In non-anesthetized normotensive rats, Hyptis fruticosa essential oil (HFEO, 5, 10, 20 and 40 mg/kg; i.v.) induced hypotension associated with tachycardia. In intact and isolated rings of rat superior mesenteric artery (control), HFEO (1 – 1000 μ g/ml, n =6, cumulatively) induced concentration-dependent relaxations of tonus induced by 10 μ M phenylephrine (Phe) (pD 2 =2.6±0.27; E max =64±8.3%). In denuded endot...