Effect of hypercholesterolemia on cholinephosphotransferase activity in rabbit and rat vessel walls

The activity of cholinephosphotransferase (EC 2.7.8.2, CPT) which catalyses de novo synthesis of phosphatidylcholine (PC) was studied in aortas of rabbits and rats, and in brain microvessels of rabbits with a cholesterol feeding-induced hypercholesterolemia. Cholesterol feeding produced a marked atheromatous change in rabbit aortas but not in rat aortas. The aortas of cholesterol-fed rabbits displayed a significantly higher CPT activity than the controls. On the other hand, the aortic CPT activity of cholesterol-fed rats was not different from that of control rats. The brain microvessels of cholesterol-fed rabbits having atheromatous aortic lesions did not show any lipid deposition, and CPT activity was similar to that of control rabbits. A tocopherol-deficient, high-cholesterol diet produced microscopical lipid deposits in rat aortas, and CPT activity of these aortas was significantly higher than that of aortas of rats on tocopherol-supplemented diets containing either a normal or high amount of cholesterol. The increase in CPT activity in atheromatous lesion might be closely related to lipid deposition in vessel walls and may be a cause of the increase in PC content in these lesions. Further studies are required to clarify the mechanism of activation of CPT activity in atheromatous conditions.