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.