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Nigerian Journal of Natural Products and Medicine

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PHARMACOLOGY OF AFRICAN MEDICINAL PLANTS: NEURO MUSULAR AND CARDIOVASCULAR PROPERTIES OF SEGURIDACA LONGIPENDUNCULATA

JAO Ojewole, ORS Ilesanmi, Olayiwola Gbola

Abstract


The neuromuscular and cardiovascular properties of 60% methanol extract of the root bark of Securidaca longipedunculata (Fresen.) have been examined in vitro and in vivo, using laboratory anaimal models. The extract (MESL) at 50-250 mg/ml inhibited or abolished contractions of the frog rectus abdominis muscle preparations induced by acetycholine (Ach), arbachol, or nicotine (0.1-10mg/ml) in a dose dependent manner. The same concentrations of the extract always depressed or a bolished indirect or direct electrical stimulation-induced maximal twitches of the chick biventer or rat hemidiaphragm muscle preparations in a concentration-related manner. MESL provoked neuromuscular blockade was only partially reversed by physostigmine (PHY, 5-10mg/ml), which rapidly and completely reversed the neuromuscular blockade, instituted by d-tubocurarine (dTC, 1-10mg/ml). Nevertheless, exogenous administration of calcium (Ca2+), 30-40 mM) to the bathing physiological fluid rapidly and completely reversed MESL-induced neuromuscular blockade. MESL (50-250 mg/ml) potentiated the depressant effects of d-tubocurarine on electrically-evoked twitches of all the skeletal muscle preparations examined, and the caused recurarisation of partially-curarised muscles, MESL (1-250mg/ml) also induced negative inotropic and chronotropic responses in guinea-pig isolated atrial muscle strips, and reduced or abolished, in a non-specific manner, the positive inotropic and chronotropic effectgs of isoprenaline or noradrenaline (0.001-1.0mg/ml), and calcium (Ca2+), 5-40mM), in a concentration-related manner. The negative inotropic and chronotropic effects of the extract on guinea-pig atrial muscle preparations were not modfified by exogenous administration of atropine (AT, 0.1-2.0 mg/ml) to the bathing fluid. MESL (1-250 mg/kg, i.v.) dose-dependently reduced the heart rate and systemic arterial blood pressure of anaesthetized rats. The depressor effects of the extract on the cardiovascular parameters studied were not affectd by atropinization. However, the extract (5-250mg/kg, i.v.) dose-dependently inhibited (or abolished) the pressor effects of noradrenaline (0.01-1.0 ug/kg, i.v.) on the arterial blood pressure and heart rate of the anaesthesized rats.

Key Words: Securidaca longipedunculata; Polygalaceae; Root Bark; Methanolic Extract; Neuromuscular and Cardiovascular Properties

Nig. J. Nat Prod. And Med. Vol.4 2000:30-36



http://dx.doi.org/10.4314/njnpm.v4i1.11734
AJOL African Journals Online