Vasorelaxant effect of Valeriana edulis ssp. procera (Valerianaceae) and its mode of action as calcium channel blocker.
OBJECTIVE
The aim was to evaluate the relaxant effect of extracts from Valeriana edulis and determine the possible mechanism of action of the hexanic extract as vasorelaxant agent.


METHODS
Extracts from rhizomes obtained by maceration (hexanic (HEVe), dichloromethanic (DEVe), methanolic (MEVe) and hydroalcoholic (HAEVe) (3.03-500 microg/ml)) were evaluated on aortic rat rings with and without endothelium.


RESULTS
Extracts induced a significant concentration-dependent and endothelium-independent relaxation on isolated rat aorta pre-contracted with noradrenaline (0.1 microM). HEVe, the most potent extract (0.15-50 microg/ml), induced relaxation in aortic rings pre-contracted with KCl (80 mM), with an IC50 value of 34.61 +/- 1.41 microg/ml and E(max) value of 85.0 +/- 4.38%. Pretreatment with HEVe (30 microg/ml) also inhibited contractile responses to noradrenaline and CaCl(2). HEVe (9.98 +/- 2.0 microg/ml) reduced noradrenaline-induced transient contraction in Ca(2+)-free solution, and inhibited contraction induced by KCl (80 mM). In endothelium-denuded rings, the vasorelaxant effect of HEVe was not modified by 1-H-[1,2,4]-oxadiazolo-[4,3a]-quinoxalin-1-one (1 microM), tetraethylammonium (5 mM), glibenclamide (10 microM) or 2-aminopyridine (100 microM).


CONCLUSIONS
Our results suggest that HEVe induces relaxation through an endothelium-independent pathway, involving blockade of Ca(2+) channels, and this effect could be related to the presence of valepotriates.
Estrada-Soto
Samuel
S
Facultad de Farmacia, Universidad Autónoma del Estado de Morelos, Avenida Universidad 1001, Col. Chamilpa, 62209, Cuernavaca, Morelos, México. enoch@uaem.mx
Rivera-Leyva
Julio
J
Ramírez-Espinosa
Juan José
JJ
Castillo-España
Patricia
P
Aguirre-Crespo
Francisco
F
Hernández-Abreu
Oswaldo
O
D000818:Animals; D001011:Aorta / Q000187:drug effects; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D002122:Calcium Chloride; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular; D020128:Inhibitory Concentration 50; D008297:Male; D009638:Norepinephrine; D010936:Plant Extracts / Q000494:pharmacology*; D011189:Potassium Chloride; D051381:Rats; D017208:Rats, Wistar; D027343:Rhizome; D014632:Valerian; D014661:Vasoconstriction / Q000187:drug effects*; D014665:Vasodilator Agents / Q000494:pharmacology*
D002121:Calcium Channel Blockers; D010936:Plant Extracts; D014665:Vasodilator Agents; D011189:Potassium Chloride; D002122:Calcium Chloride; D009638:Norepinephrine