It is well known that vascular endothelial cell (EC) migration plays a major role in regeneration of the injured endothelium and also that smooth muscle cell (SMC) migration is the important step for atheromatous plaque formation. In the present study, we investigated the effects of cholesterol and eicosapentaenoic acid (EPA) on bovine carotid artery EC and SMC migration using the modified Boyden chamber technique. The migration activity of the cholesterol-enriched ECs loaded with cholesterol-rich liposomes was significantly suppressed, whereas that of the cholesterol-enriched SMCs was enhanced. Next, we examined the effects of EPA pretreatment on the migration of both cell types. When ECs and SMCs were treated with EPA (5 micrograms/ml) for 2 days, the EPA content increased from 0.55 +/- 0.04% to 11.72 +/- 0.19% and 1.22 +/- 0.09% to 9.69 +/- 0.07% in cellular phospholipids, respectively. Although pretreatment of the ECs with EPA caused a significant increase in serum-induced cell migration, pretreatment of SMCs had no effect. If both cell types were concomitantly pretreated with EPA and cholesterol-rich liposomes, EPA abolished the effects of cholesterol on the migration of both cell types, but did not affect the content of cholesterol in both cells. These data indicate the possibility that EPA counteracts the atherogenic effect of cholesterol on EC and SMC migration.