INTERACTIONS BETWEEN CULTURED BOVINE ARTERIAL ENDOTHELIAL AND SMOOTH-MUSCLE CELLS - STUDIES ON UPTAKE AND DEGRADATION OF LOW-DENSITY LIPOPROTEINS BY SMOOTH-MUSCLE CELLS

This study was designed to investigate the effects of substances relea sed from non-injured and injured bovine arterial endothelial cells on I-125-low density lipoprotein uptake and degradation by smooth muscle cells in culture. It was demonstrated that endothelial cell-released n on-dialysable (molecular weight cut off 12-14000) substances significa ntly stimulated I-125-low density lipoprotein uptake and degradation b y smooth muscle cells. Endothelial cell-released dialysable substances and endothelin-l did not cause this stimulation. The increase in I-12 5-low density lipoprotein uptake and degradation by smooth muscle cell s could be dissociated from cell proliferation. However, in endothelia l cell-smooth muscle cell co-culture I-125-low density lipoprotein upt ake and degradation by smooth muscle cells were not stimulated. Injury to endothelial cells by lipid-soluble smoke particles or ultraviolet light, which reduced total cellular protein by 15-25%, enhanced the en dothelial cell release of the substances stimulating I-125-low density lipoprotein uptake. The results are discussed in relation to atheroge nesis.