Carotid proliferative plaque formation in a canine model of chronic hypertension.

Background: There are few reports describing arterial plaque formation induced by hypertension alone. The aim of this study was to establish a canine model of chronic hypertension and investigate carotid plaque development. Methods: Ten beagles were studied; 5 underwent bilateral renal artery constriction via a novel vascular clip, and 5 sham-operated animals served as controls. Systolic blood pressure (SBP), diastolic blood pressure (DBP), lipid values, the intima-media thickness, and the carotid artery plaque score were investigated during 1 year after placement of the clips. Results: The mean SBP and DBP over time were significantly greater in the constriction group (P < 0.001 for SBP, P < 0.01 for DBP). There were no significant differences in blood lipid levels or other biochemical parameters. Carotid plaques were demonstrated at 4 months postoperation in the constriction group; and in the constriction group, intima-media thickness became significantly greater at 4 months (P < 0.05), and plaque scores became significantly higher at 8 months (P = 0.034) after clip placement. Carotid stenosis was proved by digital subtraction angiography 1 year after clip placement, and histological examination revealed that the plaques were mainly comprised of smooth muscle cells, proteoglycans, and collagen fibers, but few macrophages and little lipid. Conclusions: Carotid proliferative plaques were developed in a canine model of chronic hypertension induced by a novel vascular clip. The plaques were mainly comprised of smooth muscle cells, proteoglycans, and collagen fibers.