Cardiovascular Effects Induced by Linalool in Normotensive and Hypertensive Rats

Abstract

Linalool is a monoterpene alcohol and constituent of several Brazilian aromatic medicinal plants, popularly used against hypertension. Cardiovascular effects induced by linalool were evaluated. In normotensive rats, (±)-linalool [1, 5, 10, and 20 mg/kg body weight (BW); intravenous (i.v.)]-induced hypotension was associated with tachycardia, which was attenuated by atropine (2 mg/kg BW) and NG-nitro-L-arginine methyl ester (20 mg/kg BW), but was not modified after indomethacin (5 mg/kg BW) administration. In hypertensive rats, linalool [200 mg/kg BW; oral (v.o.)] reduced blood pressure without changing the heart rate. In intact rings of rat mesenteric artery precontracted with 10 μM phenylephrine, linalool (from 6.4 · 10 - 6 to 6.4 · 10 - 3 M) induced relaxations in a concentration-dependent manner [Emax = (115 ± 13)%] that were not changed after atropine administration [Emax = (105 ± 2)%], and were not different from those obtained in endothelium-denuded rings precontracted with phenylephrine [Emax = (108 ± 7)%] or 80 mM KCl [Emax = (113 ± 7)%] or tetraethylammonium incubation [Emax = (105 ± 12)%]. Linalool (1.9 · 10- 3 M) antagonized the contractions induced by CaCl2 (3 · 10 - 6 - 10 - 2 M) (maximal inhibition, 81%). Furthermore, linalool inhibited the contractions induced by 10 μM phenylephrine or 20 mM caffeine. In conclusion, these results demonstrate that linalool reduces blood pressure probably due to a direct effect on the vascular smooth muscle leading to vasodilation.