Cardiovascular effects of Urtica dioica L. in isolated rat heart and aorta.
Urtica dioica L. or Nettle (Urticaceae) is widely used in oriental Morocco to treat hypertension. Aqueous extract of Nettle (AEN) also exerts a hypotensive action in the rat in vivo. The aim of this work was to characterize the specific cardiac and vascular effects of AEN. In the isolated Langendorff perfused rat heart, AEN (1 and 2 g/l) markedly decreased heart rate and increased left ventricular pressure. Higher concentration (5 g/l) even led to cardiac arrest. Although carbachol mimicked the bradycardiac effect of AEN, atropine (a muscarinic receptor antagonist, 1 micro M) did not modify the response. Beside its action on myocardium, AEN also affected vascular contractility. Indeed, AEN (0.1-5 g/l) produced a dose-dependent increase in basal tone of isolated rat aorta. This effect was endothelium independent and was abolished by 1 micro M prazosin (an alpha1-adrenergic antagonist). AEN had little additional effects when the aorta was precontracted by noradrenaline (1 micro M) or KCl (40 mM). Our data indicate that AEN produces a vasoconstriction of the aorta which is due to activation of alpha1-adrenergic receptors. However, AEN also induces a strong bradycardia through non-cholinergic and non-adrenergic pathways which might compensate for its vascular effect and account for the hypotensive action of Urtica dioica L described in vivo.
Legssyer
Abdelkhaleq
A
Laboratoire de Physiologie et Pharmacologie Cellulaire, Département de Biologie, Facultédes Sciences, Université Mohamed Premier, BP 524, 60000 Oujda, Maroc. alegssyer@sciences.univ-oujda.ac.ma
Ziyyat
Abderrahim
A
Mekhfi
Hassane
H
Bnouham
Mohamed
M
Tahri
Abdelhafid
A
Serhrouchni
Mohamed
M
Hoerter
Jacqueline
J
Fischmeister
Rodolphe
R
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects* / Q000502:physiology; D001285:Atropine / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects; D002217:Carbachol / Q000494:pharmacology; D004347:Drug Interactions; D006339:Heart Rate / Q000187:drug effects*; D066298:In Vitro Techniques; D008297:Male; D018727:Muscarinic Antagonists / Q000494:pharmacology; D009638:Norepinephrine / Q000494:pharmacology; D010936:Plant Extracts / Q000494:pharmacology*; D011224:Prazosin / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D026982:Urtica dioica; D014661:Vasoconstriction / Q000187:drug effects
D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D018727:Muscarinic Antagonists; D010936:Plant Extracts; D001285:Atropine; D002217:Carbachol; D009638:Norepinephrine; D011224:Prazosin