title: Roselle Polyphenols Exert Potent Negative Inotropic Effects via Modulation of Intracellular Calcium Regulatory Channels in Isolated Rat Heart.
abstract: Roselle (Hibiscus sabdariffa Linn.) calyces have demonstrated propitious cardioprotective effects in animal and clinical studies; however, little is known about its action on cardiac mechanical function. This study was undertaken to investigate direct action of roselle polyphenols (RP) on cardiac function in Langendorff-perfused rat hearts. We utilized RP extract which consists of 12 flavonoids and seven phenolic acids (as shown by HPLC profiling) and has a safe concentration range between 125 and 500 μg/ml in this study. Direct perfusion of RP in concentration-dependent manner lowered systolic function of the heart as shown by lowered LVDP and dP/dtmax, suggesting a negative inotropic effect. RP also reduced heart rate (negative chronotropic action) while simultaneously increasing maximal velocity of relaxation (positive lusitropic action). Conversely, RP perfusion increased coronary pressure, an indicator for improvement in coronary blood flow. Inotropic responses elicited by pharmacological agonists for L-type Ca2+channel [(±)-Bay K 8644], ryanodine receptor (4-chloro-m-cresol), β-adrenergic receptor (isoproterenol) and SERCA blocker (thapsigargin) were all abolished by RP. In conclusion, RP elicits negative inotropic, negative chronotropic and positive lusitropic responses by possibly modulating calcium entry, release and reuptake in the heart. Our findings have shown the potential use of RP as a therapeutic agent to treat conditions like arrhythmia.
authors.affiliation: Programme of Biomedical Science, School of Diagnostic and Applied Health, Faculty of Health Sciences, Universiti Kebangsaan Malaysia, Jalan Raja Muda Abdul Aziz, 50300, Kuala Lumpur, Malaysia.
authors.forename: Yi-Cheng
authors.initials: YC
authors.lastname: Lim
authors.affiliation: Programme of Biomedical Science, School of Diagnostic and Applied Health, Faculty of Health Sciences, Universiti Kebangsaan Malaysia, Jalan Raja Muda Abdul Aziz, 50300, Kuala Lumpur, Malaysia.
authors.forename: Siti Balkis
authors.initials: SB
authors.lastname: Budin
authors.affiliation: Department of Anatomy, Faculty of Medicine, Universiti Kebangsaan Malaysia Medical Center, Jalan Yaacob Latif, Bandar Tun Razak, 56000, Cheras, Kuala Lumpur, Malaysia.
authors.forename: Faizah
authors.initials: F
authors.lastname: Othman
authors.affiliation: School of Chemical Sciences and Food Technology, Faculty of Sciences and Technology, Universiti Kebangsaan Malaysia, 43600, Bangi, Selangor, Malaysia.
authors.forename: Jalifah
authors.initials: J
authors.lastname: Latip
authors.affiliation: Programme of Biomedical Science, School of Diagnostic and Applied Health, Faculty of Health Sciences, Universiti Kebangsaan Malaysia, Jalan Raja Muda Abdul Aziz, 50300, Kuala Lumpur, Malaysia. satirah@ukm.edu.my.
authors.forename: Satirah
authors.initials: S
authors.lastname: Zainalabidin
mesh_terms: D000818:Animals; D002118:Calcium / Q000502:physiology; D020013:Calcium Signaling / Q000187:drug effects* / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D006321:Heart / Q000187:drug effects* / Q000502:physiology; D031584:Hibiscus; D007424:Intracellular Fluid / Q000187:drug effects / Q000502:physiology; D000067268:Isolated Heart Preparation / Q000379:methods*; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects* / Q000502:physiology; D010936:Plant Extracts / Q000302:isolation & purification / Q000494:pharmacology; D059808:Polyphenols / Q000302:isolation & purification / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D010936:Plant Extracts; D059808:Polyphenols; D002118:Calcium
keywords: Calcium channels; Chronotropic; Heart; Hibiscus sabdariffa Linn.; Inotropic; Polyphenols