Effects of Aqueous Extract of Hibiscus sabdariffa L. (Malvaceae) on the Cardiac Contraction of Rat and Research of the Mechanism of Action

The modification of the ionic concentrations in physiological medium of reference (Mac Ewen), constitutes a model of study of the mechanisms of action for the transmembrane transport of a type of ion. Here, it is the influence of aqueous extract of Hibiscus sabdariffa on the transmembrane transport of the calcium which is required. A series of experiments highlighting calcium ion transport is thus undertaken. Aqueous extract of Hibiscus sabdariffa (AEHS) increases dose-dependently the amplitude of contractile activity of rabbit isolated heart while the frequency decreases concomitantly. Doses ranging from 10-6 mg / ml to 10-1 mg / ml increase the amplitude of the mechanical contractions from 13.5 % to 54.28 % for the respective doses of 10-6 mg / ml and 10-1 mg / ml. The frequency is reduced from 15 % to 57 %. However, reducing the frequency of rhythmic contractions is accentuated with the high concentrations (from 10-1 mg / ml) which induce arrhythmia beginning. In hyposodic medium to which AEHS is added, the contractile force increases from 08 (T1), 24.13 (T2), 43.33 (T3) and to 50 % (T4), the heart rate decreases concomitantly from 11.11 (T1), 25 (T2), 33.33 (T3) and to 50 % (T4). In hypopotassic medium added with AEHS, the contractile force increases by 6.89 (T1), 17.85 (T2), 26.92 (T3) and to 37.5 % (T4) the frequency drops by 14.28 (T2), 33.33 (T3) and to 57.42 % (T4). In hypocalcic medium to which one brings various concentrations of AEHS, the initially reduced contractile force is then raised successively to 06 (T3) and 14.70 % (T4). In hypercalcic medium, the addition of AEHS increases by advantage the contractile force and the frequency. One can thus say that AEHS activates the extracellular calcium entry by an increase in the contractile force while lowering the frequency.