In vitro vascular smooth muscle contractile activity of Aspilia africana extract on rat aortic preparations.
Aspilia africana is widely used in ethnomedical practice in Africa for its ability to stop bleeding, even from a severed artery, as well as promote rapid healing of wounds and sores, and for the management of problems related to cardiovascular diseases. In the present paper, the methylene chloride/methanol extract of A. africana leaves was tested for its contractile activity in vitro. Rings of rat aorta, with or without an intact endothelium, were mounted in tissue baths, contracted with norepinephrine, and then exposed to the plant extract. The effect of the extract was also assessed on the baseline tension of aortic rings in normal and calcium-free PSS. At the lower doses, A. africana slowly re-inforced contractions induced by norepinephrine and relaxed precontracted tension at the highest concentration. The relaxant activity of the extract was endothelium-independent and was not modified by pre-treatment with Nw-nitro-L-arginine methyl ester or indomethacin, suggesting that its effect was not mediated by either nitric oxide or prostacyclin. A. africana extract induced slow and progressive increase in the basal vascular tone which was partially endothelium-dependent. In calcium-free PSS, a high proportion of the contractile activity was inhibited (77%), suggesting that A. africana contractile activity in vascular tissue depends, in part, on extracellular calcium.
Dimo
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T
Animal Physiology Laboratory, Department of Animal Biology & Physiology, Faculty of Science, P.O. Box 812, University of Yaounde I, Cameroon.
Tan
P V
PV
Dongo
E
E
Kamtchouing
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P
Rakotonirina
S V
SV
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects; D019659:Asteraceae / Q000737:chemistry*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009126:Muscle Relaxation / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D010936:Plant Extracts / Q000494:pharmacology; D010946:Plants, Medicinal / Q000737:chemistry*; D051381:Rats; D017207:Rats, Sprague-Dawley
D004791:Enzyme Inhibitors; D010936:Plant Extracts; D000109:Acetylcholine; D019331:NG-Nitroarginine Methyl Ester