New Insights on Relaxant Effects of (—)‐borneol Monoterpene in Rat Aortic Rings

The monoterpene alcohol (−)‐borneol has many biological effects such as sedative, anti‐inflammatory, analgesic, anti‐nociceptive, antithrombotic and vasorelaxant effects. Our objective in this study was to investigate the mechanism of action of (−)‐borneol and determine its vasorelaxant effect. (−)‐Borneol was tested on isolated aortic rings contracted with PE (10 −6 m ). This study was performed in the absence or in the presence of endothelium, L‐ NAME (100 μ m ), indomethacin (10 μ m ), TEA (1 and 10 m m ), 4‐ AP (1 m m ) or glibenclamide (1 m m ) to assess the participation of EDRF , nitric oxide, prostanoids and potassium channels on the relaxing effect of (−)‐borneol. In this work, (−)‐borneol induced a relaxant effect in aortic rings, with and without endothelium, in a concentration‐dependent manner. The pharmacological characterization obtained using L‐ NAME , indomethacin, TEA , 4‐ AP and glibenclamide demonstrates that the effect of (−)‐borneol was modified in the presence of L‐ NAME , indomethacin and glibenclamide showing that these signal transduction pathways are involved in the relaxing effect of the monoterpene. (−)‐Borneol has a vasorelaxant effect that depends on the presence of vascular endothelium, with the participation of nitric oxide and prostanoids. Also, (−)‐borneol displayed a direct action on the vascular smooth muscle, greatly dependent on K ATP channels.