Hypotensive effect of crude extract Olea. africana (Oleaceae) in normo and hypertensive rats.
OBJECTIVE
To investigate the effects of crude extracts of the root and stem of Olea africana on mean arterial pressure (MAP) and heart rate in normo and hypertensive rats.


METHODS
Comparative study.


METHODS
Laboratory.


METHODS
40 Sprague Dawley rats of either sex (150 to 250 g) randomly assigned to normotensive (n = 15) (DOCA) -salt hypertensive (n = 25) groups. The normotensive group comprised three subgroups (n = 5) namely, a control treated with graded volumes of normal saline intravenously (i.v.), and two groups respectively treated with graded doses of aqueous extract of O. africana (i.v.). The hypertensive group comprised five subgroups (n = 5) namely, a control group of sham operated rats, and four groups of nephrectomised rats. One group of nephrectomized rats received Deoxycorticosterone acetate (DOCA) and salt for seven days, while others received DOCAsalt for 14 days. Two groups of the 14 day treated rats respectively received 200 mg/kg and 1,000 mg/kg of O. africana orally thereafter. MAP and HR were measured under sodium pentobarbital anaesthesia (35 mg/kg intraperitoneally).


METHODS
Mean arterial pressure and heart rate.


RESULTS
Intravenous administration of aqueous and ethanolic extracts of O. africana caused an immediate and dose dependent fall in MAP and HR in anaesthetised normotensive rats. The aqueous extract was more potent than the ethanolic extract. Orally administered aqueous extract produced lowering of MAP and HR in DOCA-salt hypertensive rats. Propranolol partially blocked the Map lowering effect of O. africana.


CONCLUSIONS
Extracts of O. africana lowered MAP and HR in normotensive and DOCA-salt hypertensive rats. Hence the use of the aqueous extracts in the treatment of some forms of hypertension and heart palpitations in humans. This effect may be mediated via beta adrenergic receptors.
Osim
E E
EE
Department of Physiology, College of Medical Sciences, University of Calabar, Nigeria.
Mbajiorgu
E F
EF
Mukarati
G
G
Vaz
R F
RF
Makufa
B
B
Munjeri
O
O
Musabayane
C T
CT
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D003900:Desoxycorticosterone; D004195:Disease Models, Animal; D004353:Drug Evaluation, Preclinical; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006973:Hypertension / Q000139:chemically induced / Q000503:physiopathology / Q000628:therapy*; D008297:Male; D016488:Medicine, African Traditional; D010936:Plant Extracts; D010946:Plants, Medicinal; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley
D010936:Plant Extracts; D003900:Desoxycorticosterone