Relaxation effects of ligustilide and senkyunolide A, two main constituents of Ligusticum chuanxiong, in rat isolated aorta

Ligusticum chuanxiong Hort. (Umbelliferae) is a widely prescribed traditional Chinese medicinal herb for cardiovascular diseases in China. However, the cardiovascular actions of ligustilide and senkyunolide A, two of the most abundant Ligusticum chuanxiong constituents, have yet to be examined. The objective of the present study was to investigate the vasorelaxation effects of ligustilide and senkyunolide A and their underlying mechanisms in rat isolated aorta. Both constituents had similar relaxation potencies against contractions to 9,11-dideoxy-9α,11α-methanoepoxyprostaglandin F2α, phenylephrine, 5-hydroxytryptamine and KCl. Their vasorelaxation effects were not affected by endothelium removal, the adenylate cyclase inhibitor 9-(tetrahydro-2-furanyl)-9H-purin-6-amine, the soluble guanylate cyclase inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, or the non-selective K+ channel blocker tetraethylammonium. This is the first report to demonstrate the vasorelaxation activities of ligustilide and senkyunolide A in contractions to various contractile agents in rat isolated aorta. The underlying mechanisms await further investigations.