Antihypertensive and vasorelaxant effects of ethanol extract of stem barks from Zanthoxylum rhoifolium Lam. in rats.
Administration of ethanol extract of stem bark from Z. rhoifolium (EEtOH-ZR) induced hypotension associated with a dual effect in heart rate in normotensive rats. This response was highlighted in spontaneously hypertensive rats (SHR). In rat superior mesenteric artery rings, the cumulative addition of EEtOH-ZR (0.1-750 microg/mL) on a phenylephrine-induced pre-contraction (10(-5) M) promoted a vasorelaxant effect by a concentration-dependent manner and independent of vascular endothelium. A similar effect was obtained on KCl-induced pre-contractions (80 mM). EEtOH-ZR attenuated contractions induced by cumulative addition of CaCl2 (10(-6)-3 x 10(-2) M) in depolarizing medium without Ca2+ only at 500 or 750 microg/mL. Likewise, on S-(-)-Bay K 8644-induced pre-contractions (10(-7) M), the EEtOH-ZR-induced vasorelaxant effect was attenuated. EEtOH-ZR (27, 81, 243 or 500 microg/mL) inhibited contractions induced by cumulative addition of phenylephrine (10(-9) - 10(-5) M) in endothelium-denuded preparations or by a single concentration (10(-5) M) in a Ca(2+)-free medium. The involvement of K+ channels was evaluated by tetraethylammonium (3 mM); the EEtOH-ZR-induced vasorelaxation was not attenuated. Thus, calcium influx blockade through voltage-operated calcium channels (CavL) and inhibition of calcium release from intracellular stores are probably underlying EEtOH-ZR-induced cardiovascular effects.
aMedicinal Plants Research Center, Federal University of Piauí, Av. Nossa Senhora de Fátima s/n, SG-15, 64049-550 Teresina, PI, Brazil.
Edson Santos
ES
Ferreira-Filho
Daniel Dias Rufino
DD
Arcanjo
Lucas Henrique Porfírio
LH
Moura
José Couras
JC
da Silva-Filho
Emanuel Tenório
ET
Paulino
Eurica Adélia Nogueira
EA
Ribeiro
Mariana Helena
MH
Chaves
Rita de Cássia Meneses
Rde C
Oliveira
Aldeídia Pereira
AP
de Oliveira
D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects; D002120:Calcium Channel Agonists / Q000494:pharmacology; D015220:Calcium Channels / Q000187:drug effects; D002122:Calcium Chloride / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000187:drug effects; D000431:Ethanol / Q000737:chemistry*; D008297:Male; D010656:Phenylephrine / Q000494:pharmacology; D024301:Plant Bark / Q000737:chemistry*; D018547:Plant Stems / Q000737:chemistry*; D015221:Potassium Channels / Q000187:drug effects; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D011918:Rats, Inbred SHR; D017208:Rats, Wistar; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014664:Vasodilation / Q000187:drug effects*; D014665:Vasodilator Agents / Q000494:pharmacology*; D032106:Zanthoxylum / Q000737:chemistry*
D000959:Antihypertensive Agents; D002120:Calcium Channel Agonists; D015220:Calcium Channels; D015221:Potassium Channels; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; D010656:Phenylephrine; D000431:Ethanol; D011189:Potassium Chloride; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D002122:Calcium Chloride