Oscillatory shear alters endothelial hydraulic conductivity and nitric oxide levels.

This study addresses the role of nitric oxide (NO) and downstream signaling pathways in mediating the influences of oscillatory shear stress on the hydraulic conductivity (L(p)) of bovine aortic endothelial cell (BAEC) monolayers. Exposure of BAEC monolayers to 20 dyne/cm2 steady shear stress for 3 h induced a 3.3-fold increase in L(p). When an oscillatory shear amplitude of 10 dyne/cm2 was superimposed on a steady shear of 10 dyne/cm2 to produce a non-reversing oscillatory shear pattern (10+/-10 dyne/cm2), L(p) increased by 3.0-fold within 90 min. When the amplitude was increased to 15 dyne/cm2, resulting in a reversing oscillatory shear pattern (10+/-15 dyne/cm2), the increase in L(p) over 3 h was completely suppressed. Twenty and 10+/-10 dyne/cm2 induced 2.9- and 2.6-fold increases in NO production above non-sheared controls, respectively, whereas 10+/-15 dyne/cm2 stimulated a 14-fold increase in NO production. The inhibition of L(p) with reversing oscillatory shear may be associated with alterations in cyclic guanosine monophosphate (cGMP) production downstream of NO which is up-regulated by reversing oscillatory shear, but is unaffected by steady shear.