Cardiovascular Effect of Capparis spinosa Aqueous Extract. Part VI: in vitro Vasorelaxant Effect

The aim of this study was to investigate the in vitro vasorelaxanteffect of Capparis spinosa aqueous extract (CSAE) at a dose of 10 mg mL^-1. Aortic rings isolated from normal wistar rats were used. The addition of CSAE during the plateau phase of contraction, induced by noradrenaline and KCl, produced a rapid relaxation. Incubation of aortic ring with CSAE during 30 min shifted the noradrenaline induced dose response curve (p<0.001) and the maximum response (p<0.001) was attenuated indicating that antagonist effect of the α1 adrenoreceptors was non-competitive. However, endothelium remove significantly reduced the vasorelaxant effect of CSAE (p<0.01). Furthermore, nitric oxide inhibition reduced the vasorelaxant effect of CSAE. However, cyclo-oxygenase inhibition did not affect the vasorelaxant effect of CSAE (p<0.05). Inhibition of L-type voltage dependent Ca2+ channels did not reduce the observed CSAE vasorelaxant effect (p<0.05). We conclude that CSAE at a dose of 10 mg ml^-1 possess in vitro vasorelaxant effect which may by mediated via an α1 adrenoreceptors antagonism and/or modulation of nitric oxide synthesis.