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JAO Ojewole
CO Adewunmi


This study was designed to examine some cardiovascular effects of garlic [Allium sativum (Linn.) bulb] methanolic extract in experimental mammals with a view to shedding more light on the plausible mechanisms of the cardiovascular actions of the herb. Garlic methanolic extract (GME, 50 — 800 mg/ml) significantly (P<0.05 — 0.001) reduced or abolished, in a concentration-dependent manner, the positive inotropic and chronotropic responses of guinea-pig isolated atrial muscle preparations induced by nordrenaline or isoprenaline (1-100mM), and calcium (Ca2+, 5 — 40 mM). The negative inotropic and chronotropic effects of plant extract on guinea-pig atrial muscle strips were not modified by exogenous administration of atropine (7.5x107 —2.5x106M) to the bath fluid. Furthermore, the plant extract (GME), 50 — 800 mg/ml) significantly inhibited (P<0.05 — 0.001) or abolished, in a concentration-relaxed fashion, the spontaneous, myogenic contractions of the rat isolated portal vein. At the same concentration level, the plant extract (GME, 50 — 800 mg/ml) significantly reduced (P<0.05-0.001) or abolished in a concentration-dependent manner, contractions of the rat isolated aortic rings and portal veins sproduced by exogenous administration of noradrenaline (1-100mM). Moreover, garlic methanolic extract (GME, 50 — 800 mg/kg p.o.) dose-dependently and significantly (P<0.05-0.001) reduced systemic arterial blood pressures and heart rates normotensive and renovascular hypertensive rats. The cardiodepressant effect of the herb is thought to be due, at least in part, to β1-adrenoceptor blockade, and partly also, as a consequence of its non-specific spamolytic action.

Key Words: Garlic (Allium sativum bulb) Methanolic Extract; Mammals: Negative Inotropic and Chronotropic Responses: β1

Nig. J. Nat Prod. And Med. Vol.5 2001: 20-25