Effect of Magnesium Deficiency on Blood Pressure in Normal Rats Fed Cadmium

Abstract

We attempted to further define the effects of an Mg-deficient diet on blood pressure in rats fed Cd for long periods. Twenty male Wistar rats were grouped according to four different diets: normal diet (N rats); normal diet supplemented with Cd at a dose of 50 µg/g of diet (N rats fed Cd); Mg-deficient diet (D rats); and Mg-deficient diet supplemented with Cd at a dose of 50 µg/g of diet (D rats fed Cd). Each diet was given for 60 days. N rats fed Cd developed a duration-limited increase in blood pressure: by day 60, increased blood pressure returned to the level seen in N rats. Mg deficiency lowered the Cd-induced increase in blood pressure and this response was more pronounced on day 60. A variety of independent blood pressure regulatory mechanisms was investigated. Although Mg deficiency tended to occur at lower concentrations of Cd and metallothionein in the heart of N rats fed Cd and the Cd concentration was less than 5 µg/g of tissue, Mg deficiency increased the Ca concentration in the hearts of N rats fed Cd while a decrease in urinary Na excretion and an increase in water retention were not observed. Diet-related toxic clinical signs in D rats fed Cd induced marked blush on the ears and fingers, indicating vasodilatation had occurred. These findings may have been a factor in the pronounced reduction in blood pressure seen.

Long-Period-Effect of Moderate Mg Deficiency on Circulation Parameters in Rats Treated with Cadmium

“…9) We have also reported that the route of administration and body burden of Cd used in present study produced increase in blood pressure and plasma aldosterone level. 11,14) Present study by using the moderately Mg-deficient diet demonstrated significant interaction between Mg deficiency and Cd treatment on Cd concentrations in the heart and aorta (Fig.…”

“…8) We have recently reported that decreased blood pressure was observed in severe Mg-deficient rats fed Cd. 9) In light of these reports, we speculated that the effects of moderate Mg-deficiency and Cd treatment might interact to affect circulation parameters in rats, which results in increased blood pressure.…”