Antihypertensive effects of crude extracts from leaves of Echinodorus grandiflorus.
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.
Lessa
Marcos Adriano
MA
Laboratório de Farmacologia Neuro-Cardiovascular, Instituto Oswaldo Cruz, FIOCRUZ, Rio de Janeiro, Brazil.
Araújo
Cláudia Valéria
CV
Kaplan
Maria Auxiliadora
MA
Pimenta
Daniel
D
Figueiredo
Maria Raquel
MR
Tibiriçá
Eduardo
E
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D034901:Alismataceae; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000494:pharmacology; D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology*; D001262:Atenolol / Q000494:pharmacology; D001381:Azepines / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects; D001920:Bradykinin / Q000031:analogs & derivatives / Q000494:pharmacology; D001938:Brazil; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D004656:Enalapril / Q000494:pharmacology; D006439:Hemodynamics / Q000187:drug effects*; D007213:Indomethacin / Q000494:pharmacology; D008297:Male; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism; D008517:Phytotherapy; D010936:Plant Extracts / Q000494:pharmacology; D018515:Plant Leaves; D010980:Platelet Membrane Glycoproteins / Q000037:antagonists & inhibitors; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D043562:Receptors, G-Protein-Coupled / Q000037:antagonists & inhibitors; D014230:Triazoles / Q000494:pharmacology
D000319:Adrenergic beta-Antagonists; D000806:Angiotensin-Converting Enzyme Inhibitors; D000959:Antihypertensive Agents; D001381:Azepines; D016861:Cyclooxygenase Inhibitors; D010936:Plant Extracts; D010980:Platelet Membrane Glycoproteins; D043562:Receptors, G-Protein-Coupled; D014230:Triazoles; C039351:platelet activating factor receptor; C052518:WEB 2086; D009569:Nitric Oxide; D001262:Atenolol; D004656:Enalapril; C065679:icatibant; D001920:Bradykinin; D019331:NG-Nitroarginine Methyl Ester; D007213:Indomethacin