Inhibition by docosahexaenoic acid of receptor-mediated Ca2+ influx in rat vascular smooth muscle cells stimulated with 5-hydroxytryptamine

The effect of docosahexaenoic acid treatment on intracellular Ca2+ dynamics in rat vascular smooth muscle cells stimulated with 5-hydroxytryptamine (5-HT) has been investigated in order to elucidate one of the mechanisms for its beneficial effect on cardiovascular disorders. The treatment of cells with 30 muM docosahexaenoic acid for 2 days inhibited an increase in intracellular Ca2+ concentration induced by 5-HT (10 muM) and a depolarizing concentration of KCI (80 mM). Docosahexaenoic acid treatment significantly inhibited divalent cation influx stimulated by 5-HT and KCI, as measured by Mn2+ quenching method, whereas had no effect on 5-HT-induced Ca2+ release from the internal stores. Docosahexaenoic acid treatment also significantly inhibited 5-HT receptor-mediated Ca2+ influx through Ni2+-insensitive channels that were distinct from store-operated channels. These results suggest that the specific inhibition of intracellular Ca2+ dynamics in vascular smooth muscle cells may contribute to the beneficial properties of docosahexaenoic acid on cardiovascular disorders. (C) 2001 Elsevier Science B.V. All rights reserved.