title: Hypotensive and antihypertensive effects of a hydroalcoholic extract from Senecio nutans Sch. Bip. (Compositae) in mice: Chronotropic and negative inotropic effect, a nifedipine-like action.
abstract: BACKGROUND
  Senecio nutans Sch. Bip. (Compositae) is an endemic plant of South America used in the management of acute mountain sickness in the Andean communities. Currently, the direct effects of hydroalcoholic extract from S. nutans on the cardiovascular system are unknown. The aim of this study was to determine the effects and mechanism of action of S. nutans on cardiovascular function in normotensive and Angiotensin II (1μg/mL) hypertension mice models.
  
  
  METHODS
  Blood pressure and ECG measurements were simultaneously carried out on the mice and rats. The isolated right atrium, papillary muscle of the left ventricle and isolated heart of rat were used to study the cardiac functions and mechanisms.
  
  
  RESULTS
  S. nutans (40mg/Kg) induced a 30% and 12% significant (p<0.05) reduction of the mean arterial pressure (MAP) in normotensive and hypertensive mice respectively. This decrease was as a result of decrease in heart rate (HR) in normotensive (25%) and hypertensive model (31%). It also decreased the sinus rhythm in isolated right atrium of rat. Compared with Losartan, a known anti-hypertensive, S. nutans caused a dose-dependent negative inotropic effect (dP/dtmax) on Langendorff isolated heart system. While Losartan, decreased the MAP by 30% but had no effect on heart rate. The calcium blocker nifedipine had similar effects as S. nutans, decreasing the beat frequency of isolated right atrium and contractility of papillary muscle of the left ventricle of rat.
  
  
  CONCLUSIONS
  The results suggest an important clinical function in hypertension therapy, as S. nutans could decrease the blood pressure in hypertensive mice by decreasing the HR and contractility, leading to a reduction in myocardial oxygen demand.
authors.affiliation: Experimental Physiology Laboratory (EPhyL), and.
authors.forename: Fredi
authors.initials: F
authors.lastname: Cifuentes
authors.affiliation: Laboratorio de Química Biológica, Instituto Antofagasta (IA), Universidad de Antofagasta, Antofagasta, Chile.
authors.forename: Adrián
authors.initials: A
authors.lastname: Paredes
authors.affiliation: Departamento de Ciencias Químicas y Farmacéuticas, Facultad de Ciencias de la Salud, Universidad Arturo Prat, Iquique, Chile. Electronic address: clpalaci@unap.cl.
authors.forename: Javier
authors.initials: J
authors.lastname: Palacios
authors.affiliation: Experimental Physiology Laboratory (EPhyL), and.
authors.forename: Fernanda
authors.initials: F
authors.lastname: Muñoz
authors.affiliation: Experimental Physiology Laboratory (EPhyL), and.
authors.forename: Lorena
authors.initials: L
authors.lastname: Carvajal
authors.affiliation: Department of Basic Medical Sciences Physiology Section, Faculty of Medical Sciences, The University of the West Indies, Mona, Kingston 7, Jamaica, W.I.
authors.forename: Chukwuemeka R
authors.initials: CR
authors.lastname: Nwokocha
authors.affiliation: Laboratorio de Química Biológica, Instituto Antofagasta (IA), Universidad de Antofagasta, Antofagasta, Chile.
authors.forename: Glauco
authors.initials: G
authors.lastname: Morales
mesh_terms: D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology* / Q000627:therapeutic use; D001794:Blood Pressure / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004562:Electrocardiography / Q000187:drug effects; D020834:Ethnopharmacology; D006325:Heart Atria / Q000187:drug effects; D006339:Heart Rate / Q000187:drug effects*; D006973:Hypertension / Q000188:drug therapy*; D019808:Losartan / Q000494:pharmacology / Q000627:therapeutic use; D008297:Male; D051379:Mice; D009200:Myocardial Contraction / Q000187:drug effects*; D009543:Nifedipine / Q000494:pharmacology* / Q000627:therapeutic use; D010210:Papillary Muscles / Q000187:drug effects; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology*; D051381:Rats; D012674:Senecio / Q000737:chemistry*
chemical_list: D000959:Antihypertensive Agents; D010936:Plant Extracts; D009543:Nifedipine; D019808:Losartan
keywords: Blood pressure; Contractility; Extract plant; Heart rate; Hypertension; Mice