Magnesium Deficiency in the Guinea Pig. Mineral Composition of Tissues and Distribution of Acid-Soluble Phosphorus

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Abstract
Osseous and soft tissues from magnesium-deficient and control guinea pigs fed two levels of phosphorus, 0.4 and 1.7%, were analyzed for ash, calcium, phosphorus and magnesium. The distribution of the acid-soluble phosphorus in kidney, heart and muscle was also investigated. The concentrations of ash, calcium and phosphorus in kidney, muscle and heart were greatly increased, whereas that of magnesium was slightly decreased by the deficiency. A dietary magnesium level of 0.06% maintained near normal tissue composition with the low-phosphorus diet, whereas even 0.34% of magnesium did not maintain normal tissue composition in animals fed the high-phosphorus diet. It may be concluded that a higher magnesium level is required to maintain tissue composition than to support maximal growth and that the requirement for maintenance of normal tissue composition varies with the tissue. Magnesium deficiency caused no major change in the ash, calcium or phosphorus content of bones and teeth, but caused a marked lowering of magnesium. The increase in total acid-soluble phosphorus of soft tissues from magnesium-deficient animals was accounted for almost entirely as inorganic phosphorus. The excess inorganic phosphorus and calcium were in approximately the proportions found in tricalcium phosphate.