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Pharm Biol. 2012 Nov;50(11):1436-41. doi: 10.3109/13880209.2012.684690. Epub 2012 Sep 11.

Possible mechanisms of action of the hypotensive effect of Annona muricata (soursop) in normotensive Sprague-Dawley rats.

Author information

1
Department of Basic Medical Sciences (Physiology Section), The University of the West Indies, Mona, Kingston 7, Jamaica. chukwuemeka.nwokocha@uwimona.edu.jm

Abstract

CONTEXT:

Annona muricata Linn (Annonaceae) (soursop) is a food plant reported to have antihypertensive properties.

OBJECTIVE:

We investigated the blood pressure reducing effect of its aqueous leaf extract and the possible mechanisms that may be responsible.

METHODS:

Intravenous administration of an aqueous leaf extract (9.17-48.5 mg/kg) of A. muricata on the mean arterial pressure and heart rate were recorded invasively on anaesthetized, normotensive Sprague-Dawley rats. Contractile responses of rat aortic rings to the extract (0.5-4.0 mg/mL) were studied using standard organ bath techniques.

RESULTS:

A. muricata (9.17-48.5 mg/kg) caused significant (p < 0.05) dose-dependent reduction in blood pressure without affecting the heart rates. The hypotensive effects were unaffected by atropine (2 mg/kg), mepyramine (5 mg/kg), propranolol (1 mg/kg) and L-NAME (5 mg/kg). A. muricata leaf aqueous extract significantly (p < 0.05) relaxed phenylephrine (10(-9)-10(-4) M) and 80 mM KCl induced contractions in endothelium intact and denuded aortic rings; and caused a significant (p < 0.05) rightward shift of the Ca(2+) dose response curves in Ca(2+)-free Kreb's solution containing 0.1 mM EGTA.

CONCLUSIONS:

The hypotensive effects of A. muricata are not mediated through muscarinic, histaminergic, adrenergic and nitric oxide pathways, but through peripheral mechanisms involving antagonism of Ca(2+).

PMID:
22950673
DOI:
10.3109/13880209.2012.684690
[Indexed for MEDLINE]

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