title: Vasorelaxation, induced by Dictyota pulchella (Dictyotaceae), a brown alga, is mediated via inhibition of calcium influx in rats.
abstract: This study aimed to investigate the cardiovascular effects elicited by Dictyota pulchella, a brown alga, using in vivo and in vitro approaches. In normotensive conscious rats, CH(2)Cl(2)/MeOH Extract (CME, 5, 10, 20 and 40 mg/kg) from Dictyota pulchella produced dose-dependent hypotension (-4 ± 1; -8 ± 2; -53 ± 8 and -63 ± 3 mmHg) and bradycardia (-8 ± 6; -17 ± 11; -257 ± 36 and -285 ± 27 b.p.m.). In addition, CME and Hexane/EtOAc Phase (HEP) (0.01-300 μg/mL) from Dictyota pulchella induced a concentration-dependent relaxation in phenylephrine (Phe, 1 μM)-pre-contracted mesenteric artery rings. The vasorelaxant effect was not modified by the removal of the vascular endothelium or pre-incubation with KCl (20 mM), tetraethylammonium (TEA, 3 mM) or tromboxane A(2) agonist U-46619 (100 nM). Furthermore, CME and HEP reversed CaCl(2)-induced vascular contractions. These results suggest that both CME and HEP act on the voltage-operated calcium channel in order to produce vasorelaxation. In addition, CME induced vasodilatation after the vessels have been pre-contracted with L-type Ca(2+) channel agonist (Bay K 8644, 200 nM). Taken together, our data show that CME induces hypotension and bradycardia in vivo and that both CME and HEP induce endothelium-independent vasodilatation in vitro that seems to involve the inhibition of the Ca(2+) influx through blockade of voltage-operated calcium channels.
authors.affiliation: Biotechnology Center, Federal University of Paraiba, João Pessoa, PB 58.051-900, Brazil.
authors.forename: Thyago M
authors.initials: TM
authors.lastname: Queiroz
authors.affiliation: Biotechnology Center, Federal University of Paraiba, João Pessoa, PB 58.051-900, Brazil.
authors.forename: Natália T
authors.initials: NT
authors.lastname: Machado
authors.affiliation: Biotechnology Center, Federal University of Paraiba, João Pessoa, PB 58.051-900, Brazil.
authors.forename: Fabíola F
authors.initials: FF
authors.lastname: Furtado
authors.affiliation: Biotechnology Center, Federal University of Paraiba, João Pessoa, PB 58.051-900, Brazil.
authors.forename: Abrahão A
authors.initials: AA
authors.lastname: Oliveira-Filho
authors.affiliation: Biotechnology Center, Federal University of Paraiba, João Pessoa, PB 58.051-900, Brazil.
authors.forename: Maria C
authors.initials: MC
authors.lastname: Alustau
authors.affiliation: Biotechnology Center, Federal University of Paraiba, João Pessoa, PB 58.051-900, Brazil.
authors.forename: Camila S
authors.initials: CS
authors.lastname: Figueiredo
authors.affiliation: Biotechnology Center, Federal University of Paraiba, João Pessoa, PB 58.051-900, Brazil.
authors.forename: George E C
authors.initials: GEC
authors.lastname: Miranda
authors.affiliation: Biotechnology Center, Federal University of Paraiba, João Pessoa, PB 58.051-900, Brazil.
authors.forename: José M
authors.initials: JM
authors.lastname: Barbosa-Filho
authors.affiliation: Biotechnology Center, Federal University of Paraiba, João Pessoa, PB 58.051-900, Brazil.
authors.forename: Valdir A
authors.initials: VA
authors.lastname: Braga
authors.affiliation: Biotechnology Center, Federal University of Paraiba, João Pessoa, PB 58.051-900, Brazil.
authors.forename: Isac A
authors.initials: IA
authors.lastname: Medeiros
mesh_terms: D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid / Q000494:pharmacology; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D000818:Animals; D001688:Biological Products / Q000494:pharmacology; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D015220:Calcium Channels / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000187:drug effects; D000459:Phaeophyceae / Q000737:chemistry*; D010656:Phenylephrine / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D019789:Tetraethylammonium / Q000494:pharmacology; D014664:Vasodilation / Q000187:drug effects*; D014665:Vasodilator Agents / Q000494:pharmacology*
chemical_list: D001688:Biological Products; D002121:Calcium Channel Blockers; D015220:Calcium 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; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid
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