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CRINUM GLAUCUM AQUEOUS EXTRACT POSSESES CALCIUM
ANTAGONISTIC PROPERTIES
Okpe, S.O. and Adeyemi O.O
Department of Pharmacology &
Toxicology University of Benin, P.M.B 1154
Benin City 300001, Nigeria.
E-mail: steveokpo@uniben.edu
Department of Pharmacology,
College of Medicine, University of Lagos, P.M.B.
12003, Lagos, Nigeria
E-mail: ooadey@yahho.com
ABSTRACT
The aqueous bulb extract of
Crinum glaucum is used locally as an antispasmodic in various
ailments such as asthma, convulsions etc. The aim of this study was to
determine whether the various observed activities of Crinum glaucum
could be related to calcium blocking mechanism or other more direct
mechanism. Cumulative adition of the aqueous extract (1-8mg/ml) produced
an initial transient relaxation and a concentration dependent inhibition
of spontaneous activity of the isolated rabbite jejunum, which was
completely abolished at the highest concentration of the extract.
Pretreatment of the produced by CaCl2, in a
calcium-free Tyrode solution, an effect similar to that of verapamil
(3x10-7M). On the spontaneously beating rat atria, the
extract produced a concentration –dependent decrease in heart rate, an
initial increase in force, at low concentrations (0.5 and 1mg/ml) of
the extract of the extract and a concentration-dependent reduction at
the high concentrations. The inhibitory effect of the extract on both
force and rate of atrial contractions was restored by increasing the
extracellular calcium (20Mm) but not antagonized by artropine (3x10-6M
) showing that it is not a cholinergic effect. A rightward shift of the
CaCl2 concentration-responses curve was also produced by the
extract (4mg/ml). The extract (1-20mg/ml) caused a
concentration-dependent inhibition of both force and rate of contraction
of the isolated rabbit heart, which were not antagonized by atropine but
reversed by calcium chloride. The extract (1-16mg/ml) also produced
significant non-competitive, concentration-dependent and rightward
shifts of noradrenaline (10-9 – 4x10-7M) and KCI
(10-80Mm) concentyration-response curvses on the rat proximal aorta.
These results suggest that the aqueous extract of Crinum glaucum
mediates it effects on the smooth and cardiac muscles by affecting
calcium movement.
Keywords: Rat
aorta, verapamil, rabbit jejunum, calcium-free tyrode |
