Morphological functional changes of aortic endothelium during different types of hypertension.

In rats, ligature of the aorta between the renal arteries produces hypertension which in the early phase (6-7 days) is associated with elevated plasma renin content, and later (40 days) is associated with low plasma renin. During the early phase, the endothelium of the aorta shows elevated permeability to HRP, endothelial cells are hypertrophic and contain bundles of actin microfilaments. During the late phase, permeability to HRP is normal, the endothelial cells are flat and do not contain bundles of microfilaments. Probably the endothelial cells of aorta react in different ways to various hypertensive stimuli and/or adapt to high levels of blood pressure.