Summary
Rats were pair fed a magnesium deficient or control diet. Plasma parathyroid hormone
(PTH) was estimated by radioimmunoassay using synthetic 1-34 PTH and intestinal calcium-binding
protein (CaBP) was quantified directly by RIA in proximal duodenum, distal ileum and
medium jejunum. In magnesium depleted rats, plasma magnesium levels were significantly
decreased, a fall in plasma phosphate paralleled the decrease in plasma magnesium
and plasma calcium levels were significantly increased after 14 days of magnesium
deficiency. A significant rise in plasma PTH was observed on day 7 and 14 after magnesium
deficiency. This increase disappeared on day 20. During the whole experimental period,
no significant differences in CaBP levels were observed between the two groups of
rats. Thus it is difficult to postulate an increase in vitamin D-dependent calcium
absorption to explain the hypercalcemia found in magnesium deficient rats. Neither
can the hypercalcemia be readily explained by an increased bone calcium mobilisation
due to transient PTH increase since previous results have reported decreased bone
resorption in magnesium deficient rats under similar experimental conditions.
Key-Words:
Magnesium Deficiency
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Parathyroid Hormone
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Calcium-Binding Protein
