Hemodynamic-force-induced difference of interendothelial junctional complexes.

1. The flow divider of the brachiocephalic branching of the rabbit aorta had both high and low shear stress regions, each of which was covered by endothelial cells with low and high permeability respectively, even in normolipidemic intact rabbits. When rabbits were placed on an atherogenic diet, low shear regions were the most vulnerable for lipid deposition, but the high shear regions were spared from deposition. 2. A freeze fracture study revealed that high shear regions both at the brachiocephalic branching and in the surgically coarctated abdominal aorta of rabbits had a more common appearance of zonular type tight junctions. Mean low shear regions had more macular and less zonular type. 3. Cultured porcine aortic endothelial cells exposed to laminar 30 dyn/cm2 shear stress in a flow chamber developed ridges of membranous protein particles at the cell-cell contact. 4. Increases of magnitude and duration of exposure to shear stress enhanced the structure of the protein ridge of the tight junction and immunohistochemical expression of proteins associated with both tight and adherens junctions.