title: The positive inotropic effect of the ethyl acetate fraction from Erythrina velutina leaves on the mammalian myocardium: the role of adrenergic receptors.
abstract: OBJECTIVE
  We studied the effects of ethyl acetate fraction (EAcF) obtained from Erythrina velutina leaves on mammalian myocardium.
  
  
  METHODS
  The effect of EAcF on the contractility was studied using guinea-pig left atria mounted in a tissue bath (Tyrode's solution, 29°C, 95% CO2 , 5% O2 ) and electrically stimulated (1 Hz). Concentration-response curves of EAcF were obtained in the presence of propranolol (1 μm), nifedipine (1 μm) and in reserpinized animals (5 mg/kg). The involvement of l-type calcium current (ICa,L ) on the EAcF effect was observed in cardiomyocytes of mice assessed using patch-clamp technique.
  
  
  RESULTS
  EAcF (550 μg/ml) had a positive inotropic effect, increasing the atrial force by 164% (EC50  = 157 ± 44 μg/ml, n = 6), but it was less potent than isoproterenol (EC50  = 0.0036 ± 0.0019 μg/ml, n = 8). The response evoked by EAcF was abolished by propranolol or nifedipine. Reserpine did not alter the inotropic response of EAcF. Furthermore, an enhancement of the ICa,L peak (31.2%) with EAcF was observed. Chemical analysis of EAcF revealed the presence of at least 10 different flavonoid glycoside derivatives. Two were identified as vicenin II and isorhoifolin.
  
  
  CONCLUSIONS
  We conclude that EAcF increases the cardiac contractile force by increasing the l-type calcium current and activating the adrenergic receptor pathway.
authors: Departamento de Fisiologia, Universidade Federal de Sergipe, São Cristóvão, Brazil.
authors: Amilton Gustavo da Silva
authors: AG
authors: Passos
authors: Antônio Nei Santana
authors: AN
authors: Gondim
authors: Danilo
authors: D
authors: Roman-Campos
authors: Jader Santos
authors: JS
authors: Cruz
authors: Eduardo Antônio
authors: EA
authors: Conde-Garcia
authors: Vítor
authors: V
authors: Araújo Neto
authors: Charles Santos
authors: CS
authors: Estevam
authors: Sandra Valéria Santos
authors: SV
authors: Cerqueira
authors: Geraldo Célio
authors: GC
authors: Brandão
authors: Alaíde Braga
authors: AB
authors: Oliveira
authors: Carla Maria Lins de
authors: CM
authors: Vasconcelos
mesh_terms: D000085:Acetates / Q000737:chemistry*; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002316:Cardiotonic Agents / Q000494:pharmacology*; D002395:Catecholamines / Q000378:metabolism; D004895:Erythrina / Q000737:chemistry*; D005260:Female; D006168:Guinea Pigs; D006321:Heart / Q000187:drug effects*; D006325:Heart Atria / Q000187:drug effects* / Q000378:metabolism; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D008322:Mammals / Q000378:metabolism; D009119:Muscle Contraction / Q000187:drug effects; D009206:Myocardium / Q000378:metabolism; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology; D018515:Plant Leaves / Q000737:chemistry; D011941:Receptors, Adrenergic / Q000378:metabolism*
chemical_list: D000085:Acetates; D002316:Cardiotonic Agents; D002395:Catecholamines; D010936:Plant Extracts; D011941:Receptors, Adrenergic; C007650:ethyl acetate; D007545:Isoproterenol; D002118:Calcium