| Summary: | Alkaloids derived from plants have shown great medicinal benefits, and are often reported for their use in cardiovascular disease management. <i>Aristotelia chilensis</i> (Molina) Stuntz (Maqui) has shown important medicinal properties in traditional useage. In this study, we evaluated the effect of the indole-alkaloid aristoteline (ARI), isolated from leaves of Maqui, on vascular reactivity of isolated aortic rings from normotensive rats. ARI induced relaxation (100%) in a concentration-dependent manner in intact or denuded-endothelium aortic rings pre-contracted with phenylephrine (PE; 1 μM). However, a specific soluble guanylyl cyclase inhibitor (ODQ; 1 μM) significantly reduced the relaxation to ARI in aortic rings pre-contracted with PE. In the presence of ARI, the contraction induced by KCl or PE was significantly (p < 0.05) decreased. Interestingly, the potassium channel blockade with 10 μM BaCl<sub>2</sub> (Kir), 10 μM glibenclamide (K<sub>ATP</sub>), 1 mM tetraethylammonium (TEA; KCa1.1), or 1 mM 4-aminopyridine (4-AP; Kv) significantly (<i>p</i> < 0.05) reduced the ARI-induced relaxation. ARI significantly (<i>p</i> < 0.05) reduced the contractile response to agonist of Ca<sub>V</sub>1.2 channels (Bay K8644; 10 nM), likely reducing the influx of extracellular calcium through plasma membrane. The mechanisms associated with this process suggest an activation of the potassium channels, a calcium-induced antagonism and endothelium independent vasodilation that possibly involves the nitric oxide-independent soluble guanylate cyclase pathway.
|
|---|
