维生素B_(12)与叶酸对辐射损伤的效应研究——一、尿中亚胺甲基谷氨酸排出量

选取刚断奶的雄性大鼠,饲以含有1％琥珀酰磺胺噻唑的、无维生素B_(12)和叶酸的饲料,并经口每日每鼠补给不同量维生素B_(12)和叶酸,以组氨酸负荷尿中亚胺甲基谷氨酸的排出量为主要指标,观察急性辐射损伤时维生素B_(12)与叶酸的营养效应。其主要结果如下: 1.当大鼠仅摄食实验饲料,3—5周内就出现了明显的缺乏维生素B_(12)与叶酸的症状,如食欲锐减,体重增长率减慢继而下降,尾血白细胞总数下降,24小时尿中亚胺甲基谷氨酸排出量明显高于正常(由正常的0.55mg增至14～17mg)等。摄食维生素B_(12)0.02μg与叶酸0.5μg组的上述症状较未补充者轻。摄食维生素B_(12)0.1μg与叶酸2.5μg组的食欲、体重增长率等已较正常,但组氨酸负荷尿中亚胺甲基谷氨酸排出量仍高于正常(由正常0.55mg增至3.41mg)。摄食维生素B_(12)0.3μg与叶酸7.5μg组在上述各项指标上均显示与正常无差别。) 2.上述经口补充不同量维生素B_(12)与叶酸的各组动物,经700rad照射(实验饲养36天时后,除摄食维生素B_(112)0.3μg与叶酸7.5μg组外,其余两组的组氨酸负荷尿中亚胺甲其谷氨酸排出量均比照射前更为增加,(分别由12.36增至23～28mg、3.41增至6～9mg/24h),显示照后此两种维生素的缺乏或不足程度加重。 3.摄食维生素B_(12)0.02μg与叶酸0.5μg的大鼠?

STUDIES ON THE EFFECT OF VITAMIN B12 AND FOLIC ACID ON RADIATION DAMAGE 1. URINARY EXCRETION OF FORMIMINOGLUTAMIC ACID

Weanlimg male rats fed on synthetic diet containing 1% succinylsulfa-thiazole and devoid of vitamin B12 and folic acid for 3-5 weeks, developed syndromes of the vitamins deficiency, i.e. poor food consumption, low growth rate, decrease in white cell count and marked increase in formimi-noglutamic acid excretion.Nevertheless, the others had an intake of vitamin B12 (0.02 μg/day/-rat) and folic acid (0.5μg/day/rat) for a 36-day period, also showed signs of vitamins deficiency. But when given a daily dose of 0.1 μg of vitamin B12 and 2.5 ug of folic acid, the rats had a good appetite and grew well, and excreted more formiminoglutamic acid than normal rats, when they were given a loading dose (0.05 g/rat) of histidine. Under the similar feed- ing condition, rat ingesting a daily dose of 0.3 ug of vitamin B12 and 7.5ug of folic acid, showed no obvious syndomes of the vitamins deficiency.After the rats were fed on the same diet and given with vitamin B12 (0.02 ug/day/rat) and folic acid (0.5ug/day/rat) for a 36-day period, the animals developed increased radiosensitivity. After total-body irradiation (700 rad), the food consumption, growth rate and survival rate in this group were lower than those in other groups ingesting individually 0.1 ug of vitamin B12 and 2.5 ug of folic acid or 0.3ug of vitamin B12 and 7.5 ug of folic acid daily.After irradiation, in the group of 0.02 ug of vitamin B12 and 0.5 ug of folic acid or 0.1 ug of vitamin B12 and 2.5 ug of folic acid in daily in-gestion there was a considerable increase in formiminoglutamic acid with a loading test of histidine(0.05 g/rat) than before. The results showed that the radiation intensified vitamins deficiency in rats.