Actin filament bundles comparable to stress fibers were found exclusively in vascular endothelial cells, oriented parallel to blood flow in high-velocity regions.
Observational
Actin filament stress fibers exist in vivo in vascular endothelial cells and align with blood flow, likely helping cells withstand hemodynamic stress.
Fluorescence microscopy with 7-nitrobenz-2-oxa-3-diazole phallacidin was used to survey vertebrate tissues for actin filament bundles comparable to the stress fibers of cultured cells. Such bundles were found only in vascular endothelial cells. Like the stress fibers of cultured cells, these actin filament bundles were stained in a punctate pattern by fluorescent antibodies to both alpha-actinin and myosin. The stress fibers were oriented parallel to the direction of blood flow and were prominent in endothelial cells from regions exposed to high-velocity flow, such as the left ventricle, aortic valve, and aorta. Actin bundles may help the endothelial cell to withstand hemodynamic stress.
Wong et al. (1983) reported an observational. Fluorescence microscopy was evaluated on Presence and orientation of actin filament bundles. Actin filament bundles comparable to stress fibers were found exclusively in vascular endothelial cells, oriented parallel to blood flow in high-velocity regions.