['Our purpose was to determine whether mechanical deformation alters in vitro effects of plasma from patients with preeclampsia on endothelial cell function to produce a paradigm similar to the in vivo disease state.', 'The effects of 2% plasma from 12 patients with preeclampsia and 12 normal pregnant women on prostacyclin, nitric oxide, and endothelin production by cultured endothelial cells were measured in the presence or absence of cyclic stretch and laminar shear stress.', 'In the absence of mechanical stress plasma from patients with preeclampsia resulted in greater prostacyclin and nitric oxide production (but no change in endothelin production) compared with plasma from normal pregnant women. Cyclic stretch did not affect prostacyclin or endothelin production but produced similar increases in nitric oxide production in cells exposed to plasma from the two groups. Shear stress markedly increased prostacyclin and nitric oxide production (but did not alter endothelin production). In the presence of shear stress there were no differences in production rates of nitric oxide or prostacyclin between cells exposed to plasma from the two groups.'] Does mechanical stress eliminate the effects of plasma from patients with preeclampsia on endothelial cells?