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, 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.

α-Lipoic Acid Reduces Hypertension and Increases Baroreflex Sensitivity in Renovascular Hypertensive Rats

“…Hypertension and cardiovascular diseases are the leading cause of death in developed and developing countries [ 16 ], causing a great impact on global human health. In an attempt to reduce this impact, in recent decades several research groups have worked extensively to improve the treatment of cardiovascular diseases including the discovery of new therapy strategies and drugs [ 17 , 18 ]. Among these, we can highlight the use of an antioxidant therapy such as ROS scavengers and vitamins, superoxide dismutase (SOD) mimetics or NADPH oxidase inhibitors such as apocynin, to attenuate or prevents the development of hypertension [ 19 , 20 , 21 , 22 ].…”

Angiotensin-II-derived reactive oxygen species on baroreflex sensitivity during hypertension: new perspectives

“…In recent decades, several research groups have worked extensively to improve the treatment of hypertension and its complication, including reduction in BRS, focusing on the discovery of new therapy strategies and drugs (Lefkowits and Willerson, 2001; Queiroz et al, 2011). Among these, we can highlight the use of antioxidant therapy, such as ROS scavengers and vitamins, SOD mimetics or NAD(P)H oxidase inhibitors that has experimentally shown to attenuate or prevent the development of hypertension (Chen et al, 2001; Landmesser et al, 2003; Costa et al, 2009; Queiroz et al, 2012).…”

Marine Natural Products from Seaweeds

“…Como nas algas verdes, há vários artigos de atividades biológicas de extratos de algas pardas. [56][57][58] Sem dúvida, os produtos naturais de algas pardas marinhas têm um grande potencial para diversas atividades biológicas, sendo o grupo de macroalga mais estudado no Brasil em relação à química de produtos naturais. …”