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.