title: Blood pressure lowering and vasomodulator effects of piperine.
abstract: This study was aimed to explore underlying mechanism(s) of cardiovascular effects of piperine. Intravenous administration of piperine caused a dose-dependent (1 to 10 mg/kg) decrease in mean arterial pressure (MAP) in normotensive anesthetized rats; the next higher dose (30 mg/kg) did not cause any further change in MAP. The fall in blood pressure (BP) was followed by small increase in MAP after each dose. In Langendorrf's rabbit heart preparation, piperine caused partial inhibition and verapamil caused complete inhibition of force and rate of ventricular contractions and coronary flow. In rabbit aortic rings, piperine inhibited high K+ (80 mM) precontractions and partially inhibited phenylephrine (PE), suggesting Ca2+ channel blockade (CCB), which was further confirmed when pretreatment of tissues with piperine caused rightward shift in Ca2+ concentration-response curves, similar to verapamil. In Ca2+-free medium, piperine (1 to 30 microM) exhibited vasoconstrictor effect. In rat aorta, piperine demonstrated endothelium-independent vasodilator effect and was more potent against high K+ precontractions than PE. In bovine coronary artery preparations, piperine inhibited high K+ precontractions completely. These data indicate that piperine possesses a blood pressure-lowering effect mediated possibly through CCB, while consistent decrease in BP was restricted by associated vasoconstrictor effect. Additionally, species selectivity exists in the CCB effect of piperine.
authors.affiliation: Department of Pharmaceutical Sciences; Federal Urdu University of Arts, Science and Technology, Gulshan Campus Karachi-75300, Pakistan.
authors.forename: Syed Intasar Husain
authors.initials: SI
authors.lastname: Taqvi
authors.forename: Abdul Jabbar
authors.initials: AJ
authors.lastname: Shah
authors.forename: Anwarul Hassan
authors.initials: AH
authors.lastname: Gilani
mesh_terms: D000470:Alkaloids / Q000008:administration & dosage / Q000302:isolation & purification / Q000494:pharmacology*; D000818:Animals; D000959:Antihypertensive Agents / Q000008:administration & dosage / Q000302:isolation & purification / Q000494:pharmacology*; D001013:Aorta, Thoracic / Q000187:drug effects; D052117:Benzodioxoles / Q000008:administration & dosage / Q000302:isolation & purification / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects*; D002417:Cattle; D003326:Coronary Circulation / Q000187:drug effects; D003331:Coronary Vessels / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D066298:In Vitro Techniques; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects*; D029222:Piper nigrum / Q000737:chemistry; D010880:Piperidines / Q000008:administration & dosage / Q000302:isolation & purification / Q000494:pharmacology*; D053284:Polyunsaturated Alkamides / Q000008:administration & dosage / Q000302:isolation & purification / Q000494:pharmacology*; D011817:Rabbits; D051381:Rats; D017207:Rats, Sprague-Dawley; D014664:Vasodilation / Q000187:drug effects*
chemical_list: D000470:Alkaloids; D000959:Antihypertensive Agents; D052117:Benzodioxoles; D010880:Piperidines; D053284:Polyunsaturated Alkamides; C008922:piperine