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Mar. Drugs 2011, 9(10), 2075-2088; doi:10.3390/md9102075

Vasorelaxation, Induced by Dictyota pulchella (Dictyotaceae), a Brown Alga, Is Mediated via Inhibition of Calcium Influx in Rats

* and
Biotechnology Center, Federal University of Paraiba, João Pessoa, PB 58.051-900, Brazil
* Author to whom correspondence should be addressed.
Received: 23 August 2011 / Revised: 13 October 2011 / Accepted: 17 October 2011 / Published: 24 October 2011
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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, CH2Cl2/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 A2 agonist U-46619 (100 nM). Furthermore, CME and HEP reversed CaCl2-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 Ca2+ 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 Ca2+ influx through blockade of voltage-operated calcium channels.
Keywords: calcium; hypotension; mesenteric artery; vasodilatation calcium; hypotension; mesenteric artery; vasodilatation
This is an open access article distributed under the Creative Commons Attribution License (CC BY) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Queiroz, T.M.; Machado, N.T.; Furtado, F.F.; Oliveira-Filho, A.A.; Alustau, M.C.; Figueiredo, C.S.; Miranda, G.E.C.; Barbosa-Filho, J.M.; Braga, V.A.; Medeiros, I.A. Vasorelaxation, Induced by Dictyota pulchella (Dictyotaceae), a Brown Alga, Is Mediated via Inhibition of Calcium Influx in Rats. Mar. Drugs 2011, 9, 2075-2088.

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