The positive inotropic effect of the ethyl acetate fraction from Erythrina velutina leaves on the mammalian myocardium : the role of adrenergic receptors.
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2013
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Objectives 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 mm), nifedipine (1 mm) 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.
Key findings EAcF (550 mg/ml) had a positive inotropic effect, increasing the
atrial force by 164% (EC50 = 157 44 mg/ml, n = 6), but it was less potent than
isoproterenol (EC50 = 0.0036 0.0019 mg/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.
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Contractility, Myocardium
Citação
PASSOS, A. G. S. et al. The positive inotropic effect of the ethyl acetate fraction from Erythrina velutina leaves on the mammalian myocardium: the role of adrenergic receptors. Journal of Pharmacy and Pharmacology, v. 65, p. 928-936, 2013. Disponível em: <http://onlinelibrary.wiley.com/doi/10.1111/jphp.12052/abstract>. Acesso em: 10 jan. 2017.