Effect of Hydroalcoholic Zizyphus Spina Christi Fruit Extract on The Rate and Contractility of Perfused Frog Heart

The sedative and anxiolytic effects of zizyphus jujube has been reported. Mixed herbal medicine containing jujube is used to treat heart palpitation. The aim of the present study was to investigate the effect of hydroalcohilic zizyphus spina christi fruit extract (from the same Rhamnaceae family) on the rate and contractility of perfused frog heart. The zizyphus spina christi fruit was extracted by percolation method using 70% alchohol. In either sex of pithed frogs (n=19), heart was perfused with Ringer`s solution through vena cava. Percentage changes in cardiac contractility and heart rate were recorded by an isometric transducer after applying final concentrations of 0.625, 1.25, 2.5, 5, 10 and 20 mg/ml of the extract for 1.5-2 min. Cardiac contractility increased in lower concentrations dose dependently (P<0.0001) but it reduced in higher concentrations (P<0.0001). The extract caused cardiac arrest in concentration of 20 mg/ml. It was reversed by washing but not by electrical stimulation. The heart rate also reduced in a dose dependent manner (P<0.0001). The inhibitory effect of high concentration of the extract abolished the positive inotropic effect of epinephrine (P<0.0001). Regarding the constituent`s similarity between Z. jujube and Z. spina christi, it may concluded that jujuboside A or a similar compound binds to calmodulin to inhibit its intracellular functions and consequently decrease excitation and contraction of the frog heart.