Inhibitory Effect of Geraniin on Agonist-Induced Vascular Contractility via Calcium Desensitization-Related Pathways

Geraniin is an ellagitannin derived from the rinds of Nephelium lappaceum and exhibits a wide range of biological functions.In this study, we investigated the effect of geraniin on vascular contractility and elucidated its underlying mechanisms.Isometric contractions of endothelium-denuded aortas from male rats were evaluated along with molecular assays.Geraniin significantly attenuated contractions induced by fluoride, a thromboxane A 2 mimetic, and phorbol ester, suggesting a potential antihypertensive effect through mechanisms independent of endothelial nitric oxide synthesis.Furthermore, geraniin reduced fluoride-induced phosphorylation of MYPT1 and phorbol ester-induced phosphorylation of ERK1/2, indicating that its vasorelaxant effect involves the inhibition of Rho-kinase and MEK activity.These findings provide mechanistic insights into the calcium desensitization pathways that contribute to geraniin-induced vascular relaxation, regardless of endothelial function.