Lipid Distribution and Metabolism in Two Areas of Aorta of Normal and Cholesterol-fed Rabbits

Abstract

Lipid distribution and phospholipid metabolism of the aortic arch and descending limb of aorta, plasma and liver were determined in groups of rabbits fed a normal diet and high-cholesterol diet for 40 and 70 days duration. In all groups, the descending limb of aorta had significantly less total lipid concentrations due primarily to decreased neutral fat content compared with the lipid constitution of the aortic arch of the same type of animal. Also, in normal rabbits the specific activity of phospholipid in the descending aorta was significantly greater than that of the aortic arch. However, this distinction in phospholipid synthesis between the 2 regions of aorta was not found in rabbits fed the cholesterol-supplemented diet. The radioactivity data indicated that this was due to an increased rate of for -mation of phospholipid in the aortic arch of cholesterol-fed rabbits, particularly those fed for 70 days; and the altered rate of metabolism of phospholipids probably was related to the development of atheromatous lesions in the aortic arch of these animals. It was noted that plasma lipids distribution, hypercholesterolemia, plasma phospholipids synthesis, and lipids interrelationships of the cholesterol-fed rabbits were not different although the dietary rigime of one group was almost twice that of the other in its duration. Yet visible atheromatosis in the aortic arch was severe in the 70-day group, and aortic cholesterol content and phospholipid metabolism was different from those of lesser time on the cholesterol diet as well as the normal diet. Results were discussed in relation to general problem of local factors in arterial wall influencing localization and development of atherosclerosis.