Vasorelaxant effects of Brillantaisia nitens Lindau (Acanthaceae) extracts on isolated rat vascular smooth muscle

Brillantaisia nitens Lindau (Acanthaceae) is traditionally used in Cameroon for the treatment of many diseases including cardiovascular disorders. We have studied its vasorelaxant effects in rat vascular smooth muscle. In this study, aqueous, methylene chloride, methanol, and methylene chloride/meth...

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Bibliographic Details
Published in:Journal of ethnopharmacology 2007-04, Vol.111 (1), p.104-109
Main Authors: Dimo, T., Mtopi, O.-S. Bopda, Nguelefack, T.B., Kamtchouing, P., Zapfack, L., Asongalem, E.A., Dongo, E.
Format: Article
Language:English
Subjects:
Acanthaceae
Adenosine Triphosphate - metabolism
Animals
aorta
Aorta, Thoracic - drug effects
Aortic strips
bioassays
Biological and medical sciences
Brillantaisia nitens
Calcium - metabolism
Cameroon
chemical constituents of plants
Dose-Response Relationship, Drug
ethnobotany
General pharmacology
Glyburide - pharmacology
herbal medicines
In Vitro Techniques
Ion Channel Gating
leaves
Medical sciences
medicinal plants
medicinal properties
Methanol - chemistry
Methylene Chloride - chemistry
Methylene chloride/methanol extract
muscle relaxants
Muscle, Smooth, Vascular - drug effects
Muscle, Smooth, Vascular - metabolism
Pharmacognosy. Homeopathy. Health food
Pharmacology. Drug treatments
plant extracts
Plant Extracts - pharmacology
Plant Leaves
Potassium Channel Blockers - pharmacology
Potassium Channels - drug effects
Potassium Channels - metabolism
Rat
Rats
Rats, Wistar
smooth muscle
Solvents - chemistry
Tetraethylammonium - pharmacology
traditional medicine
Vasodilation - drug effects
Vasodilator Agents - chemistry
Vasodilator Agents - pharmacology
Vasorelaxation
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Summary:Brillantaisia nitens Lindau (Acanthaceae) is traditionally used in Cameroon for the treatment of many diseases including cardiovascular disorders. We have studied its vasorelaxant effects in rat vascular smooth muscle. In this study, aqueous, methylene chloride, methanol, and methylene chloride/methanol leaves extracts of Brillantaisia nitens were tested for their relaxing ability in vitro. Strips of rat aorta, with or without intact endothelium, were mounted in tissue baths, contracted with KCl (60 mM) or norepinephrine (10 −4 M), and then exposed to the plant extracts. These extracts exhibited concentration-dependent vasorelaxations of norepinephrine-induced contractions of intact aortic strips. The EC 50 were 0.42 ± 0.01 mg/ml (aqueous extract), 0.63 ± 0.02 mg/ml (methylene chloride extract), 0.73 ± 0.02 mg/ml (methanol extract) and 0.36 ± 0.02 mg/ml (methylene chloride/methanol extract). The methylene chloride/methanol (CH 2Cl 2/CH 3OH) extract was the most potent relaxing extract. It caused a concentration-dependent and endothelium-independent relaxation of the rat aortic strips contracted by KCl or norepinephrine. On the NE-induced contraction, its maximal relaxant activity (109%) due to the dose of 1.5 mg/ml, was not significantly modified by the pretreatment of aortic strips with indomethacin (89%, P > 0.05) or with l-NAME (103%, P > 0.05). This suggests that the vasorelaxation elicited by CH 2Cl 2/CH 3OH extract was not mediated via endothelium-derived prostacyclin or nitric oxide. In contrast, this relaxation was markedly reduced by tetraethylammonium, a blocker of non-selective K + channels and glibenclamide, a blocker of ATP-sensitive K + channels . The CH 2Cl 2/CH 3OH extract significantly inhibited Ca 2+-induced concentration-contraction and the Ca 2+ influx in aortic strips incubated with 60 mM KCl. These results indicate that the vasorelaxant effect of the CH 2Cl 2/CH 3OH extract of Brillantaisia nitens is due to an inhibition of Ca 2+ influx, possibly via the activation of ATP-sensitive K + channels.
ISSN:0378-8741
1872-7573
DOI:10.1016/j.jep.2006.10.035