Phospholipid synthesis in the human arterial intima.

The accumulation of lipids within the arterial intima represents an important feature in the development of the atherosclerotic lesion. Although much interest has been centered on the relationship between blood lipid levels and atherosclerosis, limited information is available in inan concerning the intimal metabolism of lipids and its possible role in lipid accumulation within the vessel wall. Previous studies indicate, however, that the human intima is in fact a dynamic tissue involved in a number of metabolic processes (2), and preliminary observations-suggest that the human intima can synthesize lipids, proteins, and lipoproteins (3, 4). Interest in the arterial metabolism of phospholipids is derived in part from the apparent biological role of phospholipids in the transport of lipids (5) and from the observations that the total phospholipid content of the arterial wall increases with the severity of atherosclerosis (6, 7). All phospholipid groups appear to share in this increase, although the major rise of phospholipid in the atherosclerotic lesion occurs in the sphingomyelin fraction (7, 8). Studies in rabbits by McCandless and Zilversmit have'demonstrated intimal phospholipid synthesis and have suggested that this local synthesis accounts for the major source of arterial phospholipid (9). Subsequent indirect studies in man have likewise suggested the presence of local intimal synthesis on the basis of higher phospholipid specific activities in the