Objectives : This experiments were performed to determine the effect of OYakSoonGi-San extract on hypertension in spontaneous hypertensive rat and norepinephrine-induced arterial contraction in rabbit.
Methods : In order to define the effect of OYakSoonGi-San 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 OYakSoonGi-San extract-induced relaxation, OYakSoonGi-San extract infused into contracted arterial strips induced by norepinephrine after treatment of indomethacin, Nω-nitro-L-arginine, methylene blue or tetraethyla- mmonium chloride.
Results : Blood pressure was significantly decreased five days after administration of OYakSoonGi-San extract.
The relaxation effect of OYakSoonGi-San extract was dependent on the presence of endothelium, showing that OYakSoonGi-San extract-Induced relaxation was not observed in the strips without endothelium.
Also OYakSoonGi-San extract-indeced relaxation was significantly inhibited in arterial strips which were contracted by high K^+.
OYakSoonGi-San extract-indeced relaxation was significantly inhibited 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 additive application of Ca^(2+)in arterial strips which were pre-contracted by norepinephrine in a Ca^(2+)-free solution, arterial contraction was increased. But contractile response to Ca^(2+) was attenuated by pre-treatment of OYakSoonGi-San extract.
Conclusions : These results demonstrated that OYakSoonGi-San could be applied effectively to hypertension and may inhibit agonist-induced contraction through an decrease influx of extra-cellular Ca^(2+) by the formation of nitric oxide in the vascular endothelial cells.
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