Harrison J D, Haines J W, Popplewell D S
National Radiological Protection Board, Chilton, Didcot, Oxon, UK.
Int J Radiat Biol. 1990 Jul;58(1):177-86. doi: 10.1080/09553009014551531.
The gastrointestinal absorption of 95Nb ingested in milk by adult guinea pigs on a milk-supplemented diet was estimated as 0.8 +/- 0.2% (SEM; n = 4) and a value of 1.4 +/- 0.2% was obtained for guinea pigs fasted for 24 h before and 2 h after the oral administration of 95Nb in a citrate solution. The absorption in 2-day-old animals given the 95Nb-citrate solution was estimated as 1.5 +/- 0.2% (SEM; n = 3). These results support the values currently used for radiological protection purposes to calculate doses from the ingestion of niobium isotopes; these are 1% for adults and 2% for infants in the first year of life. Intestinal retention of niobium in newborn guinea pigs was low, unlike retention in other species, but consistent with observations of the retention of other elements in guinea pigs. It is considered that retention in human neonates is likely to be most similar to that in guinea pigs. Whole-body retention of 95Nb after systemic administration in citrate solution was slightly lower in 2-day-old guinea pigs than in adults, with rapid excretion of about 50% over the first day compared with 40% in adults. Subsequent clearance was similar in the two age groups with a retention half-time of about 30 days.
对食用补充牛奶饮食的成年豚鼠经胃肠道对牛奶中摄入的95Nb的吸收进行了估算，结果为0.8±0.2%（标准误；n = 4）；对于在口服95Nb柠檬酸盐溶液前禁食24小时且给药后禁食2小时的豚鼠，吸收值为1.4±0.2%。给2日龄动物口服95Nb柠檬酸盐溶液后的吸收估算值为1.5±0.2%（标准误；n = 3）。这些结果支持目前用于放射防护目的、从铌同位素摄入计算剂量时所采用的值；即成年人为1%，1岁以内婴儿为2%。新生豚鼠体内铌的肠道潴留量较低，这与其他物种不同，但与豚鼠体内其他元素潴留情况的观察结果一致。据认为，人类新生儿的潴留情况可能与豚鼠最为相似。2日龄豚鼠经柠檬酸盐溶液全身给药后95Nb的全身潴留量略低于成年豚鼠，第一天约有50%快速排出，而成年豚鼠为40%。随后两个年龄组的清除情况相似，潴留半衰期约为30天。
