Journal of North Khorasan

Abstract Background & Objectives: There are some reports on hypotensive and antispasmodic effects of Teucrium polium. The aim of this study was to investigate the vasorelaxant effect of Teucrium polium extract on rat thoracic aorta. Materials & Methods: Sixty four male Wistar rats were divided randomly into 8 groups. The relaxant effects of cumulative concentrations of the extract (1, 2, 4 and 8 mg/ml) on phenylephrine (PE) and potassium chloride (KCl) induced contraction were evaluated in endothelium-intact and -denuded aortas. In another set of experiments the effect of extract (8 mg/ml) on PE and KCl induced contraction in the presence of cumulative calcium concentrations (from 10-5 to 10-2 M) were investigated. Then the effect of the extract on aorta precontracted by PE in the presence of L-NAME (L-NG-Nitroarginine methyl ester, hydrochloride) (100μM) and indomethacin (10μM) were studied. Results: The cumulative concentrations of extract induced a concentration dependent relaxation in the aorta precontracted by PE and KCl. The extract reduced PE and KCl induced contraction in presence of cumulative calcium concentrations. All the extract concentrations (except 1 mg/ml) significantly relaxed PE induced contraction in the presence of L-NAME. The extract significantly relaxed the precontracted aorta by phenylephrine in the presence of indomethacin except by 1 and 2 mg/ml concentrations. Conclusion: The results showed that the extract had vasorelaxant effect on aorta precontracted by PE and KCl. The relaxation mainly was mediated by inhibition calcium influx in vascular smooth muscle cells. It seems the vasorelaxant effect of extract at lower concentrations mediated by nitric oxide and prostacyclin.