Metabolism of atherogenic lipoproteins by smooth muscle cells of different phenotype in culture.

Abstract

Smooth muscle cells of the rabbit aorta, when grown in vitro, express 3 distinguishable forms of phenotype (contractile, reversible synthetic and irreversible synthetic). The interactions of these 3 smooth muscle phenotypes were compared with rabbit very low density lipoprotein (VLDL), low density lipoprotein (LDL) and very low density lipoprotein from cholesterol-fed rabbits (.beta.-VLDL). .beta.-VLDL showed saturable, high-affinity binding characteristics with each phenotype predominantly through the B/E receptor. The irreversible synthetic cells displayed the greatest binding capacity, and the contractile cells, the least. Binding and degradation of normal VLDL was less than that of .beta.-VLDL and higher than that of LDL. The irreversible synthetic cells showed substantial (.apprx. 3-fold) cholesteryl ester formation and cholesterol accumulation, and then only when incubated with .beta.-VLDL. Substantial stainable lipid, shown chemically to include triglyceride, cholesterol and cholesteryl ester, was observed only when irreversible synthetic cells were expased to .beta.-VLDL. The high capacity of irreversible synthetic-state, smooth muscle cells to bind and accumulate .beta.-VLDL in contrast to the relative immunity of contractile cells may be relevant to the genesis of atherosclerosis in the rabbit and possibly in humans.