradiated taking as control. The loading tests of histidine were undertaken at 1st, 7th, 14th, 21th and 28th day. The results showed that the radiation damage, the decrease of food intake and histidine loading test might exaggerate the disturbance of nitrogen metabolism in rats suffered from nutritional insufficiency of vitamin B12 and folic acid, as shown in urinary amino nitrogen and ammonia nitrogen excretion, but higher administration of vitamin B12 and folic acid could eliminate the exaggeration and improve the disturbance of nitrogen metabolism as well.