Antihypertensive effects of crude extracts from leaves of Echinodorus grandiflorus

Abstract

The antihypertensive action of a crude ethanolic extract (EEEG) from leaves of Echinodorus grandiflorus (Alismataceae) was investigated in spontaneously hypertensive rats. The intraperitoneal injection of increasing doses of EEEG (300-1000 mg/kg) elicited dose-dependent reductions in mean arterial pressure (MAP) that were paralleled by reductions of cardiac output and systemic vascular resistance, reaching the maximum of 23 +/- 5%, 13 +/- 3% and 18 +/- 4%, respectively (n = 5, P < 0.05). Comparable reductions of MAP were obtained upon i.v. administration of EEEG (3-100 mg/kg), reaching the maximum decrease of 51 +/- 6% (n = 7; P < 0.001). The blockade of nitric oxide synthesis significantly reduced the hypotension induced by i.v. administration of EEEG. Moreover, the pre-treatment of the animals with a selective antagonist of cholinergic muscarinic receptors or of platelet-activating factor (PAF) receptors partially blunted the cardiovascular effects of EEEG. The i.v. pre-treatment with the selective B(2) bradykinin receptor antagonist HOE 140 or with indomethacin, an inhibitor of the enzyme cyclooxygenase, did not prevent the hypotensive effects induced by EEEG. Finally, the chronic oral treatment with EEEG presented a significant antihypertensive effect that was comparable to that of reference antihypertensive drugs currently used to treat arterial hypertension. It is concluded that EEEG elicits significant acute antihypertensive effects through the release of nitric oxide and the stimulation of cholinergic muscarinic and PAF receptors. Moreover, our results suggest that EEEG may be appropriate to chronic oral treatment of arterial hypertension.

In vitro antioxidant capacity of tea of Echinodorus grandiforus, “leather hat,” in Wistar rat liver

“…Brugiolo et al (2011) showed that the extract of E. grandiflorus was able to modulate allergic pulmonary inflammation, and it may also be useful as a potential therapeutic agent for asthma (Lessa et al 2008).…”

Effect of Tulbaghia violacea on the blood pressure and heart rate in male spontaneously hypertensive Wistar rats

“…The prominent BP profile and magnitude was that of atropine ( figure 4.44 a). Infusion of agonists was done 20 minutes after infusing atropine in most studies in which atropine was used to block the muscarinic receptors (Muntzel et al, 1997;Dimo et al, 2003;Delphine Holopherne et al, 2008;Khwanchuea et al, 2008;Lessa et al, 2008;Liu et al, 2008;Rattmann et al, 2008;Shirasaka et al, 2009;De Menezes et al, 2010). violacea were significantly (p < 0.05) higher than those observed with muscarine after pretreatment of animals with atropine.…”

“…The bradykinin system regulates sodium water balance, renal and cardiac haemodynamics, and BP by mediating and modulating a) the vasoconstricting RAAS; and b) the vasodilating prostaglandin, prostacyclin, adrenomedullin and NO. Reduced activity of the system has been reported in various hypertensive situations in both clinical and experimental models of HTN (Lessa et al, 2008;De Leo et al, 2009;Günthner et al, 2009;Sharma, 2009;Bakris, 2010;Hanif et al, 2010).…”

“…Muscarine (2.5 µg/kg) was then infused into the same animal, after the BP and HR returned to the level prior to the infusion of the MLE. The drugs were infused 20 minutes after atropine infusion (Thán et al, 2000;Dimo et al, 2003;Dabire, 2004;Adami et al, 2006;Ajay et al, 2007; D. Holopherne et al, 2008;Khwanchuea et al, 2008;Lessa et al, 2008;Rattmann et al, 2008;De Menezes et al, 2010).…”

Possible mechanisms of action of the hypotensive effect ofAnnona muricata(soursop) in normotensive Sprague–Dawley rats

“…The effect of the aqueous leaf extract was examined after administration of the muscarinic receptor antagonist, atropine (2 mg/kg), the beta-adrenoceptor antagonist, propranolol (1 mg/kg), the histamine H 1 receptor agonist, mepyramine (5 mg/kg), or the nitric oxide synthase inhibitor, N ω -nitro-l-arginine methyl ester (l-NAME, 5 mg/kg) (Weldon et al, 1995;de Moura et al, 2005;Ghayur et al, 2005;Lessa et al, 2008;Diaz-Juarez et al, 2009). Each drug was given intravenously and allowed to incubate for 5 min before a bolus injection of 19.41 mg/kg (ED 50 ) A. muricata extract was infused.…”