Cyclic pressure modulates endothelial barrier function.

Although numerous studies have documented the importance of mechanical forces in regulating many endothelial cell functions, the effects of these physical stimuli on endothelial barrier function are not well characterized. The present study used a custom-designed, cyclic pressure system to expose human umbilical vein endothelial cells (HUVECs) to physiologically relevant sinusoidal pressures and demonstrated that exposure to 140/100, but not to 60/20, mm Hg cyclic pressure at 1 Hz for 18 h resulted in a significant (p <.05) reduction in transendothelial permeability to albumin. Moreover, these cyclic pressure-selective changes in HUVEC barrier function occurred concomitantly with redistribution of intracellular tight junction protein zona occludens (ZO)-1 and reorientation of the F-actin cytoskeleton. In contrast, exposure of HUVECs to cyclic pressure had no affect on localization of adherens junctions proteins, vascular endothelial (VE)-cadherin, and beta-catenin. These results, therefore, provide the first evidence that select levels of cyclic pressure, a mechanical force pertinent to the hemodynamic vascular milieu, modulates the endothelial barrier function concomitant with an altered distribution of tight junction component, ZO-1.