The effect of magnesium deficiency on serum aldosterone in rats fed two levels of sodium.

Rats were fed 47 (deficient) and 606 ppm (adequate) magnesium with either 2,100 or 14,000 ppm sodium. Serum corticosterone and aldosterone levels were determined by randoimmunoassay in six rats from each treatment group killed on days 7, 14, and 28 of consumption of the experimental diets. Serum corticosterone levels were moderately, but not significantly, decreased in magnesium deficient animals. Serum aldosterone levels increased over time in the rats fed the lower sodium diet with adequate magnesium and were further elevated in magnesium deficient animals. In sodium loaded rats the increase in aldosterone levels in magnesium deficiency was less and occurred later. Retention and urinary excretion of sodium and potassium did not appear to be affected by magnesium status or the serum concentration of aldosterone. Possible mechanisms underlying the changes in aldosterone levels of magnesium depleted animals are discussed with reference to the known effects of magnesium deficiency on physiological functions.