title: Cardiovascular effects of ginger aqueous extract and its phenolic constituents are mediated through multiple pathways.
abstract: Ginger is a world known food plant which is equally reputed for its medicinal properties. We report here the hypotensive, endothelium-dependent and independent vasodilator and cardio-suppressant and stimulant effects of its aqueous extract (Zo.Cr). Zo.Cr, which tested positive for saponins, flavonoids, amines, alkaloids and terpenoids, induced a dose-dependent (3.0-10.0 mg/kg) fall in the arterial blood pressure (BP) of anaesthetized rats which was partially blocked by atropine (1 mg/kg). In isolated endothelium-intact rat aorta, Zo.Cr (0.01-5.0 mg/ml) relaxed the phenylephrine (1 microM)-induced contractions, effect partially blocked by atropine (1 microM). Zo.Cr inhibited the K+ (80 mM)-induced contractions and also shifted the Ca++ dose-response curves to the right, similar to verapamil, indicating Ca++ antagonist activity. An atropine-resistant and l-NAME-sensitive vasodilator activity was also noted from ginger phenolic constituents 6-, 8- and 10-gingerol, while 6-shogaol showed a mild vasodilator effect. In guinea-pig atria, Zo.Cr (0.1-5.0 mg/ml) inhibited the force and rate of atrial contractions. Pretreatment with atropine blocked the inhibitory effect and a stimulatory effect was unmasked which was resistant to propranolol and verapamil but sensitive to ryanodine, blocker of Ca++ release from intracellular stores. Later at doses >or=1.0 mg/ml, the extract completely suppressed the atrial tissue, effect resistant to glibenclamide, pyrilamine, aminophylline and L-NAME. These data indicate that the aqueous ginger extract lowers BP through a dual inhibitory effect mediated via stimulation of muscarinic receptors and blockade of Ca++ channels and this study provides sound mechanistic basis for the use of ginger in hypertension and palpitations.
authors.affiliation: Department of Biological and Biomedical Sciences, The Aga Khan University Medical College, Karachi 74800, Pakistan.
authors.forename: Muhammad Nabeel
authors.initials: MN
authors.lastname: Ghayur
authors.forename: Anwarul Hassan
authors.initials: AH
authors.lastname: Gilani
authors.forename: Maria B
authors.initials: MB
authors.lastname: Afridi
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Houghton
mesh_terms: D000758:Anesthesia; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects; D001794:Blood Pressure / Q000187:drug effects; D002118:Calcium / Q000037:antagonists & inhibitors; D002317:Cardiovascular Agents; D002396:Catechols / Q000494:pharmacology; D002855:Chromatography, Thin Layer; D004305:Dose-Response Relationship, Drug; D005233:Fatty Alcohols / Q000494:pharmacology; D005260:Female; D020939:Zingiber officinale / Q000737:chemistry*; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008297:Male; D009569:Nitric Oxide / Q000378:metabolism; D010636:Phenols / Q000494:pharmacology*; D010936:Plant Extracts / Q000494:pharmacology; D018517:Plant Roots / Q000737:chemistry; D051381:Rats
chemical_list: D002317:Cardiovascular Agents; D002396:Catechols; D005233:Fatty Alcohols; D010636:Phenols; D010936:Plant Extracts; D009569:Nitric Oxide; C040115:shogaol; C007845:gingerol; D002118:Calcium