title: Investigation of mechanisms involved in (-)-borneol-induced vasorelaxant response on rat thoracic aorta.
abstract: The monoterpene (-)-borneol is present in essential oils of several medicinal plants. The aim of this study was to evaluate (-)-borneol effects on rat thoracic aorta artery rings. The cumulative addition of (-)-borneol (10(-9) -3 × 10(-4)  M) on a phenylephrine-induced pre-contraction (10(-6)  M) promoted a vasorelaxant effect in a concentration-dependent manner and independent of vascular endothelium. A similar effect was obtained on KCl-induced pre-contractions (80 mM). (-)-Borneol (10(-5) -3 × 10(-4 ) M) inhibited contractions induced by cumulative addition of CaCl2 (10(-6) -3 × 10(-2)  M) in depolarizing medium without Ca(2+) in a concentration-dependent manner. On S-(-) Bay K 8644-induced pre-contractions (10(-7)  M), (-)-borneol did not induce significant changes compared with KCl-induced pre-contractions. In a Ca(2+) -free medium, (-)-borneol (10(-5) , 10(-4) or 10(-3)  M) interfered in calcium mobilization from phenylephrine (10(-6)  M)- or caffeine (20 mM)-sensitive intracellular stores. The involvement of K(+) channels was evaluated by tetraethylammonium (3 mM), 4-aminopyridine (1 mM) and glibenclamide (10(-5)  M) pre-treatment, and (-)-borneol-induced vasorelaxation was markedly attenuated. Thus, this vasorelaxant effect can probably be attributed to calcium influx blockade through voltage-operated calcium channels (CaV L), calcium mobilization from intracellular stores and potassium channels activation.
authors: Medicinal Plants Research Center, Federal University of Piauí, BrazilDepartament of Physiology, Federal University of Sergipe, Brazil.
authors: José Couras
authors: JC
authors: Silva-Filho
authors: Nelma Neylanne P M
authors: NN
authors: Oliveira
authors: Daniel D R
authors: DD
authors: Arcanjo
authors: Lucindo J
authors: LJ
authors: Quintans-Júnior
authors: Sócrates C H
authors: SC
authors: Cavalcanti
authors: Márcio Roberto V
authors: MR
authors: Santos
authors: Rita de Cássia M
authors: Rde C
authors: Oliveira
authors: Aldeídia P
authors: AP
authors: Oliveira
mesh_terms: D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000009:adverse effects; D015761:4-Aminopyridine / Q000494:pharmacology; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects*; D002122:Calcium Chloride / Q000009:adverse effects; D001892:Camphanes / Q000494:pharmacology*; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism; D005905:Glyburide / Q000494:pharmacology; D010656:Phenylephrine / Q000009:adverse effects; D015221:Potassium Channels / Q000187:drug effects; D011189:Potassium Chloride / Q000009:adverse effects; D051381:Rats; D019789:Tetraethylammonium / Q000494:pharmacology; D014665:Vasodilator Agents / Q000494:pharmacology*
chemical_list: D001892:Camphanes; D015221:Potassium Channels; D014665:Vasodilator Agents; D010656:Phenylephrine; D019789:Tetraethylammonium; D011189:Potassium Chloride; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D015761:4-Aminopyridine; C022871:isoborneol; D002122:Calcium Chloride; D005905:Glyburide