The phosphoinositide turnover of vascular smooth muscle cells is influenced by fish oil.

As the phosphoinositide cycle and high serum levels of low-density lipoprotein cholesterol may be involved in the pathogenesis of both hypertension and atherosclerosis, the effect of fish oil on low-density lipoprotein stimulation of phosphoinositide metabolism was studied in cultured rat vascular smooth muscle cells. Low-density lipoprotein-stimulated synthesis of inositol trisphosphate decreased to 5-48% of control values in vascular smooth muscle cells treated for 4 weeks with either fish oil or n-3 eicosapentaenoic acid (EPA), the active ingredient of fish oil. In addition, low-density lipoprotein-induced biosynthesis of thromboxane A2 was reduced by 50% in vascular smooth muscle cells precultured with either fish oil or EPA. Thus, our results may explain the mechanisms by which fish oil exerts its beneficial effects on both atherosclerosis and hypertension.