Curcuma Longa Abolishes Phenylephrine-Induced Contractions in Isolated Aortic Artery of Rats

Abstract Background: Curcuma longa has biological effects. Its cardiovascular activities are yet to be scientifically studied. Objectives: To investigate the vasorelaxant effects of the aqueous extract of Curcuma longa (AECL). Methods: Aortic annuli of normotensive rats, with or without endothelium, were set up in a data storage system with nutrient solution in recipients, with scientifically recommended temperature, aeration and tension. Over contraction by Phenylephrine, the AECL (1, 3, 10, 30, 100, 300 and 1000 µg/mL) was incubated before and after incubation with atropine or L-name or indomethacin. An AECL concentration-response curve was also built over contractions caused by elevation of extracellular K+. Data were significant when p < 0.05, with GraphPad Prism 6.0 software resolutions. Results: The AECL induced 100% vasorelaxation also in the endothelium-free annuli. The part of the endothelium-dependent effect had EC50 = 4.32 ± 0.05 µg/mL. With inhibition of NO production, the EC50 increased to 126.50 ± 2.35 µg/mL; after inhibition of prostacyclin production, to 124.6 ± 0.05 µg/mL; and after muscarinic blockade, to 437.10 ± 0.2 µg/mL. Opening of K+ channels (relaxation of 56.98%) and VOCC blockade (relaxation of 31.56%) were evident. Conclusion: AECL induced significant vasorelaxation, being more significant in the presence of endothelium. The muscarinic pathway seems to be the main one involved in this effect, followed by the NO production and prostacyclin pathways. The activity in K+ channels by AECL was more significant than its VOCC blockade. The use of other models and tools to study action mechanisms will be important and elucidating.