Fibrinogen degradation products influence PGI2 synthesis by cultured porcine aortic endothelial and smooth muscle cells

The synthesis of prostaglandin I2 (PGI2) was found to decrease with age in cultured, porcine aortic endothelial cells. Arachidonic acid (AA)-induced PGI2 synthesis per cell at low cell density was higher than that at high cell density. PGI2 synthesis by cultured porcine aortic smooth muscle cells, without exogenous AA, was higher than that by cultured porcine aortic endothelial cells, while AA-induced PGI2 synthesis by cultured porcine aortic medial smooth muscle cells was lower than that by cultured endothelial cells. PGI2 synthesis by cultured smooth muscle cells incubated with fibrinogen degradation products (FDPs) for 24 h decreased. After incubation with FDPs for 24 h, AA-induced PGI2 synthesis by endothelial cells also diminished. These data suggest that PGI2 synthesis in the vascular wall is affected by FDPs, and that FDPs probably play an important role in the initiation of atherosclerosis.