Objectives : This experiments were performed to determine the effect of Linderae Radix extract on norepinephrine-induced arterial contraction in rabbit.
Methods : In order to investigate the effect of Linderae Radix extract on contracted rabbit carotid arterial strips, transverse strips with intact or damaged endothelium were used for the experiment using organ bath. To analyze the mechanism of Linderae Radix extract-induced relaxation, Linderae Radix extract infused into contracted arterial strips induced by norepinephrine after treatment of indomethacin, tetraethylammonium chloride, Nω-nitro-L-arginine or methylene blue.
Results : Linderae Radix extract relax arterial strip with endothelium contracted by norepinephrine, but in the strips without endothelium, Linderae Radix extract-induced relaxation was significantly inhibited.
Linderae Radix extract-induced relaxation was decreased by the pre-treatment of Nω-nitro-L-arginine or methylene blue, but it was not observed in the strips pre-treated with indomethacin or tetraethylammonium chloride.
When Ca^(2+) was applied, the strips which were contracted by norepinephrine in a Ca^(2+)-free solution, arterial contraction was increased. But pre-treatment of Linderae Radix extract inhibited contractile response to norepinephrine and Ca^(2+).
Conclusions : We suggest that Linderae Radix may suppress influx of extra-cellular Ca^(2+) through the formation of nitric oxide, and release of intra-cellular Ca^(2+).
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