The Protective Effect of Indole Alkaloid Vincanine Against Hypoxia-Induced Vasorelaxation Model of Rat Aorta

Abstract

Introduction: Using conventional organ bath procedures, the current study sought to determine how vincanine hydrochloride affected vasorelaxation brought on by hypoxia in rat aortic rings. Methods: To induce hypoxia, we used a glucose-free Krebs solution that was infused with 95% N2 and 5% CO2. After 60 minutes of hypoxia, the effect of vincanine was evaluated on aortic rings that were precontracted with either 50 mM KCl or 1 µM phenylephrine (PE). The effect of vincanine was more noticeable in aortic rings that had been precontracted by PE as opposed to KCl. Additionally, when verapamil, a blocker of L-type VDCCs, was preincubated with endothelium-intact aortic rings and KCI was used for precontraction, the effect of vincanine on hypoxia-induced vasorelaxation was significantly reduced. Results: Vincanine inhibited hypoxia-induced vasorelaxation in aortic rings precontracted with PE in a calcium-free buffer. Furthermore, the presence of glibenclamide, a specific inhibitor of ATP-sensitive K+-channels (KATP), and tetraethylammonium chloride (TEA), a nonspecific inhibitor of calcium-activated large conductance K+-channels (BKca), significantly reduced the effect of vincanine on hypoxia-induced vasorelaxation. The removal of the endothelium also had a significant impact on the effect of vincanine on hypoxia-induced vasorelaxation. Conclusion: The present findings showed that alkaloid vincanine isolated from the leaves of Vinca minor H. significantly abolished the hypoxia-induced vasorelaxation in rat aorta. The obtained results suggest that vincanine may protect the rat aorta against hypoxic injuries in the vasculature.