FLAVONE INHIBITS VASCULAR CONTRACTION BY DECREASING PHOSPHORYLATION OF THE MYOSIN PHOSPHATASE TARGET SUBUNIT

Jeon, Su Bun,Kim, Gutae,Kim, Jee In,Seok, Young Mi,Kim, Sang-Hyun,Suk, Kyoungho,Shin, Heung-Mook,Lee, Young-Ho,Kim, In Kyeom Wiley-Blackwell Publishing Asia 2007 Clinical and Experimental Pharmacology & Physiolog Vol. No.

<P>SUMMARY</P><OL TYPE='1'><li level='1'>Flavonoids modulate vascular tone through an endothelium-dependent or -independent mechanism. Although a few mechanisms for endothelium-independent relaxation have been suggested, such as interference with protein kinase C or cAMP or cGMP phosphodiesterase, the inhibition of Ca<SUP>2+</SUP> release from intracellular stores or Ca<SUP>2+</SUP> influx from extracellular fluids, the mode of action of flavonoids remains elusive.</LI><li level='1'>We hypothesized that treatment with flavone inhibits vascular smooth muscle contraction by decreasing the phosphorylation of the myosin phosphatase target subunit (MYPT1).</LI><li level='1'>Rat aortic rings were denuded of endothelium, mounted in organ baths and contracted with U46619, a thromboxane A<SUB>2</SUB> analogue.</LI><li level='1'>Flavone dose-dependently inhibited the U46619-induced contractile response and myosin light chain (MLC<SUB>20</SUB>) phosphorylation. At 10<SUP>−7</SUP> mol/L, U46619 induced vascular contraction with the concomitant phosphorylation of MYPT1 at Thr855, but not at Thr697. Incubation with flavone (100 or 300 µmol/L) for 30 min attenuated the phosphorylation of MYPT1<SUB>Thr855</SUB>, but not MYPT1<SUB>Thr697</SUB>.</LI><li level='1'>It is concluded that treatment with flavone inhibits vascular smooth muscle contraction by decreasing the phosphorylation of the MYPT1. These results suggest that flavone causes endothelium-independent relaxation through, at least in part, the inhibition of p160 Rho-associated coiled-coil-containing protein kinase (ROCK) signalling.</LI></OL>

Flavone Attenuates Vascular Contractions by Inhibiting RhoA/Rho Kinase Pathway

Baek, In-Ji,Jeon, Su-Bun,Song, Min-Ji,Yang, Enyue,Sohn, Uy-Dong,Kim, In-Kyeom The Korean Society of Pharmacology 2009 The Korean Journal of Physiology & Pharmacology Vol.13 No.3

Our previous study demonstrated that flavone inhibits vascular contractions by decreasing the phosphorylation levelof the myosin phosphatase target subunit (MYPT1). In the present study, we hypothesized that flavone attenuates vascular contractions through the inhibition of the RhoA/Rho kinase pathway. Rat aortic rings were denuded of endothelium, mounted in organ baths, and contracted with either 30 nM U46619 (a thromboxane A2 analogue) or 8.0 mM NaF 30 min after pretreatment with either flavone (100 or 300 $({\mu}M$) or vehicle. We determined the phosphorylation level of the myosin light chain ($MLC_{20}$), the myosin phophatase targeting subunit 1 (MYPT1) and the protein kinase C-potentiated inhibitory protein for heterotrimeric myosin light chain phophatase of 17-kDa (CPI17) by means of Western blot analysis. Flavone inhibited, not only vascular contractions induced by these contractors, but also the levels of $MLC_{20}$ phosphorylation. Furthermore, flavone inhibited the activation of RhoA which had been induced by either U46619 or NaF. Incubation with flavone attenuated U46619 or NaF-induced phosphorylation of $MYPT1^{Thr855}$ and $CPI17^{Thr38}$, the downstream effectors of Rho-kinase. In regards to the $Ca^{2+}$-free solution, flavone inhibited the phosphorylation of $MYPT1^{Thr855}$ and $CPI17^{Thr38}$, as well as vascular contractions induced by U 46619. These results indicate that flavone attenuates vascular contractions, at least in part, through the inhibition of the RhoA/Rho-kinase pathway.

The Inhibitory Effect of Quercetin on the Agonist-Induced Regulation of Vascular Contractility

( Hyen Oh La ),( Hyun Dong Je ),( Ji Hoon Jeong ) 한국응용약물학회 2011 Biomolecules & Therapeutics(구 응용약물학회지) Vol.19 No.4

The present study was undertaken to investigate the infl uence of quercetin on vascular smooth muscle contractility and to determine the mechanism involved. Denuded aortic rings from male rats were used and isometric contractions were recorded and combined with molecular experiments. Quercetin at a low concentration (0.01-0.03 mM) directly and more signifi cantly relaxed fl uoride or thromboxane A2-induced vascular contraction than phorbol ester-induced contraction suggesting as a possible antihypertensive on the agonist-induced vascular contraction regardless of endothelial nitric oxide synthesis. Furthermore, quercetin more signifi cantly inhibited thromboxane A2-induced increases in pMYPT1 levels than phorbol ester-induced increases. It also more signifi cantly inhibited thromboxane A2-induced increases in pMYPT1 levels than pERK1/2 levels suggesting the mechanism involving the primarily inhibition of Rho-kinase activity and the subsequent phosphorylation of MYPT1. This study provides evidence regarding the mechanism underlying the relaxation effect of quercetin on agonist-induced vascular contraction regardless of endothelial function.

Endothelium Independent Effect of Pelargonidin on Vasoconstriction in Rat Aorta

민영실,윤혁준,제현동,이종혁,유성수,심현섭,이학영,나현오,손의동 한국응용약물학회 2018 Biomolecules & Therapeutics(구 응용약물학회지) Vol.26 No.4

In this study, we investigated the effects of pelargonidin, an anthocyanidin found in many fruits and vegetables, on endotheliumindependent vascular contractility to determine the underlying mechanism of relaxation. Isometric contractions of denuded aortic muscles from male rats were recorded, and the data were combined with those obtained in western blot analysis. Pelargonidin significantly inhibited fluoride-, thromboxane A2-, and phorbol ester-induced vascular contractions, regardless of the presence or absence of endothelium, suggesting a direct effect of the compound on vascular smooth muscles via a different pathway. Pelargonidin significantly inhibited the fluoride-dependent increase in the level of myosin phosphatase target subunit 1 (MYPT1) phosphorylation at Thr-855 and the phorbol 12,13-dibutyrate-dependent increase in the level of extracellular signal-regulated kinase (ERK) 1/2 phosphorylation at Thr202/Tyr204, suggesting the inhibition of Rho-kinase and mitogen-activated protein kinase kinase (MEK) activities and subsequent phosphorylation of MYPT1 and ERK1/2. These results suggest that the relaxation effect of pelargonidin on agonist-dependent vascular contractions includes inhibition of Rho-kinase and MEK activities, independent of the endothelial function.

Hypothermia Inhibits Endothelium-Independent Vascular Contractility via Rho-kinase Inhibition

Chung, Yoon Hee,Oh, Keon Woong,Kim, Sung Tae,Park, Eon Sub,Je, Hyun Dong,Yoon, Hyuk-Jun,Sohn, Uy Dong,Jeong, Ji Hoon,La, Hyen-Oh The Korean Society of Applied Pharmacology 2018 Biomolecules & Therapeutics(구 응용약물학회지) Vol.26 No.2

The present study was undertaken to investigate the influence of hypothermia on endothelium-independent vascular smooth muscle contractility and to determine the mechanism underlying the relaxation. Denuded aortic rings from male rats were used and isometric contractions were recorded and combined with molecular experiments. Hypothermia significantly inhibited fluoride-, thromboxane $A_{2-}$, phenylephrine-, and phorbol ester-induced vascular contractions regardless of endothelial nitric oxide synthesis, suggesting that another pathway had a direct effect on vascular smooth muscle. Hypothermia significantly inhibited the fluoride-induced increase in pMYPT1 level and phorbol ester-induced increase in pERK1/2 level, suggesting inhibition of Rho-kinase and MEK activity and subsequent phosphorylation of MYPT1 and ERK1/2. These results suggest that the relaxing effect of moderate hypothermia on agonist-induced vascular contraction regardless of endothelial function involves inhibition of Rho-kinase and MEK activities.

The Inhibitory Effect of Shikonin on the Agonist-Induced Regulation of Vascular Contractility

( Hyun Dong Je ),( Hyeong Dong Kim ),( Hyen Oh La ) 한국응용약물학회 2015 Biomolecules & Therapeutics(구 응용약물학회지) Vol.23 No.3

Shikonin, a natural flavonoid found in the roots of Lithospermum erythrorhizon, has been shown to possess many biological functions. The present study was undertaken to investigate the influence of shikonin on vascular smooth muscle contractility and to determine the mechanism involved. Denuded aortic rings from male rats were used and isometric contractions were recorded and combined with molecular experiments. Shikonin significantly relaxed fluoride-, thromboxane A2- or phorbol ester-induced vascular contraction suggesting as a possible anti-hypertensive on the agonist-induced vascular contraction regardless of endothelial nitric oxide synthesis. Furthermore, shikonin significantly inhibited fluoride-induced increases in pMYPT1 levels and phorbol esterinduced increases in pERK1/2 levels suggesting the mechanism involving the inhibition of Rho-kinase activity and the subsequent phosphorylation of MYPT1 and the inhibition of MEK activity and the subsequent phosphorylation of ERK1/2. This study provides evidence regarding the mechanism underlying the relaxation effect of shikonin on agonist-induced vascular contraction regardless of endothelial function.

Endothelium-Independent Effect of Fisetin on the Agonist-Induced Regulation of Vascular Contractility

제현동,손의동,나현오 한국응용약물학회 2016 Biomolecules & Therapeutics(구 응용약물학회지) Vol.24 No.1

Fisetin, a natural flavonoid found in a variety of vegetables and fruits, has been shown to possess many biological functions. The present study was undertaken to investigate the influence of fisetin on vascular smooth muscle contractility and to determine the mechanism involved. Denuded aortic rings from male rats were used and isometric contractions were recorded and combined with molecular experiments. Fisetin significantly relaxed fluoride-, thromboxane A2- or phorbol ester-induced vascular contraction suggesting as a possible anti-hypertensive on the agonist-induced vascular contraction regardless of endothelial nitric oxide synthesis. Furthermore, fisetin significantly inhibited fluoride-induced increases in pMYPT1 levels and phorbol ester-induced increases in pERK1/2 levels suggesting the mechanism involving the inhibition of Rho-kinase activity and the subsequent phosphorylation of MYPT1 and MEK activity and the subsequent phosphorylation of ERK1/2. This study provides evidence regarding the mechanism underlying the relaxation effect of fisetin on agonist-induced vascular contraction regardless of endothelial function.

Endothelium-Independent Effect of Fisetin on the Agonist-Induced Regulation of Vascular Contractility

Je, Hyun Dong,Sohn, Uy Dong,La, Hyen-Oh The Korean Society of Applied Pharmacology 2016 Biomolecules & Therapeutics(구 응용약물학회지) Vol.24 No.1

Fisetin, a natural flavonoid found in a variety of vegetables and fruits, has been shown to possess many biological functions. The present study was undertaken to investigate the influence of fisetin on vascular smooth muscle contractility and to determine the mechanism involved. Denuded aortic rings from male rats were used and isometric contractions were recorded and combined with molecular experiments. Fisetin significantly relaxed fluoride-, thromboxane $A_2$- or phorbol ester-induced vascular contraction suggesting as a possible anti-hypertensive on the agonist-induced vascular contraction regardless of endothelial nitric oxide synthesis. Furthermore, fisetin significantly inhibited fluoride-induced increases in pMYPT1 levels and phorbol ester-induced increases in pERK1/2 levels suggesting the mechanism involving the inhibition of Rho-kinase activity and the subsequent phosphorylation of MYPT1 and MEK activity and the subsequent phosphorylation of ERK1/2. This study provides evidence regarding the mechanism underlying the relaxation effect of fisetin on agonist-induced vascular contraction regardless of endothelial function.

Hypothermia Inhibits Endothelium-Independent Vascular Contractility via Rho-kinase Inhibition

정윤희,오건웅,김성태,박언섭,제현동,윤혁준,손의동,정지훈,나현오 한국응용약물학회 2018 Biomolecules & Therapeutics(구 응용약물학회지) Vol.26 No.2

The present study was undertaken to investigate the influence of hypothermia on endothelium-independent vascular smooth muscle contractility and to determine the mechanism underlying the relaxation. Denuded aortic rings from male rats were used and isometric contractions were recorded and combined with molecular experiments. Hypothermia significantly inhibited fluoride-, thromboxane A2-, phenylephrine-, and phorbol ester-induced vascular contractions regardless of endothelial nitric oxide synthesis, suggesting that another pathway had a direct effect on vascular smooth muscle. Hypothermia significantly inhibited the fluorideinduced increase in pMYPT1 level and phorbol ester-induced increase in pERK1/2 level, suggesting inhibition of Rho-kinase and MEK activity and subsequent phosphorylation of MYPT1 and ERK1/2. These results suggest that the relaxing effect of moderate hypothermia on agonist-induced vascular contraction regardless of endothelial function involves inhibition of Rho-kinase and MEK activities.

Endothelium Independent Effect of Pelargonidin on Vasoconstriction in Rat Aorta

Min, Young Sil,Yoon, Hyuk-Jun,Je, Hyun Dong,Lee, Jong Hyuk,Yoo, Seong Su,Shim, Hyun Sub,Lee, Hak Yeong,La, Hyen-Oh,Sohn, Uy Dong The Korean Society of Applied Pharmacology 2018 Biomolecules & Therapeutics(구 응용약물학회지) Vol.26 No.4

In this study, we investigated the effects of pelargonidin, an anthocyanidin found in many fruits and vegetables, on endothelium-independent vascular contractility to determine the underlying mechanism of relaxation. Isometric contractions of denuded aortic muscles from male rats were recorded, and the data were combined with those obtained in western blot analysis. Pelargonidin significantly inhibited fluoride-, thromboxane A2-, and phorbol ester-induced vascular contractions, regardless of the presence or absence of endothelium, suggesting a direct effect of the compound on vascular smooth muscles via a different pathway. Pelargonidin significantly inhibited the fluoride-dependent increase in the level of myosin phosphatase target subunit 1 (MYPT1) phosphorylation at Thr-855 and the phorbol 12,13-dibutyrate-dependent increase in the level of extracellular signal-regulated kinase (ERK) 1/2 phosphorylation at Thr202/Tyr204, suggesting the inhibition of Rho-kinase and mitogen-activated protein kinase kinase (MEK) activities and subsequent phosphorylation of MYPT1 and ERK1/2. These results suggest that the relaxation effect of pelargonidin on agonist-dependent vascular contractions includes inhibition of Rho-kinase and MEK activities, independent of the endothelial function.