Further studies on experimental atherosclerosis and dietary pyrimidines: orotic acid, thiouracil, and uracil in male and female rats.

The coinparntivc potencies of uracil mid thiouracil in terms of thyroidal changes, hypercholcstcrcinin, azoteniia, and incipient atherosclerosis were determined in rats fed cholesterol and cholic acid. Higher dietary levels of uracil were required to produce changes similar to those seen with thiouracil. Certain dietary components related to uracil were also studied. Orotic acid was found to have a dramatic effect on female rats: it favored a markedly lower serum cholesterol level and less cardiovascular sudanophilia. AVhen orotic acid was combined with uracil, the uraeil-induced hypereholesteremia and atherogenesis were significantly inhibited, particularly in the females. Orotic acid also protected against the uraeil-induced thyroid hyperplasia in these females.