The influence of calcium and magnesium on manganese transport and utilization in Mice.

The influence of high but not extreme concentrations of Ca and Mg in water (25 µmol/mL) and of similar concentrations in food (25 µmol/g) on the absorption and retention of(54)Mn in mice was investigated. Addition of either Ca or Mg reduced the absorption of(54)Mn from water (administered by intragastric intubation) and from food (a portion made available for consumption during 1.5 h) by more than 50%. The retention of intraperitoneally injected(54)Mn was not influenced by addition of Ca or Mg (25 µmol/mL) to the drinking water. In mice fed a Ca-depleted diet during 2 wk prior to dosage, the absorption of(54)Mn from an intubated aqueous solution was increased by more than 100% compared to that in mice fed a Ca-adequate diet. In mice fed a Mg-depleted diet or a Ca- or Mg-replete diet for 2 wk, no changes in the absorption of(54)Mn were observed. In mice fed a Ca,Mg-depleted diet after(54)Mn administration, the turnover of absorbed(54)Mn was strongly increased, probably as a result of increased absorption of stable Mn from the diet. The results indicate that the uptake of Mn could be higher in soft water regions than in hard water regions.