Cardiovascular effects of Urtica dioica L. (Urticaceae) roots extracts: in vitro and in vivo pharmacological studies.
Urtica dioica (Urticaceae) is a plant principally used in the traditional medicine of oriental Marocco as antihypertensive remedy (J. Ethnopharmacol., 58 (1997), 45). The aim of this work was to evaluate a possible direct cardiovascular action of the plant and to investigate its mechanism of action. In aortic preparations with intact and functional endothelial layer, pre-contracted with KCl 20 mM or norepinephrine 3 microM, the crude aqueous and methanolic extracts of the plant roots, as well as purified fractions elicited a vasodilator action. Nevertheless, the vasodilator activity was not present in aortic rings without endothelial layer. In aortic rings with intact endothelial layer, the vasorelaxing effect was abolished by L-NAME, a NO-biosynthesis inhibitor, and ODQ, a guanylate cyclase inhibitor. Furthermore, potassium channel blockers (TEA, 4-aminopyridine, quinine, but not glybenclamide) antagonized the vasodilator action of the purified fraction F1W of U. dioica. The same fraction produced a marked decrease of inotropic activity, in spontaneously beating atria of guinea-pig, and a marked, but transient, hypotensive activity on the blood pressure of anaesthetized rats. It is concluded that U. dioica can produce hypotensive responses, through a vasorelaxing effect mediated by the release of endothelial nitric oxide and the opening of potassium channels, and through a negative inotropic action.
Testai
Lara
L
Dipartimento di Psichiatria, Neurobiologia, Farmacologia e Biotecnologie, Università di Pisa, via Bonanno 6, 56126 Pisa, Italy.
Chericoni
Silvio
S
Calderone
Vincenzo
V
Nencioni
Giulia
G
Nieri
Paola
P
Morelli
Ivano
I
Martinotti
Enrica
E
D000818:Animals; D001011:Aorta / Q000187:drug effects / Q000502:physiology; D001794:Blood Pressure / Q000187:drug effects; D002317:Cardiovascular Agents / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D002319:Cardiovascular System / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000187:drug effects / Q000502:physiology; D006168:Guinea Pigs; D016015:Logistic Models; D008297:Male; D010936:Plant Extracts / Q000494:pharmacology*; D018517:Plant Roots / Q000737:chemistry*; D051381:Rats; D017208:Rats, Wistar; D026982:Urtica dioica / Q000737:chemistry*; D014664:Vasodilation / Q000187:drug effects
D002317:Cardiovascular Agents; D010936:Plant Extracts