Isoflavone attenuates vascular contraction through inhibition of the RhoA/Rho-kinase signaling pathway.
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 F(2alpha) (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 (MLC(20)), 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 MLC(20) 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 MYPT1(Thr855) and CPI17(Thr38), 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.
Seok
Young Mi
YM
Department of Pharmacology, Kyungpook National University School of Medicine, Daegu 700-422, Republic of Korea.
Baek
Inji
I
Kim
Yong-Hoon
YH
Jeong
Yeon-Shin
YS
Lee
In-Jung
IJ
Shin
Dong Hyun
DH
Hwang
Young Hyun
YH
Kim
In Kyeom
IK
D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D066298:In Vitro Techniques; D007529:Isoflavones / Q000494:pharmacology*; D008297:Male; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology*; D054460:rho-Associated Kinases / Q000037:antagonists & inhibitors* / Q000502:physiology; D020742:rhoA GTP-Binding Protein / Q000037:antagonists & inhibitors* / Q000502:physiology
D007529:Isoflavones; D047428:Protein Kinase Inhibitors; C065753:isoflavanone; D054460:rho-Associated Kinases; D020742:rhoA GTP-Binding Protein