Vascular endothelial stress fibres: their potential role in protecting the vessel wall from rheological damage.

Confluent monolayers of endothelial cells from the umbilical vein were exposed to two different levels of shear stress, 2 dyn/cm2 (low arterial value) and 0.5 dyn/cm2 (venous levels) for 60 and 120 min. A dramatic increase in stress fibres was only observed at arterial levels of shear stress while venous levels of shear stress had no significant effect on the stress fibre system. In view of our observation that the stress fibres can contract it is suggested that the induced stress fibres can exert tension to resist the shear forces of blood flow and thus prevent the endothelium from hydrodynamic damage or detachment. Thus stress fibre formation may be an important mechanism to prevent the vascular wall from pathologic stimuli which are thought to initiate arteriosclerosis.