Research Article Endothelium/Nitric OxideMediates the Vasorelaxant and Antihypertensive Effects of the Aqueous Extract from the Stem Bark of Mammea africana Sabine (Guttiferae)

Copyright © 2012 Elvine Pami Nguelefack-Mbuyo et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. This study evaluates the vasorelaxant and antihypertensive effects of the aqueous extract from the stem bark of M. africana (AEMA). AEMA was tested in vitro on intact or endothelium-denuded rats ’ aorta rings precontracted with KCl or norepinephrine in absence or in presence of L-NAME or glibenclamide. The effect of a single concentration (300 μg/mL) of AEMA was also examined on the concentration-response curve of KCl. In vivo, the antihypertensive effects of AEMA (200mg/kg/day) were evaluated in male Wistar rats treated with L-NAME (40mg/kg/day) for 4 weeks. AEMA relaxed aorta rings precontracted with NE or KCl with respective EC50 values of 0.36 μg/mL and 197.60 μg/mL. The destruction of endothelium or pretreatment of aorta rings with L-NAME shifted the EC50 of AEMA from 0.36 μg/mL to 40.65 μg/mL and 20.20 μg/mL, respectively. The vasorelaxant activity of M. africana was significantly inhibited in presence of glibenclamide. AEMA also significantly inhibited the concentration-response curve of KCl. Administered orally, AEMA induced acute and chronic antihypertensive effects and normalized renal N