Regression of Atherosclerosis

Abstract

Regression of experimental atherosclerosis has been introduced by some investigators. This paper represents the regression of atherosclerosis in the respect of vascular permeability, aging of aorta and the reversibility of early atherosclerotic lesions (e. g. fatty streak, cloudy thickening and mural thrombi).Ultrastructurally, aortic intima consists of three layers and increased in thickness in the aged group (over 60yrs). In this group, most remarkable change is thickening of the inner layer of intima, connective tissue layer. There are atrophy of intimal myogenic cells, extracellular basement membrane-like material deposits and proliferation of disrupted fibrillar elastic and collagen fibers. The result shows the severity of regression of atherosclerotic lesions in such an aged group because of its morphological findings.Vascular permeability of human common carotid artery by means of 1% ferric citrate infusion is presented. In the aged group, ferric citrate is condensed in the superficial zone of intima and is caught in the elastic lamina of media. It seems to be thought as the decrease of whole vascular permeability. In the advanced atherosclerotic lesions, there is a lowering of ferric citrate permeability. On the other side, initial lesions of atherosclerosis shows high vascular permeability. These findings of vascular permeability reveal that there must be complicated circumstance behind the regression of atherosclerosis.Early lesions of atherosclerosis seem to be all reversible when the lesions are not severe and the lack of irreversible destruction of intimal structure and fibro-cellular proliferation.Experimental aortic atherosclerosis of rabbit induced by cholesterol feeding for 8 weeks showed a tendency to the depletion of aortic fatty lesion 6 weeks after returning to the basal diet.And the author observed the process of organization of experimental aortic thrombi in rabbit. This complete results of experimental atherosclerosis should be reported in detail afterwards.