Repair in arterial tissue. Morphological and biochemical changes in rabbit aorta after a single dilatation injury.

Abstract

Male albino rabbits were subjected to a single mechanical dilatation of the descending thoracic aorta with a balloon catheter. The animals were killed 3, 6, 14, 30, and 60 days later. Between the sixth and the fourteenth days after injury, all the aortas which had been dilated developed severe, gross arteriosclerosis. Microscopic examination showed destruction and degeneration in the form of necrosis and calcification as well as regeneration and repair including new formation of cells, intercellular substance, and fibers. Biochemical and histochemical analyses revealed an early increase in hyaluronic acid and water followed by an increase in chondroitin-4, 6-sulfate and a later increase in heparan sulfate, dermatan sulfate, and collagen. These alterations were related to the focal lesions in the aortic wall. The permeability of the aorta to 125 I-albumin increased to a maximum 3 days after the dilatation, whereupon it decreased rapidly. The alterations were interpreted as nonspecific processes of repair in the vascular connective tissue. The pronounced dependence of the alterations on the time elapsed after injury must be considered in the study of vascular diseases where injury and repair may be involved.