Synergism of magnesium deficiency and nickel toxicity in growth and bone development

The authors examined effects of Mg level and of Ni in diets of growing rats. Male rats weighing 100 g were fed a diet adequate, low or high in Mg and adequate in other nutrients. After a week, LoMg and HiMg groups were sub-divided and fed 0 or 500 ppm Ni for the remaining 7 weeks. Animals fed LoMg+Ni gained less than half as much weight and ate about 75% as much ration as other groups. Food efficiency was reduced due to added Ni for LoMg. Many measurements related to growth showed this interaction of Mg and Ni, with low values in LoMg+Ni group, compared with all others. Spleen and thymus wt/g body wt increased in LoMg+Ni, while femurs and vertebrae were lightest, contained the least ash, and withstood the least force before breaking in a 3-point flexure test. However, because femurs of LoMg+Ni rats were small, the calculated breaking stress was greatest. Bones of LoMg rats supported a greater load than those of Ctl or HiMg, but breaking stress of femur was similar at all 3 levels of Mg when Ni was not fed. Overall, the LoMg diet produced little evidence of deficiency except when Ni was added; conversely,more » dietary Ni was much less toxic with HiMg than with LoMg.« less