ROLE OF MARGINAL STRESS FIBERS FORMED IN THE RAT VASCULAR ENDOTHELIAL-CELLS

Fluorescence cytochemistry using en face preparations of rat vascular endothelial cells (ECs) revealed the localization of actin. fibronecti n (FN) and fibronectin receptor (FNR) along not only central stress fi bers (SFs) but also the cell margins. Electron microscopy showed very close proximity between the topographical distribution of intracellula r microfilament bundles and that of subendothelial FN in the EC margin s. Therefore, these basal and marginal actin cables may be comparable to the well-established central SFs present in ECs. Formation of the c entral SFs was induced in ECs or mesothelial cells in response to tens ion, by which their cellular integrity seems to be effectively maintai ned. However, even when central SF formation was inhibited by cytochal asin D, the ECs with marginal SFs showed high resistance to mechanical tension, whereas mesenteric mesothelial cells having no such fibers e asily lost their integrity. Thus, together with central SFs, the margi nal SFs characteristic of rat vascular ECs may play an essential role in strengthening cell-matrix adhesion.