Raised blood pressure and endothelial cell injury in rabbit aorta

The aim of this study was to examine whether raised blood pressure in rabbits was associated with increased aortic endothelial cell injury, compared to rabbits with normal blood pressure. In 25 randomly selected rabbits protruding aortic endothelial cells were quantified in scanning electron micrographs in standardized areas using a point-counting morphometric procedure. In thirteen animals a left renal artery stenosis was established; the other twelve were sham-operated. One week after operation, raised blood pressure occurred in most of the former animals and in some of the sham-operated as well. The prevalence of protruding endothelial cells was significantly higher in animals with elevated blood pressure. A zero-order correlation analysis between endothelial cell injury and blood pressure showed significant association in all sampled areas. When stenosis-operation vs. sham-operation was correlated with blood pressure, significant correlation occurred in samples from the lesser curvature of the aortic arch only. A multiple linear regression analysis with endothelial cell injury as dependent variable and blood pressures (systolic, diastolic, pulse and average) and type of operation as predictors did not change the conclusions. In the lesser curvature of the aortic arch and in the area just distal to the intercostal artery orifices, a much higher increase of protruding endothelial cells was seen compared with the area between intercostal artery orifices on the same side. Mechanical forces of the blood stream and increased stretching of the intima may possibly be factors in causing the increased endothelial cell injury in raised blood pressure.