Effect of fluid flow on membrane fluidity in endothelial cells

Human umbilical vein endothelial cells were sheared in a parallel flow chamber to study the effect of fluid flow on membrane fluidity. Steady flow was produced by a flow loop for wall shear stresses⩾6 dy/cm² and by a syringe pump for lower shears. Pulsatile flow was created by a system including a syringe driven by a motor and a set of one-way valves. The fluorescent dye merocyanine 540 was used to monitor phospholipid packing of the endothelial cells subjected to steady and pulsatile fluid flow. Sheared cells bound up to 60% more dye than the stationary controls (p<0.01). This suggests that fluid flow increases the membrane fluidity of the endothelial cells