|Budget Amount *help
¥1,200,000 (Direct Cost : ¥1,200,000)
Fiscal Year 1992 : ¥500,000 (Direct Cost : ¥500,000)
Fiscal Year 1991 : ¥700,000 (Direct Cost : ¥700,000)
Adhesion between endothelial cells (ECs) and between ECs and the basal lamina is of critical importance for the function of the vascular endothelium. We studied the cell-substrate adhesion mechanism, especially the one which employs stress fibers (SFs). of ECs in the chick aorta and mesenteric artery. The ultrastructure of SFs and adhesion plaques in situ was identical to those seen in cultured cells. Fibronectin (FN) fibrils, identified by electron microscopic immunocytochemistry, were seen attached to the basal cell surface at the adhesion plaque. By morphology, adhesion plaques of in situ cells were identical to those of in vitro cells, suggesting that ECs in blood vessels employ the same adhesion mechanism as cultured cells do when attaching to the substrate. In large vessels, FN fibrils were oriented in the direction of blood flow. We found that the axial FN organization depended on the presence of axially aligned SFs. As the vessel diameter decreased, so did both the extent of SF development and the axial FN organization. In fact, the axial FN organization was not observed without axially organized SFs. In rapidly growing chick embryos, ECs elongation in the direction of blood flow took place first, followed by SF development and then by FN alignment. To better analyze the flow effect on the SF and the FN organization in the endothelium, we are now using a fluid flow chamber in which ECs can be cultured under known levels of fluid shear stress. The chamber allows us to use interference reflection microscopy to follow the behavior of adhesion plaques of Ecs under fluid flow. Results of these studies are now emerging.