Chemical changes in the arterial wall during regression of atherosclerosis in monkeys.

Changes of arterial wall lipid and connective tissue components were studied under various regression regimes on experimental high fat-cholesterol diet induced atherosclerosis in non-human primates. Levels of plasma lipids and aorta tissue lipids were closely related, while an inverse relationship between plasma cholesterol levels was noted with the ratio of aorta tissue free/ester cholesterol. Although the total content of glycosaminoglycan increased slightly with increasing disease, changes of individual glycosaminoglycans were most closely related to the severity of aorta atherosclerosis associated with both induction and regression of disease. With increasing atherosclerosis hyaluronic acid tended to decrease, while chondroitin sulfates decreased. Heparan sulfate decreased considerably with increasing severity of atherosclerosis. Consequently, regression regimens reducing the severity reversed the glycosominoglycan changes. Withdrawal of the dietary stimulus and cholestryamine produced the greatest reversal of atherosclerosis. In contrast, D-thyroxine treatment resulted in severe aorta atherosclerosis comparable to controls receiving no treatment. The effectiveness of regression depends on favorably altering plasma lipids but without adversely affecting the arterial wall structural elements.