Endothelium-dependent effects of the ethanolic extract of the mistletoe Psittacanthus calyculatus on the vasomotor responses of rat aortic rings

• Published in: Journal of ethnopharmacology Vol. 86; no. 2; pp. 213 - 218
• Main Authors: Rodrı́guez-Cruz, M.E, Pérez-Ordaz, L, Serrato-Barajas, B.E, Juárez-Oropeza, M.A, Mascher, D, Paredes-Carbajal, M.C
• Format: Journal Article
• Language: English
• Published: Shannon Elsevier Ireland Ltd 01.06.2003; Elsevier
• Subjects: Animals; Biological and medical sciences; Dose-Response Relationship, Drug; Drug Interactions; Endothelium; Endothelium, Vascular - drug effects; Flavonoids; General pharmacology; Male; Medical sciences; Medicine, Traditional; Mexico; Mistletoe; Muscle, Smooth, Vascular - drug effects; NG-Nitroarginine Methyl Ester - pharmacology; Nitric oxide; Pharmacognosy. Homeopathy. Health food; Pharmacology. Drug treatments; Phenylephrine - pharmacology; Plant Leaves; Plant Preparations - isolation & purification; Plant Preparations - pharmacology; Plant Proteins; Psittacanthus calyculatus; Rats; Rats, Wistar; Ribosome Inactivating Proteins, Type 2; Toxins, Biological - isolation & purification; Toxins, Biological - pharmacology; Vasoconstriction - drug effects; Vasoconstrictor Agents - pharmacology; Vasodilation - drug effects; Central America; Mexico; America; Flavonoids; Mistletoe; Nitric oxide; Psittacanthus calyculatus; Endothelium; Rat; Cardiovascular disease; Extract; Flavonoid; Loranthaceae; Medicinal plant; Folk medicine; Dicotyledones; Angiospermae; Aorta; Hypertension; Rodentia; In vitro; Biological activity; Vertebrata; Mammalia; Treatment; Animal; Plant origin; Spermatophyta
• ISSN: 0378-8741; 1872-7573
• DOI: 10.1016/S0378-8741(03)00073-4

The mistletoe Psittacanthus calyculatus (Loranthaceae) is used in Mexican traditional medicine for the treatment of hypertension. In the present study the effects of a crude ethanolic extract of this mistletoe, on the vasomotor reactivity of superfused rat aortic rings (with or without a functional endothelium) were analyzed. Either in the absence or in the presence of l-NAME or indomethacin, the extract (12.5–800 μg/ml) had no effect on the basal tone of both types of rings. In phenylephrine-precontracted rings, low concentrations of the extract (up to 300 μg/ml) induced a small additional tension development in both types of rings; however, the tension increase was slightly larger in rings having an intact endothelium. At higher concentrations (400–800 μg/ml), the extract relaxed, concentration-dependently, phenylephrine-precontracted rings with an intact endothelium. This relaxation was completely reverted by the addition of l-NAME. When the extract was applied in the continuous presence of l-NAME to phenylephrine-precontracted rings, instead of a relaxation a marked additional tension development occurred. Indomethacin did not modify the relaxation induced by the extract. The results indicate that the ethanolic extract of this mistletoe induces, predominantly, an endothelium-dependent relaxation which seems to be mediated by the synthesis/release of nitric oxide.