Preservation of endothelial cells in excised rat carotid arteries. Effects of transmural pressure and segment length.

When arteries are excised, they collapse and shorten spontaneously, which can result in damage to the endothelium. To determine if an intact endothelial cell layer could be preserved in excised vessels, we isolated and cannulated rat carotid artery segments (in situ length, Lis, 10-20 mm) at both ends while maintaining both transmural pressure (70 mm Hg) and Lis, while either transmural pressure or Lis, or after allowing vessel collapse and shortening (n = 4 vessels per treatment). After each treatment, vessel segments were perfused with fixative and stained with AgNO3 to visualize endothelial cells. The amount of endothelial cell loss was quantified using stereological analysis of video microscopic images of the luminal surface. Results demonstrated that maintenance of both Lis and transmural pressure minimized endothelial cell denudation (1.6 +/- 0.9%); permitting the vessel to collapse and shorten resulted in the greatest loss of endothelial cells (59.4 +/- 13.2%); and maintenance of either pressure or Lis resulted in intermediate endothelial cell loss (13-30%). We conclude that the spontaneous collapse and shortening that normally accompany the excision of arterial segments result in substantial endothelial cell loss, which can be virtually eliminated with the maintenance of transmural pressure and vessel segment length. These findings have implications for surgical and experimental procedures requiring intact endothelium.