Abstract
Aquilaria agallocha Roxb. (Thymelaeceae) heartwood is used in cardiac failure; however, its cardiotonic properties are poorly understood at a pharmacological level. This study investigated methanol extract of A. agallochafor presence of glycosides and its effects on force of contraction, heart rate and coronary flow on rabbit isolated heart. Furthermore, contribution of β1-adrenoceptors and/or L-type Ca2+ channels in A. agallocha-induced cardiac effects was explored. A. agallocha extract, digoxin, verapamil and metoprolol were administered in a retrograde manner. Force of contraction and heart rate were recorded with a force transducer attached to the heart. Coronary flow was measured from collected effluent. The extract induced a significant increase in force of contraction (p<0.001), decrease in heart rate (p<0.05) and coronary flow (p<0.001). Metoprolol (p<0.01) and verapamil (p<0.01) significantly inhibited the plant extract-induced effects. Thus, A. agallocha exhibited cardiotonic effects, most likely via cardiac glycosides, involving ?1-adrenoceptors and L-type Ca2+ channels.
Highlights
Cardiac glycosides remain the drugs of choice in treating congestive heart failure
This study showed that methanol extract of A. agallocha contains cardiac glycosides, which is in complete accordance with the active constituents reported previously (Dash et al, 2008)
The cardiotonic effects produced by methanol extract of A. agallocha most likely can be attributed to glycosides present in it, which is in agreement with an earlier study showing that cardiac glycosides produce positive inotropic effects (Kitada et al, 1987)
Summary
Cardiac glycosides remain the drugs of choice in treating congestive heart failure. their small therapeutic window and myriad of severe adverse effects limit their therapeutic use. To develop safe and effective agents for treating congestive heart failure, plants or their extracts have extensively been investigated for their positive inotropic and negative chronotropic effects. (Fabaceae) (Mohire et al, 2007) and aqueous extract of Berberis lyceum Royle (Berberidaceae) and berberine (Ahmad et al, 2012) have shown positive inotropic and negative chronotropic effects in rat and frog isolated heart preparations. These agents of plant origin most likely produce their effects on heart through a variety of mechanism(s) such as inhibition of Na+/K+-ATPase, potasium channels, β1adrenoceptors and voltage-gated Ca2+ channels. You must attribute the work in the manner specified by the author or licensor
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