Anti-hypertensive effects of the methanol/methylene chloride stem bark extract of Mammea africana in l-NAME-induced hypertensive rats.
OBJECTIVE
The methanol/methylene chloride (CH(3)OH/CH(2)Cl(2)) extract from the stem bark of Mammea africana was showed to possess vasodilating effect in the presence and the absence of N(omega)-nitro-l-arginine methyl ester (l-NAME). The present study was designed to evaluate the effects of the methanol/methylene chloride from the stem bark of Mammea africana.


METHODS
The extract (200 mg/(kg day)) was administered orally in rats treated concurrently with l-NAME (40 mg/(kg day)). l-Arginine (100 mg/(kg day)) and captopril (20 mg/(kg day))were used as positive controls. Bodyweight, systolic arterial blood pressure and heart rate were measured weekly throughout the experiment period (28 days). At the end of treatment, animals were killed and the cardiac mass index evaluated. The aorta was used to evaluate the endothelium-dependant relaxation to carbachol. The aorta contraction induced by noradrenalin was also examined and expressed as a percentage of that induced by KCl.


RESULTS
The extract neither affected the body weight nor the heart rate. The extract as captopril completely prevented the development of arterial hypertension. Both the substances failed to restore the endothelium-dependent vascular relaxation and increased the vascular contraction to norepinephrine in relation to KCl contraction. They also significantly reduced the left ventricular hypertrophy induced by l-NAME.


CONCLUSIONS
These findings are in agreement with the traditional use of Mammea africana in the treatment of arterial hypertension and indicate that it may have a beneficial effect in patients with NO deficiency but will be unable to improve their endothelium-dependent vasorelaxation.
Nguelefack-Mbuyo
P E
PE
Department of Animal Biology and Physiology, Laboratory of Animal Physiology, University of Yaounde I, BP 812 Yaounde, Cameroon.
Nguelefack
T B
TB
Dongmo
A B
AB
Afkir
S
S
Azebaze
A G B
AG
Dimo
T
T
Legssyer
A
A
Kamanyi
A
A
Ziyyat
A
A
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D001835:Body Weight / Q000187:drug effects; D002217:Carbachol / Q000494:pharmacology; D004791:Enzyme Inhibitors; D006339:Heart Rate / Q000187:drug effects; D006973:Hypertension / Q000139:chemically induced / Q000188:drug therapy* / Q000503:physiopathology; D008297:Male; D031252:Mammea / Q000737:chemistry*; D000432:Methanol; D008752:Methylene Chloride; D018721:Muscarinic Agonists / Q000494:pharmacology; D009131:Muscle, Smooth, Vascular / Q000187:drug effects; D009206:Myocardium / Q000473:pathology; D019331:NG-Nitroarginine Methyl Ester; D009929:Organ Size / Q000187:drug effects; D008517:Phytotherapy; D024301:Plant Bark / Q000737:chemistry; D010936:Plant Extracts / Q000627:therapeutic use; D018547:Plant Stems / Q000737:chemistry; D051381:Rats; D017208:Rats, Wistar; D012997:Solvents
D004791:Enzyme Inhibitors; D018721:Muscarinic Agonists; D010936:Plant Extracts; D012997:Solvents; D008752:Methylene Chloride; D002217:Carbachol; D019331:NG-Nitroarginine Methyl Ester; D000432:Methanol