Atherosclerosis and endothelium. Part II. Properties of aortic endothelial and smooth muscle cells cultured at various ambient pressures.

Human aortic endothelial cells and smooth muscle cells (SMCs) were cultured at various ambient pressures and their properties were examined. The following results were obtained. 1) Endothelial cells were damaged when cultured at higher ambient pressures of 80 and 160 mmHg. This left cellular islands with central confluence showing no evident growth because of strong contact inhibition. 2) Aortic endothelial cells released high levels of prostacyclin, with significantly elevated release at higher ambient pressures, while intimal SMCs released a small amount of prostacyclin, and medial SMCs a minimal amount. 3) Prostacyclin release by aortic endothelial cells was inhibited in the presence of low concentrations of linoleic acid hydroperoxide (LAHO). Intimal and medial SMCs, however, showed no LAHO inhibition. These results indicate that the properties of both endothelial cells and SMCs vary according to in vitro and probably in vivo conditions. Their specific roles in the pathogenesis of various vascular disorders including atherosclerosis should be carefully considered.