Thromboxane A(2) fails to induce proliferation of smooth muscle cells enriched with eicosapentaenoic acid and docosahexaenoic acid

(T)hromboxane A(2) (TXA(2)) released from aggregating platelets and injured vessel wall stimulates smooth muscle cell proliferation, which may contrib ute to the development of vascular lesion formation after percutaneous tran sluminal coronary angioplasty. Polyunsaturated fatty acids (n-3) present in the fish oils have been shown to have anti-atherosclerotic effects. In vie w of this, we examined the effect of eicosapentaenoic acid (EPA) and docosa hexaenoic acid (DHA), the active ingredients of fish oils on TXA(2) induced smooth muscle cell proliferation. To find out the specificity of these fat ty acids we used gamma-linolenic acid (n-6) and oleic acid (n-9) as control s. It was found that TXA(2) failed to stimulate proliferation of smooth mus cle cells preloaded with EPA or DHA but not with gamma-linolenic acid or ol eic acid. Further, when smooth muscle cells were preloaded with both EPA an d DHA, they acted together in preventing the TXA(2) induced smooth muscle c ell proliferation. These results demonstrate that one of the mechanisms by which fish oils may prevent neointima formation is by making smooth muscle cells less responsive to TXA(2) induced proliferation of smooth muscle cell s.