The essential oil of Citrus bergamiaRisso induces vasorelaxation of the mouse aorta by activating K plus channels and inhibiting Ca2+influx

Abstract

Objectives The aim of this study was to explore the effect of the essential oil of Citrus bergamiaRisso (bergamot) on mouse blood vessels and to analyse the mechanism of this effect from a pharmacological perspective. Methods We investigated the effect of bergamot essential oil (BEO) on vascular tonus during contraction of mouse aorta induced by prostaglandin F2 (PGF2) or noradrenaline (norepinephrine). Key findings In mouse aortic rings, BEO (0.01, 0.1 and 0.2% v/v) reduced contraction in a dose-dependent manner, and relaxed the vascular tonus induced by PGF2. No significant difference in the extent of vasorelaxation induced by 0.1% (v/v) BEO was evident when rings with intact endothelium and endothelium-denuded rings were compared. When aortic rings were suspended in a medium that was Ca2+-free but contained 80mm KCl, addition of CaCl2 (1, 2.5 or 5mm) induced contraction in a dose-dependent manner. However, addition of Ca2+ after incubation of the rings with BEO strongly suppressed CaCl2-induced contraction. Further, the K+-channel blocker tetraethylammonium chloride partially blocked BEO-induced vasorelaxation. Conclusions Our findings suggest that BEO may induce endothelium-independent vasorelaxation by regulating the vascular tone of smooth muscle. Activation of K+ channels and inhibition of Ca2+ influx may be involved in vasorelaxation of mouse aorta elicited by BEO.