Effects of chronic aortic coarctation on atherosclerosis and arterial lipid accumulation in the Watanabe hereditary hyperlipidemic (WHHL) rabbit.

The effects of high blood pressure on atherosclerosis were examined in the Watanabe heritable hyperlipidemic (WHHL) rabbit. For this purpose, the subdiaphragmatic aorta of rabbits was partially ligated (coarctation) to increase blood pressure. Atherosclerosis was assessed 4 months later by morphometric analyses and quantitation of arterial lipids. Results were compared to control WHHL rabbits with matched plasma triglycerides and cholesterol levels. A marked increase in atherosclerotic lesions was observed in the thoracic aorta of the hypertensive rabbits without qualitative changes in its morphometric features. The cross sectional area of the atherosclerotic plaques of the ascending and descending aorta in the hypertensive rabbits was two- and six-times larger than in normotensive rabbits, respectively. Lesions represented 12.0% +/- 3.5% of the total medial cross sectional area of the descending aorta of normotensive rabbits, versus 45.0% +/- 5.7% in hypertensive rabbits. No lesions were observed downstream of the coarctation in hypertensive rabbits, nor in the normotensive rabbits. Accumulation of cholesterol and choline-containing phospholipids in the descending aorta of hypertensive rabbits was increased 3.2- and 1.5-fold, respectively, when compared to normotensive rabbits. Hypertension did not change the unesterified cholesterol/total cholesterol and sphingomyelin/lecithin + lysolecithin molar ratios. In conclusion, chronic coarctation enhances the atherosclerotic response in WHHL rabbits in the high blood pressure compartment, and reduces the variability of this response.