Document Detail

Inotropic effects of extracts of Psidium guajava L. (guava) leaves on the guinea pig atrium.
MedLine Citation:
PMID:  12715086     Owner:  NLM     Status:  MEDLINE    
Many pharmacological effects have been ascribed to extracts of Psidium guajava L. (guava) leaves. However, in spite of its widespread use in Brazilian folk medicine and a reasonable number of scientific reports about it, we could not find any study dealing with its action on the mammalian myocardium. In the present study, by measuring isometric force, we observed that the crude extract of P. guajava (water-alcohol extract obtained by macerating dry leaves) depresses the guinea pig atrial contractility in a concentration-dependent fashion (N = 8 hearts, 15 trials). The compound with cardiac activity was concentrated by extraction in a Soxhlet apparatus using 17 M glacial acetic acid after removing the less polar fractions (hexane, chloroform, acetone, ethanol and methanol), suggesting that this compound is a highly polar substance. In the isolated guinea pig left atrium the acetic acid fraction (10-800 mg/l) of P. guajava 1) reversibly decreased myocardial force in a concentration-dependent fashion (EC50 = 0.07g/l, N = 5 hearts, 9 trials, P<0.05), 2) increased the atrial relaxation time measured at 20% of the force amplitude up to 35% (91 +/- 15 to 123 +/- 30 ms, N = 3 hearts, 6 trials, P<0.05), 3) abolished the positive staircase effect (Bowditch phenomenon) in a concentration-dependent fashion suggesting a decrease of the cellular inward calcium current (N = 4 hearts, 8 trials, P<0.05), and 4) its inotropic effect was abolished by cholinergic receptor blockade with 1.5 mM atropine sulfate, indicating a cholinergic involvement in the mechanism of action of the extract (N = 7 hearts, 15 trials, P<0.05). The acetic acid extract was 20 times more potent than crude extract (EC50 = 1.4 g/l). The results showed that extracts from P. guajava leaves depress myocardial inotropism.
E A Conde Garcia; V T Nascimento; A B Santiago Santos
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2003-04-22
Journal Detail:
Title:  Brazilian journal of medical and biological research = Revista brasileira de pesquisas médicas e biológicas / Sociedade Brasileira de Biofísica ... [et al.]     Volume:  36     ISSN:  0100-879X     ISO Abbreviation:  Braz. J. Med. Biol. Res.     Publication Date:  2003 May 
Date Detail:
Created Date:  2003-04-25     Completed Date:  2003-12-17     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  8112917     Medline TA:  Braz J Med Biol Res     Country:  Brazil    
Other Details:
Languages:  eng     Pagination:  661-8     Citation Subset:  IM    
Laboratório de Biofísica dos Tecidos Excitáveis, Departamento de Fisiologia, Centro de Ciências Biológicas e da Saúde, Universidade Federal de Sergipe, São Cristóvão, SE, Brasil.
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MeSH Terms
Cardiotonic Agents / pharmacology*
Guinea Pigs
Heart Atria / drug effects
Myocardial Contraction / drug effects*
Plant Extracts / pharmacology
Plant Leaves
Plants, Medicinal
Reg. No./Substance:
0/Cardiotonic Agents; 0/Plant Extracts

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