Hypoxia and the Arterial Surface

Abstract

Adult rabbits were exposed to reduced oxygen environments (12% to 14%) for 72 hours by dilution of room air with compressed nitrogen. Aortic surfaces were examined by scanning electron microscopy. Control animals were similiarly processed at normal levels of oxygen. Patterns of linear folds running in the direction of blood flow were observed in control animals, with endothelial cells tightly attached to the underlying internal elastic membrane. Hypoxic arterial surfaces showed grossly distorted linear folds, with swollen and convoluted endothelial surfaces which obscured the spaces between the folds while preserving the plicate organization. These changes resemble the reported effects of moderate carbon monoxide exposure. Accumulation of subendothelial fluid appeared to channel the length of the fold, and to present a swollen endothelial surface susceptible to injury by the pulsatile blood flow.