Low-dose aspirin does not attenuate platelet aggregation or atherosclerosis in miniature swine but decreases production of aortic wall prostacyclin

The objectives of this study were to determine if, and at what dose, aspirin could attenuate atherosclerosis in hypercholesterolemic Yucatan miniature swine, and to determine the influence of aspirin on aortic wall prostacyclin production and platelet aggregation. 30 Yucatan miniature swine (age 3 months) were fed either regular diet (RD), atherogenic diet (AD), or AD plus one of four aspirin dosages (2,4,8, or 16 mg/kg/d) for 6 months. The extent of atherosclerotic lesions in the abdominal aorta and coronary arteries was evaluated by sudanophilic staining and histological grading using Stary's classification, respectively. Aortic wall production of prostacyclin (PGI₂) and platelet aggregation were assessed. Lesions were similar among the AD groups (45.3 ± 4.3%) and significantly higher than RD (1.4 ± 0.4%). PGI₂ production was significantly lower (p < 0.05) in all aspirin-treated groups. Platelet aggregation was not affected by treatment. It is concluded that the range of aspirin dosages (2-16 mg/kg/d) does not attenuate the development of atherosclerosis.