title: Radish seed extract mediates its cardiovascular inhibitory effects via muscarinic receptor activation.
abstract: In this study, we describe the hypotensive, cardio-modulatory and endothelium-dependent vasodilator actions of Raphanus sativus (radish) seed crude extract in an attempt to provide scientific basis for its traditional use in hypertension. The plant extract (Rs.Cr) was prepared in distilled water and was subjected to phytochemical screening using standard analytical procedures. In vivo blood pressure was monitored in anaesthetized normotensive rats. Isolated tissue preparations were suspended in tissue baths containing Kreb's solution while acute toxicity study was performed in mice for 24 h. Rs.Cr tested positive for the presence of saponins, flavonoids, tannins, phenols and alkaloids and caused a dose-dependent (0.1-3 mg/kg) fall in blood pressure and heart rate of rats that was mediated via an atropine-sensitive pathway. In isolated guinea-pig atria, Rs.Cr showed dose-dependent (0.03-3.0 mg/mL) inhibition of force and rate of contractions. In the atropine-treated tissues, the inhibitory effect was abolished and a cardiac stimulant effect was unmasked which was resistant to adrenergic and serotonergic receptor blockade. In the endothelium-intact rat aorta, Rs.Cr inhibited phenylephrine-induced contractions, which was blocked by atropine and Nomega-Nitro-L-arginine methyl ester hydrochloride while was also absent in the endothelium-denuded preparations. The extract was safe in mice up to the dose of 10 g/kg. The study shows that the cardiovascular inhibitory effects of the plant are mediated through activation of muscarinic receptors thus possibly justifying its use in hypertension.
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
mesh_terms: D000818:Animals; D000959:Antihypertensive Agents / Q000737:chemistry / Q000494:pharmacology*; D001013:Aorta, Thoracic / Q000187:drug effects / Q000378:metabolism; D001285:Atropine / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D006168:Guinea Pigs; D006325:Heart Atria / Q000187:drug effects / Q000378:metabolism; D006339:Heart Rate / Q000187:drug effects; D066298:In Vitro Techniques; D018727:Muscarinic Antagonists / Q000494:pharmacology; D009200:Myocardial Contraction; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology*; D031224:Raphanus; D051381:Rats; D017207:Rats, Sprague-Dawley; D011976:Receptors, Muscarinic / Q000187:drug effects* / Q000378:metabolism; D012639:Seeds; D014664:Vasodilation
chemical_list: D000959:Antihypertensive Agents; D018727:Muscarinic Antagonists; D010936:Plant Extracts; D011976:Receptors, Muscarinic; D001285:Atropine