ABSTRACT
<p><b>OBJECTIVE</b>To investigate the effect of bicyclol on vascular oxidative stress injury induced by superoxide anion.</p><p><b>METHODS</b>Rat thoracic aortic rings were isolated for isometric tension recording using organ bath technique. Superoxide arterial injury was induced by pyrogallol exposure, and the effect of bicyclol on endothelium-dependent relaxation was evaluated.</p><p><b>RESULTS</b>Bicyclol (10(-8) - 10(-5) mol/L) relaxed endothelium-intact aortic rings precontracted by phenylephrine. This effect was abolished by L-NAME, an inhibitor of nitric oxide synthase and indomethacin, an inhibitor of cyclooxygenase. Exposure to pyrogallol (500 micromol/L) resulted in decrease of acetylcholine(ACh)-induced endothelium-dependent relaxation in aortic rings, and pre-incubation of bicyclol (10(-5) mol/L) for 45 min improved the relaxation attenuated by pyrogallol. In aortic rings pre-treated with indomethacin, bicyclol increased the ACh-induced relaxation that was inhibited by pyrogallol (500 micromol/L). This effect was not found in aortic rings pre-treated with L-NAME.</p><p><b>CONCLUSION</b>Bicyclol has endothelium-dependent vasodilating effect on rat thoracic aorta and improves vascular function by attenuating oxidative stress. Nitric oxide from endothelium is involved in the anti-oxidative effect of bicyclol.</p>