HIGH DIETARY ALUMINUM AFFECTS THE RESPONSE OF RATS TO SILICON DEPRIVATION

Antagonistic interactions between silicon and aluminum occur in living organisms. Thus, an experiment was performed to ascertain whether hig h dietary aluminum would accentuate the signs of silicon deprivation i n rats and conversely whether silicon deprivation would accentuate the response to high dietary aluminum. The experiment was factorially arr anged with two variables: silicon as sodium metasilicate, 0 or 40 mu g /g diet, and aluminum as aluminum citrate, 0 or 500 mu g/g diet. After 9 wk, body weights and plasma urea nitrogen were higher and plasma co ncentrations of threonine, serine, glycine, cystine, and methionine we re lower in silicon-adequate than silicon-deprived rats. High dietary aluminum significantly decreased plasma phenylalanine. An interaction between aluminum and silicon affected plasma triglyceride, cholesterol , and phosphorus concentrations. High dietary aluminum decreased these variables when silicon was absent from the diet, but increased them w hen silicon was present. Skull iron and silicon concentrations were de creased and iron and zinc concentrations in the femur were increased b y the addition of 500 mu g Al/g diet. High dietary aluminum decreased tibia density in silicon-adequate rats, but increased tibial density i n silicon-deprived rats. The findings indicate that in rats, high diet ary aluminum can affect the response to silicon deprivation and dietar y silicon can affect the response to high dietary aluminum.