Interaction between wall shear stress and circumferential strain affects endothelial cell biochemical production

The wall shear stress (WSS) of flowing blood and the circumferential strain (CS) driven by the pressure pulse interact to impose a dynamic force patte rn on endothelial cells (ECs) which can be characterized by the temporal ph ase angle between WSS and CS, a quantity which varies significantly through out the circulation. To study the interaction of WSS and CS on endothelial production of vasodilators (prostacyclin and nitric oxide) and a vasoconstr ictor (endothelin-1), bovine aortic ECs were cultured on the inner surface of compliant tubes and subjected to various flow conditions: steady shear ( 10 dyn/cm(2)), oscillatory shear (10 +/- 10 dyn/cm(2), rigid tube), and osc illatory shear (10 +/- 10 dyn/cm(2)) with CS (8%) either in or out of phase with shear. The 4-hour production rates of vasoactive agents show that ste ady shear stimulates the highest production of vasodilators whereas oscilla tory shear stimulates the highest vasoconstrictor production. The addition of CS in concert with oscillatory shear enhances the production of vasodila tors a nd inhibits the production of vasoconstrictors, and this effect is m odulated by the phase angle between WSS and CS. These data suggest that the interactions of WSS and CS are important in vascular regulation and remode ling. Copyright (C) 2000 S. Karger AG, Basel.