ANTICALCIC EFFECT OF AN AQUEOUS TRUNK BARK EXTRACT OF PARKIA BIGLOBOSA (JACQ. BENTH (MIMOSACEAE) ON THE SPONTANEOUS CONTRACTILE ACTIVITY OF THE ISOLATED HEART OF RAT
Kassi Yomalan, Semi Anthelme Nene Bi*, Ouga Stanislas Zahoui, Tianga Yaya Soro and Etienne Ehouan Ehilé
Objective: Parkia biglobosa (Mimosaceae) is a plant used in African traditional medicine to treat hypertension and heart disorders. Cardiac activity is underlain by particularly calcium ionic flow through the myocardial membrane. We undertook this study of the effects of an aqueous trunk bark extract of Parkia biglobosa (EAPB) on the isolated heart of rat in modified physiological solutions in order to investigate its influence on the transmembrane transport of the calcium ion which is the main activator of the heart muscle or muscle contraction. Methods: The spontaneous contractile activity of the isolated rat heart is recorded in normal physiological solution and modified physiological solutions with a Langendorff- type device. Results: An aqueous extract of Parkia biglobosa (EAPB), at concentrations between 10-14 and 10-4 mg / ml induces cardiodepressant effects (negative inotropic and chronotropic effects) dose dependent. EAPB inhibits the positive inotropic effect induced by hypercalcic, hyposodic or hypopotassic physiological media that raises the calcium level; which allows to affirm that this substance is a calcium influx inhibitor or a slow calcium channel or voltage-dependent blocker (L-type channels). This characteristic is confirmed by the accentuation of the inhibitory action of EAPB in hypocalcic physiological medium, which reduces the calcium influx, and consequently the concentration of cytosolic calcium. Conclusion: This study shows that EAPB exerts on the isolated heart an anti-calcic effect responsible for its cardiodepressor effects.
Keywords: Parkia biglobosa, isolated rat heart, calcium antagonist effect, cardiodepression.
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