Cardiodepressive effect elicited by the essential oil of Alpinia speciosa is related to L-type Ca²+ current blockade.
This study was undertaken to elucidate the effect of the essential oil from Alpinia speciosa (EOAs) on cardiac contractility and the underlying mechanisms. The essential oil was obtained from Alpinia speciosa leaves and flowers and the oil was analyzed by GC-MS method. Chemical analysis revealed the presence of at least 18 components. Terpinen-4-ol and 1,8-cineole corresponded to 38% and 18% of the crude oil, respectively. The experiments were conducted on spontaneously-beating right atria and on electrically stimulated left atria isolated from adult rats. The effect of EOAs on the isometric contractions and cardiac frequency in vitro was examined. EOAs decreased rat left atrial force of contraction with an EC₅₀ of 292.2±75.7 μg/ml. Nifedipine, a well known L-type Ca²+ blocker, inhibited in a concentration-dependent manner left atrial force of contraction with an EC₅₀ of 12.1±3.5 μg/ml. Sinus rhythm was diminished by EOAs with an EC₅₀ of 595.4±56.2 μg/ml. Whole-cell L-type Ca²+ currents were recorded by using the patch-clamp technique. EOAs at 25 μg/ml decreased I(Ca,L) by 32.6±9.2% and at 250 μg/ml it decreased by 89.3±7.4%. Thus, inhibition of L-type Ca²+ channels is involved in the cardiodepressive effect elicited by the essential oil of Alpinia speciosa in rat heart.
Laboratório de Biofísica e Farmacologia do Coração, Departamento de Educação - Campus XII, Universidade do Estado da Bahia, Guanambi, Bahia, Brazil.
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Santos
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Roman-Campos
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Carvalho
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Miranda
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Carneiro
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Cavalcante
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Cândido
L Xavier
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Cruz
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Gondim
D032429:Alpinia / Q000737:chemistry*; D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D020746:Calcium Channels, L-Type / Q000187:drug effects* / Q000378:metabolism; D003864:Depression, Chemical; D004305:Dose-Response Relationship, Drug; D005260:Female; D035264:Flowers / Q000737:chemistry; D006321:Heart / Q000187:drug effects; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects*; D009822:Oils, Volatile / Q000737:chemistry / Q000494:pharmacology*; D018408:Patch-Clamp Techniques; D010936:Plant Extracts / Q000737:chemistry*; D018515:Plant Leaves / Q000737:chemistry; D010938:Plant Oils / Q000737:chemistry / Q000494:pharmacology; D010946:Plants, Medicinal / Q000737:chemistry; D051381:Rats
D002121:Calcium Channel Blockers; D020746:Calcium Channels, L-Type; D009822:Oils, Volatile; D010936:Plant Extracts; D010938:Plant Oils