Effect of aspirin on intimal hyperplasia and cholesterol uptake in experimental bypass grafts

The effects of aspirin on intimal and medial smooth muscle cell proliferation and cholesterol uptake in experimental bypass grafts were examined in a hypercholesterolemic canine model. Ten animals receiving a 2% cholesterol diet served as controls, while a further 10 animals received the same diet and 160 mg aspirin daily. Segments of external jugular vein were implanted between bilaterally divided femoral arteries. Tissue cholesterol and intimal and medial thicknesses were measured at six weeks. Graft cholesterol had increased 1.7 mumol/g at six weeks in the control group but only rose by 0.28 mumol/g in animals receiving aspirin (P less than 0.002). Intimal and medial smooth muscle cell proliferation was evident in all experimental bypass grafts and was unaffected by aspirin. It is concluded that cholesterol uptake and smooth muscle proliferation may be controlled by different mechanisms, and that aspirin reduces cholesterol uptake but does not prevent smooth muscle cell proliferation in experimental bypass grafts.