Endothelial albumin permeability is shear dependent, time dependent, and reversible

Altered permeability of vascular endothelium to macromolecules may play a role in vascular disease as well as vascular homeostasis. Because the shear stress of flowing blood on the vascular wall is known to influence many endothelial cell properties, an in vitro system to measure transendothelial permeability (P(e)) to fluorescein isothiocyanate conjugated bovine serum albumin under defined physiological levels of steady laminar shear stress was developed. Bovine aortic endothelial cells grown on polycarbonate filters pretreated with gelatin and fibronectin constituted the model system. Onset of 1 dyn/cm² shear stress resulted in a P(e) rise from 5.1 ± 1.3 x 10^-6 cm/s to 21.9 ± 4.6 x 10^-6 cm/s at 60 min (n = 6); while 10 dyn/cm² shear stress increased P(e) from 4.8 ± 1.5 x 10^-6 cm/s to 50.2 ± 6.8 x 10^-6 cm/s at 30 min and 49.6 ± 8.9 x 10^-6 cm/s at 60 (n = 9). P(e) returned to preshear values within 120 and 60 min after removal of 1 and 10 dyn/cm² shear stress, respectively. The data show that endothelial cell P(e) in vitro is acutely sensitive to shear stress.