Albumin permeability across endothelial monolayers under long-term shear stress

Endothelial cells lining the inner surface of blood vessels regulate the exchange of molecules between the blood and the vessel wall. This study investigates the effect of longterm shear stress on macromolecule permeability across endothelial monolayers. In vitro system to measure transendothelial permeability to tetramethylrhodamine conjugated albumin under shear stress was developed. The temporal variation in albumin permeability under 1 Pa and 4 Pa over 48 h was quantified using a fluorescence spectrophotometer. At 4 Pa, albumin permeability did not show a statistical significant change over 48 h. Under shear stress of 1 Pa, the average albumin permeability between 12 and 30 h was 2.5-fold higher than the average between 0 and 6 h. Under shear stress of 1 Pa, the average albumin permeability between 36 and 48 h was 1.8-fold higher than the average between 12 and 30 h. These results show that both the magnitude of, and the length of exposure to, shear stress regulate transendothelial permeability.