Vasorelaxant effect of the aqueous extract of Ajuga iva in rat aorta.

The aim of the present study was to investigate the ex vivo and in vitro vascular activity of the aqueous extract of Ajuga iva (L.) Schreber (Labiatae) in normotensive Wistar rats. Chronic oral administration of the extract of Ajuga iva did not significantly affect the systolic blood pressure. In aorta isolated from Ajuga iva-treated rats, the contractile response to noradrenaline was depressed compared to the responses obtained in aorta from untreated rats but the endothelium-dependent relaxation evoked by acetylcholine was not affected. In vitro, Ajuga iva extract inhibited the contraction evoked by noradrenaline. The addition of Ajuga iva extract during the plateau phase of noradrenaline-evoked contraction produced a relaxation that was sensitive to N-nitro-L-arginine. After pre-incubation of the artery in the presence of the plant extract, vasorelaxant effect was markedly less pronounced. The endothelium-dependent relaxation induced by acetylcholine was concentration-dependently blunted in the presence of Ajuga iva extract in the bathing solution. This study indicates that the aqueous extract of Ajuga iva possesses NO-mediated and NO-independent vasorelaxing properties in vitro while only the endothelium-independent effect was observed ex vivo.