RT Journal Article SR Electronic T1 Isoflavone Attenuates Vascular Contraction through Inhibition of the RhoA/Rho-Kinase Signaling Pathway JF Journal of Pharmacology and Experimental Therapeutics JO J Pharmacol Exp Ther FD American Society for Pharmacology and Experimental Therapeutics SP 991 OP 998 DO 10.1124/jpet.108.138529 VO 326 IS 3 A1 Young Mi Seok A1 Inji Baek A1 Yong-Hoon Kim A1 Yeon-Shin Jeong A1 In-Jung Lee A1 Dong Hyun Shin A1 Young Hyun Hwang A1 In Kyeom Kim YR 2008 UL http://jpet.aspetjournals.org/content/326/3/991.abstract AB Isoflavones decrease blood pressure, improve lipid profiles, and restore vascular function. We hypothesized that isoflavone attenuates vascular contraction by inhibiting RhoA/Rho-kinase signaling pathway. Rat aortic rings were denuded of endothelium, mounted in organ baths, and contracted with 11,9 epoxymethano-prostaglandin F2α (U46619), a thromboxane A2 analog, or KCl 30 min after the pretreatment with genistein (4′,5,7-trihydroxyisoflavone), daidzein (4′,7-dihydroxyisoflavone), or vehicle. We determined the phosphorylation level of the myosin light chain (MLC20), myosin phosphatase-targeting subunit 1 (MYPT1), and protein kinase C-potentiated inhibitory protein for heterotrimeric myosin light-chain phosphatase of 17 kDa (CPI17) by means of the Western blot. We also measured the amount of GTP RhoA as a marker regarding RhoA activation. The cumulative additions of U46619 or KCl increased vascular tension in a concentration-dependent manner, which were inhibited by pretreatment with genistein or daidzein. Both U46619 (30 nM) and KCl (50 mM) increased MLC20 phosphorylation levels, which were inhibited by genistein and daidzein. Furthermore, both genistein and daidzein decreased the amount of GTP RhoA activated by either U46619 or KCl. U46619 (30 nM) increased phosphorylation of the MYPT1Thr855 and CPI17Thr38, which were also inhibited by genistein or daidzein. However, neither genistein nor daidzein inhibited phorbol 12,13-dibutyrate-induced vascular contraction and CPI17 phosphorylation. In conclusion, isoflavone attenuates vascular contraction, at least in part, through inhibition of the RhoA/Rho-kinase signaling pathway. The American Society for Pharmacology and Experimental Therapeutics