Elevated levels of plasma LDL have been correlated with morphological endothelial damages, e.g. reduced antithrombogenity of endothelial cells. Numerical and functional defects of endothelial cells ...probably influence the necessary separation of blood fractions from subendothelial tissues in a negative sense. In order to describe an imaginable endothelial dysfunction with respect to LDL transport we examined human umbilical venous endothelial cells (HUVEC) in culture under physiological flow conditions. HUVEC in culture after incubation with a LDL concentration of 100 micrograms/ml medium were exposed to defined levels of physiological shear stress, fixed with formalin and stained with oil-red-O. After documentation of oil-red-O staining with a photomicroscope, the amount of stain has been characterized semiquantitatively with the help of an image-analysis system (IBAS II/Zeiss). HUVEC not exposed to shear stress only showed a marginal oil-red-O staining at the cell surface. If they were exposed to shear stress of 0.5 dyn/cm2 they showed in orthogonal view an average increase of 1.3%, in cross-sectional view an average increase of 0.3%. HUVEC exposed to shear stress of 2.5 dyn/cm2 showed in orthogonal view an average increase of 4.6%, in cross-sectional view an average increase of 8.7%.
