動脈平滑筋細胞の膜リン脂質に関する研究

Abstract

We already reported the effects of hyperlipidemic rabbit serum on cultured smooth muscle cells and various organelle membrane phospholipids. This findings suggest the possibility that cell proliferation by attack of hyperlipidemic serum might be resistance to develop atherosclerosis. In the present study, we have observed the changes of membrane phospholipids on experimental hypercholesteremic rabbits.Fifteen male New Zealand white rabbits were fed with diet containing 1.5% cholesterol and were divided into three groups by cholesterol feeding period. And, control group (five male New Zealand white rabbits) was fed with standard rabbit's diet.Cells of intima-media were obtained from the thoracic aorta according to method described by Chamley et al. Lipids were extracted by Folch's method. Technique of thin layer chromatography was applied to determine the composition of various phospholipids of the membranes.The results are as follows.1) Hyperlipidemia was increased according to the period of cholesterol feeding.2) In distribution of various serum phospholipids, Sphingomyelin (SPH) was most increased and Lysophosphatidyl choline (LPC) was increased, but Phosphatidyl choline (PC) and Phosphatidyl ethanolamine (PE) were decreased. This tendency significantly increased according to the period of cholesterol feeding.3) In the cells of intima-media obtained from the thoracic aorta, CE and TG increased and FC, PL and FA decreased in the cholesterol feeding groups as compaired with those in the controls. This tendency significantly increased according to the period of cholesterol feeding.4) In the composition of phospholipids in cells of aortic intima-media, SPH increased, LPC and PC also increased, but PE, Phosphatidyl inositol (PI) decreased in the control group.5) Contrary, in atherosclerotic rabbits which were fed with diet containing 1.5% cholesterol for one month, SPH decreased and Phosphatidic acids (PA), PE increased.6) From above mentioned results, it is concluded that in early period of atherosclerosis, cells of aortic intima-media might play protective reaction against to the development of atherosclerosis, since cell membrane seems to increase biological activities from the aspect of change in the phospholipid composition caused by the cholesterol feeding.