Abstract
The aim of this work was to characterize the vasorelaxant effect produced by Sida santaremnensis ethanol extract (Ssan-EtOH) in rat superior mesenteric artery. Ssan-EtOH showed neither acute toxicity nor hemolytic activity. In the other hand, it induced a concentration-dependent vasorelaxant effect on phenylephrine (10 μmol/L) or KCl (80 mmol/L)-induced pre-contractions in endothelium-intact rat mesenteric artery rings, which attenuated after endothelium removal, without changes in maximum effect. NG-nitro-L-arginine methyl ester (L-NAME) (100 μmol/L), indomethacin (10 µmol/L), atropine (1 nmol/L), KCl (20 mmol/L) or tetraethylammonium (3 mmol/L) pretreatment also induced a response attenuation. The endothelium-derived hyperpolarizing factor (EDHF) involvement in Ssan-EtOH-induced vasorelaxant response was verified after L-NAME (100 μmol/L) plus Indomethacin (10 μmol/L) plus tetraethylammonium (3 mmol/L) pretreatment and this vasorelaxation was decreased. In endothelium-denuded rings, Ssan-EtOH was able to inhibit phenylephrine-induced contractions (10-9 to 10-5 mol/L) in a concentration-dependent manner. In a nominally without Ca2+ depolarizing Tyrode solution, Ssan-EtOH inhibited CaCl2 (10-6 – 3 x 10-2 mol/L)-induced contractions in a concentration-dependent manner. The endothelium-dependent Ssan-EtOH-induced vasorelaxant effect probably involves the participation of the nitric oxide synthase (NOS) and cyclooxygenases (COX) pathways, as well muscarinic receptors and EDHF and the endothelium-independent effect probably occurs by Ca2+ influx inhibition through voltage-operated calcium channels. Key words: Sida santaremnensis, superior mesenteric artery, Malvaceae, vasorelaxation.
Highlights
IntroductionMonteiro (Malvaceae) is popularly known as “guanxuma” and occurs in the Americas, Africa and Asia
The aim of this work was to characterize the vasorelaxant effect produced by Sida santaremnensis ethanol extract (Ssan-EtOH) in rat superior mesenteric artery
The endothelium-dependent Ssan-EtOH-induced vasorelaxant effect probably involves the participation of the nitric oxide synthase (NOS) and cyclooxygenases (COX) pathways, as well muscarinic receptors and endothelium-derived hyperpolarizing factor (EDHF) and the endothelium-independent effect probably occurs by Ca2+ influx inhibition through voltage-operated calcium channels
Summary
Monteiro (Malvaceae) is popularly known as “guanxuma” and occurs in the Americas, Africa and Asia. Species from the Sida genus have been used by traditional medicine to treat cough, fever (Hansen et al, 1995; Bork et al, 1997), vascular disorders and hypertension (Noumi et al, 1999). Other studies have shown that the Sida cordifolia induces hypotension and bradycardia in normotensive rats probably by decreasing the vascular resistance mediated by endothelium-derived relaxing factors (EDRFs) (Santos et al, 2006). The smooth muscle is the main kind of muscle that
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