Aim of the study: Ziziphora clinopodioides Lam. (ZC) is widely used in Uyghur folk medicine for the treatment of hypertension diseases in Xinjiang, an autonomous region of China. To provide pharmacological basis for this traditional use, we explored the vasodilating effects of ZC and investigated the underlying mechanisms. Materials and methods: Activity of hexane (ZCHE), dichloromethane (ZCDE) and aqueous (ZCAE) extracts of ZC were evaluated on isolated rat aortic rings pre-contracted with phenylephrine (PE) or high KCl. The mechanisms were evaluated on ZCDE, the most potent extract. Results: ZCDE-induced relaxation in endothelium-intact aortic rings pre-contracted with phenylephrine (PE, 10(-6) M) or high KCl (6 x 10(-2)M), with respective EC(50) values of 0.27 +/- 0.03 and 0.34 +/- 0.04g/l. Mechanic removal of the endothelium did not significantly modify ZCDE-induced relaxation. In endothelium-denuded aorta pre-contracted with PE (10(-6) M), the vasorelaxant effect of ZCDE was significantly decreased by 4-amino-pyridine (10(-3) M), but not by glibenclamide (10(-4)M), iberiotoxin (3 x 10(-8) M) and thapsigargin (10(-7) M). In Ca(2+) free solution, ZCDE significantly inhibited extracellular Ca(2+)-induced contraction in high KCl and PE pre-contracted rings. Additionally ZDCE inhibited the intracellular Ca(2+) release sensitive to PE (10(-6) M). Conclusions: The results demonstrate that ZDCE exhibits endothelium-independent vasodilating properties that are mediated by inhibition of extracellular Ca(2+) influx through voltage- and receptor-operated Ca2+ channels (VDDCs and ROCCs), by inhibition of Ca(2+) release from intracellular stores, and also by the opening of voltage-dependent K(+) channels. (C) 2010 Elsevier Ireland Ltd. All rights reserved.
UFR Sci Med & Pharmaceut, EA Sci Separat Biol & Pharmaceut 4267, F-25030 Besancon, France;Xinjiang Med Univ, Urumqi, Xinjiang, Peoples R China;Chinese Acad Sci, Xinjiang Key Lab Plant Resources & Nat Prod Chem, Xinjiang Tech Inst Phys & Chem, Urumqi 830011, Peoples R China
Senejoux Francois,Girard Corinne,Kerram Parhat,et al. Mechanisms of vasorelaxation induced by Ziziphora clinopodioides Lam. (Lamiaceae) extract in rat thoracic aorta[J]. JOURNAL OF ETHNOPHARMACOLOGY,2010,132(1):268-273.