<p>Vasodilator effects of Soy Isoflavone Fermentation Products.</p><p>Shingo Yamazaki^1),3),4) Eriko Matsumoto¹⁾ Tatsuki Matsumoto¹⁾ Ayu Ohotsuka¹⁾Hidenori Kanda¹⁾　Hisako Kaneda¹⁾ Noriyasu Sasaki²⁾ Takeharu Kaneda^1),3)</p><p>1) Dept. Veterinary Pharmacol. Nippon Veterinary and Life Science Univ. 2) Dept. Veterinary Biochemistry. Nippon Veterinary and Life Science Univ.3) Dept. Grad. Nippon Veterinary and Life Science Univ. 4) Dept. Aeonpet.Co.LTD.</p><p>It has been reported that isoflavones induced vasorelaxation. However, the effects of hydroxylated isoflavones in vasoconstriction remain unclear. This study investigated the mechanism of vasorelaxation induced by soy IF yeast fermented product (soyF) containing hydroxylated isoflavones in rat aorta. 1) SoyF inhibited KCl and phenylephrine (PE)-induced contraction in a dose-dependent manner. However, these relaxations were not difference between endothelium-intact or -denuted aorta. The inhibitory effect was stronger in PE-induced contraction than that of KCl-induced contraction. 2) Moreover, soyF significantly inhibited U46619-induced contraction and PDBu-induced contraction in Ca-free PSS. 3) Pretreatment with SQ22536, but not ODQ, significantly reduced soyF-evoked inhibition of PE-induced contraction. 4) Forskolin inhibited PE-induced contraction, and pretreatment with soyF significantly enhanced the vasorelaxation of forskolin. 6) SoyF significantly increased cAMP levels. Moreover, higher cAMP levels were obtained with soyF plus forskolin treatment than the total cAMP levels obtained with separate soyF and forskolin treatments. In conclusion, these results suggested that soyF-induced vasorelaxation related to inhibition of contractile element by partly increasing cAMP level via phosphodiesterase inhibition.</p>