Alteration of endothelial cell surface morphology after experimental aortic coarctation

The aortic arch of normal swine shows areas of enhanced permeability to proteins which take up intravenously-injected Evans blue (Old blue areas) and adjacent areas of lesser permeability which do not take up dye (white areas). Following 4 wk of coarctation at the ductus scar level (60% occlusion), former white areas demonstrate Evans blue uptake (New blue areas). Microscopic quantitation showed that endothelial cells in new blue areas had a significantly (p less than .001) altered axial ratio (cell length to width) of 1.41 +/- .04 and mean surface area of 704 +/- 35 mu2 compared to the same area in controls (axial ratio 3.30 +/- .09, mean area 545 +/- 38), but were not significantly different from old blue areas (axial ratio 1.39 +/- .03, area 741 +/- 40). Both new and old blue areas contained three times as many dead or injured cells as white areas in controls. Electron microscopy revealed that New blue area endothelium was similar to that of old blue areas, and that focal denudation and platelet adherence was sometimes present in both areas. The results support the belief that the altered characteristics of spontaneous blue areas are due to hemodynamics effects, and demonstrate that arterial occlusion increases endothelial cell surface area and alters cell orientation relative to blood flow, as well as enhancing injury. Such endothelial alterations could potentiate the disease process in partially-occluded arteries.