Cholesterol-fed Dogs Research Articles

Canine atherogenesis following I 131 administration and cholesterol feeding.

Atherogenesis in I131-treated cholesterol-fed dogs was evaluated utilizing tissue lipid and polysaccharide, serum lipid and lipoprotein analyses. Coronary artery lesions antedated aortic lesions and both were characterized first by ground substance change without lipid accumulation. Lipids other than cholesterol then appeared, associated with varying degrees of cellular proliferation, subintimal hemorrhage and involvement of vasa vasorum and media. Marked cholesterol but not phospholipid accumulation characterized late lesions. Metachromasia was noteworthy only in fibrotic lesions. Aortic tissue hexose and hexosamine values usually were normal. Liver analyses revealed increased glycogen, especially in animals with marked reduction in high density serum lipoproteins. These animals also had highest concentrations of serum cholesterol, lipid P and lower density lipoproteins, and the most severe atheromata. Serum C/P ratios increased with increasing cholesterol levels. At serum cholesterol levels above 1000 mg %, the increments in C/P ratios were relatively smaller. Hypercholesterolemia in excess of 450 mg % for 1 year appears requisite to atherogenesis in the I131-treated cholesterol-fed dog, while comparable hypercholesterolemia in I131-treated dogs not fed cholesterol does not lead to atheroma formation.

Dietary cholesterol and adrenal regulation of plasma lipids.

Adrenalectomized dogs maintained on desoxycorticosterone acetate manifest a progressive depletion of plasma phospholipid and cholesterol. Within a 4-week period a mean decrease of 60% is observed. The daily addition of cholesterol to the Purina chow diet prevented the hypolipemic response and resulted in significant elevation in the concentration of plasma cholesterol. The feeding of an identical amount of cholesterol to dogs with intact adrenals was not associated with any alteration in plasma lipid levels. The feeding of identical amounts of highly saturated fats or soya lecithin to adrenalectomized dogs resulted in the characteristic decline of plasma phospholipid and cholesterol. A significant contribution of the adrenal gland to the regulation of plasma lipid metabolism in normal and cholesterol-fed dogs is indicated.