Relationship between energy-dependent macromolecule uptake and transport granules in the endothelial cells affected by wall shear stress

The purpose of this study is to reveal (1) the energy dependence of albumin uptake into endothelial cells, and (2) the effect of shear stress on the albumin uptake area and the its content per unit area. The uptake of the fluorescent labeled albumin (tetramethylrhodamine isothiocyanate conjugated albumin, TRITOalbumin) was visualized with a confocal laser scanning microscope. The uptake into the endothelial cells is inhibited completely at 4°C or by 1 μM FCCP, that is a potent energy metabolism inhibitor. This result indicates that the albumin uptake is an energy-dependent, active transport. After 48 hour exposure to shear stress to the endothelial cells, the albumin uptake area and the albumin content per unit area were changed. At 10 dyn/cm², at 5 μm the uptake area increases by 363% and the albumin content per unit area increases by 192%. At 60 dyn/cm², at 3 μm the uptake area decreases by 21% and the albumin content per unit area decreases by 54%. It is, therefore, considered that the effect of shear stress on the uptake area is more influential than that on the albumin content per unit area. We conclude that endothelial cells affected by sher stress change the albumin uptake function and especially the cells change the uptake area.