The addition of cholesterol and cholic acid to a diet containing 24 mg. percent of magnesium, an amount normally required for young rats, resulted in magnesium deficiency in rats. This was characterized by hyperexcitability, hyperemia of the ears, calcium deposition in the kidney tubules, low serum magnesium levels, and decreased oxidative phosphorylation of heart mitochondria. All these lesions were prevented by raising the dietary magnesium level four to eight times.
Feeding the atherogenic diet produced the deposition of lipide in the aorta and in the heart valves. The extent of this intimal sudanophilia was reduced by large amounts of dietary magnesium although serum cholesterol values did not fall and usually rose. This represents perhaps the first clear cut disassociation between serum cholesterol values and the extent of intimal sudanophilia.
Raising the level of dietary protein from 10 to 20 per cent decreased the serum cholesterol levels and the extent of the kidney lesions. Thyroxine administration lowered the serum cholesterol values, abolished the kidney lesions and reduced the intimal sudanophilia. These effects occurred even though the serum magnesium levels remained low.