Electrophysiological effects of the aqueous extract of Averrhoa carambola L. leaves on the guinea pig heart

Vasconcelos, Carla Maria Lins de; Araújo, Michely Santos; Conde-Garcia, Eduardo Antônio

doi:10.1016/j.phymed.2005.01.013

Cited by 11 publications

(12 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Averrhoa carambola L., known as star fruit, is a plant of the Oxalidaceae family, a native of Malaysia and actually cultivated there as well as in various other Asian countries and the tropical areas of America, including Brazil, is especially known for its unique, star-like shape and its attractive flavor. In Brazilian traditional medicine, its fruit, juice or tea made from its leaves has been used for its supposed antidiabetic and blood pressure lowering effects, and it is also believed to be an appetite stimulant and an antidiarrheal (Oliveira et al, 1989;Martha et al, 2000;Vicentini et al, 2001;Vasconcelos et al, 2006). Some papers suggest the existence of a neurotoxin in star fruit juice.…”

Section: Introductionmentioning

confidence: 99%

Hypotensive effect of aqueous extract of Averrhoa carambola L. (Oxalidaceae) in rats: An in vivo and in vitro approach

Soncini

Santiago

Orlandi

et al. 2011

Journal of Ethnopharmacology

View full text Add to dashboard Cite

show abstract

Section: Introductionmentioning

confidence: 99%

Hypotensive effect of aqueous extract of Averrhoa carambola L. (Oxalidaceae) in rats: An in vivo and in vitro approach

Soncini

Santiago

Orlandi

et al. 2011

Journal of Ethnopharmacology

View full text Add to dashboard Cite

show abstract

“…When acting on the natural right atrial pacemaker, this extract promoted a signifi cant bradicardia (Vasconcelos et al, 2005). In guinea pig isolated heart, it was observed that AqEx induced different degrees of atrioventricular block (Vasconcelos et al, 2006). It is well known that drugs that reduce the membrane calcium inward current, besides exerting a negative inotropic effect on the myocardium, can also depress the atrial pacemaker activity and reduce the conduction velocity through the atrioventricular node.…”

Section: Discussionmentioning

confidence: 99%

“…Vasconcelos et al (2005) reported that the AqEx of A. carambola leaves exerts a negative inotropic and chronotropic effects on the guinea pig atria. Furthermore, Vasconcelos et al (2006) showed that it decreased the conduction velocity of the atrial impulse and increased the elapsed time to conduct the myocardial impulse from the right atrium to the His bundle. The authors reported that the AqEx induced different degrees of atrioventricular block, prolonged the QT interval, and increased the QRS complex duration.…”

Section: Introductionmentioning

confidence: 99%

Aqueous leaf extract of Averrhoa carambola L. (Oxalidaceae) reduces both the inotropic effect of BAY K 8644 on the guinea pig atrium and the calcium current on GH3cells

Vasconcelos¹,

Gondim

Cruz³

et al. 2008

Rev. bras. farmacogn.

View full text Add to dashboard Cite

RESUMO: "Extrato aquoso das folhas de Averrhoa carambola L. (Oxalidaceae) reduz tanto o efeito inotrópico do BAY K 8644 em átrio de cobaia, quanto a corrente de cálcio em células GH 3 ". Em estudo prévio mostrou-se que o extrato aquoso das folhas de Averrhoa carambola (ExAq) reduziu o inotropismo atrial da cobaia. Por isso, este trabalho avaliou se o ExAq interfere com o infl uxo de cálcio através da membrana celular. A investigação foi conduzida em átrio esquerdo de cobaia, montado em cuba (5 mL, Tyrode, 27 ± 0,1 °C, 95 % O 2 , 5 % CO 2 ), estirado para uma tensão de repouso de 10 mN e submetido a uma estimulação de 2 Hz (0,5 ms, 400 V). O efeito do ExAq sobre a entrada de cálcio nas células foi avaliado em átrio de cobaia e em células GH 3 , estas submetidas a 'patch clamp' na confi guração 'whole cell'. No átrio, o ExAq (1500 μg /mL) deslocou para direita a curva concentração-efeito do (±) BAY K 8644 (agonista dos canais de cálcio tipo-L), aumentando a CE 50 (concentração capaz de produzir 50 % do efeito máximo) de 7,8 ± 0,38 para 115,1 ± 0,44 nM (N = 3, p < 0,05). Em células GH 3 , este extrato (500 μg /mL) reduziu de 282 para 190 pA (30 %) a corrente de cálcio, sem contudo alterar a voltagem de pico da curva desta corrente. Estes resultados mostram que, pelo menos em parte, o efeito inotrópico negativo do ExAq em átrio de cobaia se deve a uma diminuição do infl uxo de cálcio pelos canais tipo-L.Unitermos: Averrhoa carambola, extrato aquoso, corrente de cálcio tipo-L, átrio de cobaia, células GH 3 . ABSTRACT:It was previously showed that aqueous leaf extract (AqEx) of Averrhoa carambola depresses the guinea pig atrial inotropism. Therefore, experiments were carried out on guinea pig left atrium and on pituitary GH 3 cells in order to evaluate the effect of AqEx on the cellular calcium infl ux. The atrium was mounted in an organ chamber (5 mL, Tyrode, 27 ± 0.1 °C, 95 % O 2 , 5 % CO 2 ), stretched to 10 mN, and paced at 2 Hz (0.5 ms, 400 V) and GH 3 cells were submitted to a whole cell voltage clamp confi guration. In the atrium, the AqEx (1500 μg/mL) shifted to the right the concentration-effect curve of the positive inotropic effect produced by (±) BAY K 8644, an L-type calcium channel agonist. The AqEx increased EC 50 (concentration required to promote 50% of the maximum effect) of the inotropic effect of BAY K 8644 from 7.8 ± 0.38 to 115.1 ± 0.44 nM (N = 3; p < 0.05). In GH 3 cells assayed with 500 μg/mL of AqEx, the L-type calcium inward current declined 30 % (from 282 to 190 pA). Nevertheless, the extract did not change the voltage correspondent to the peak current. These data suggest that, at least in part, the negative inotropic effect of AqEx on the guinea pig atrium is due to a reduction of the L-type calcium current.

show abstract

“…As stated by Vasconcelos et al (2006), the electrical wave is slowed down in the heart when the myocardium length constant (λ) is shortened or when the propagated action potential amplitude is reduced, or even in both circumstances. As the amplitude of the action potential of the cells treated with the plant extract remained relatively unchanged, we can assume that the extract did not affect the amplitude of propagated impulses.…”

Section: Discussionmentioning

confidence: 99%

“…Accordingly, it has been demonstrated that the increase of Ri induced a delay in the impulse conduction (Jalife et al, 1989;Fujino et al, 1991, Cascio et al, 2001). According to Vasconcelos et al (2006), the reduction in Rm depends on the opening of potassium K 1 -type channels which leads to the shortening of the QT interval. In the present study the intravenous administration of the extract instead increased the QT interval.…”

Section: Discussionmentioning

confidence: 99%

Cardiovascular Effects of then-Butanol Extract fromKalanchoe CrenataLeaves

Nguelefack

Dimo

Dongmo

et al. 2008

Pharmaceutical Biology

View full text Add to dashboard Cite

The present work examined the effects of the n-butanol extract from the leaves of Kalanchoe crenata (Andrews) Haworth (Crassulaceae) on rat blood pressure and guinea pig papillary muscle contraction and action potential. When administered intravenously at doses of 2, 5, and 10 mg/kg, the n-butanol extract of K. crenata leaves induced a significant transient fall in blood pressure and significantly reduced the cardiac rate for about 10 min. Concomitantly, the extract significantly increased the PR, QRS, and QT intervals of the electrocardiogram (ECG). At concentrations of 300 and 1,000 µg/ml, the n-butanol extract was found to increase the amplitude of electrical contraction of papillary muscle by 137.6 and 223.0%, respectively. When tested on the ventricular myocardiac cell action potential, the extract (100 µg/ml) significantly and time dependently delayed the repolarization without affecting the amplitude. Indeed, the 10%, 60%, and 90% repolarization times were respectively increased by 131.6%, 78.6%, and 52.7%. The bradycardic effect of the n-butanol extract may result from the increase of the PR, QRS, and QT intervals which are in accord with the delay in action potential repolarization observed in in vitro studies. The data obtained in the in vitro studies suggest that K. crenata possess potassium channel blockade properties that may account for its cardiac properties.

show abstract

Electrophysiological effects of the aqueous extract of Averrhoa carambola L. leaves on the guinea pig heart

Cited by 11 publications

References 19 publications

Hypotensive effect of aqueous extract of Averrhoa carambola L. (Oxalidaceae) in rats: An in vivo and in vitro approach

Hypotensive effect of aqueous extract of Averrhoa carambola L. (Oxalidaceae) in rats: An in vivo and in vitro approach

Aqueous leaf extract of Averrhoa carambola L. (Oxalidaceae) reduces both the inotropic effect of BAY K 8644 on the guinea pig atrium and the calcium current on GH3cells

Cardiovascular Effects of then-Butanol Extract fromKalanchoe CrenataLeaves

Contact Info

Product

Resources

About