Endothelium-dependent vasodilatation effects of the essential oil from Fructus Alpiniae Zerumbet (EOFAZ) on rat thoracic aortic rings in vitro

Fructus Alpiniae Zerumbet (FAZ) is an herb widely used to treat vascular disorders in Guizhou province, China, the essential oil has been identified as one of it vasodilation effect active components, and especial, the composition was significantly difference from the leaves. Vasodilation effects and mechanism of essential oil from FAZ (EOFAZ) were investigated. The EOFAZ showed significant vasodilation effect on endothelium-with rat thoracic aortic rings preincubated with norepinephrine (NE, 1.0 μM) or KCl (60 mM) in a concentration-dependent manner (1.14-72.96 μg/ml). The non-selective nitric oxide synthase inhibitor l-NAME, as well as the soluble guanylate cyclase inhibitor MB, attenuated the relaxation of EOFAZ in endothelium-intact rat thoracic aortic rings. However, there were not significantly affected the vasodilation effects pretreated with cyclooxygenase inhibition by indomethacin (Indo) or β-noradrenergic inhibition by propranolol (Prop). The present results first demonstrated that vasodilation effect of EOFAZ depending upon the endothelium and concentration, and the mechanism involvement of NOS-cGMP system. In contrast, prostacyclin and β-adrenoceptor may not be associated with EOFAZ-induced vasorelaxation.