The effect of Zizyphus spina-christi leaf extract on the isolated rat aorta.

OBJECTIVE To investigate the effect of Zizyphus spina christi leaf hydroalcoholic extract (ZLHE) on the isolated rat aorta. METHODS The rings of the endothelium intact and denuded thoracic aorta of Male and female Sprague Dawley rats were placed in Krebs-Henseleit solution to measure isometric contractile force. To study the involvement of voltage dependent L type calcium channels, concentration of 10 ?M verapamil was applied. Potassium chloride (50 mM) was also added to the organ bath to compare the effect of extract and KCl. Potassium concentration of the extract at 2.5 and 5 mg/ml was measured. RESULTS ZLHE induced contraction in the endothelium intact and denuded aorta dose dependently and significantly (P < 0.0001). Also, the response to extract at 5 mg/ml was similar to that of KCl (50 mM). The application of verapamil reduced the contraction in the endothelium intact and denuded aorta by 66.7 +/- 3.1% (mean +/- SEM.) and 71.6 +/- 3.8% respectively. CONCLUSION The results showed the vasoconstrictive effect of ZLHE which was not endothelium-dependent and largely blocked by verapamil, suggesting that the voltage-dependent Calcium channels play a pivotal role in the mechanism of action.