• Molecules and Cells
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• 제27권2호
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• pp.191-198
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• 2009

The present study was undertaken to determine whether treatment with genistein, the plant-derived estrogen-like compound influences agonist-induced vascular smooth muscle contraction and, if so, to investigate related mechanisms. The measurement of isometric contractions using a computerized data acquisition system was combined with molecular experiments. Genistein completely inhibited KCl-, phorbol ester-, phenylephrine-, fluoride- and thromboxane $A_2$-induced contractions. An inactive analogue, daidzein, completely inhibited only fluoride-induced contraction regardless of endothelial function, suggesting some difference between the mechanisms of RhoA/Rho-kinase activators such as fluoride and thromboxane $A_2$. Furthermore, genistein and daidzein each significantly decreased phosphorylation of MYPT1 at Thr855 had been induced by a thromboxane $A_2$ mimetic. Interestingly, iberiotoxin, a blocker of large-conductance calcium-activated potassium channels, did not inhibit the relaxation response to genistein or daidzein in denuded aortic rings precontracted with fluoride. In conclusion, genistein or daidzein elicit similar relaxing responses in fluoride-induced contractions, regardless of tyrosine kinase inhibition or endothelial function, and the relaxation caused by genistein or daidzein was not antagonized by large conductance $K_{Ca}$-channel inhibitors in the denuded muscle. This suggests that the RhoA/Rho-kinase pathway rather than $K^+$- channels are involved in the genistein-induced vasodilation. In addition, based on molecular and physiological results, only one vasoconstrictor fluoride seems to be a full RhoA/Rho-kinase activator; the others are partial activators.

• Natural Product Sciences
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• 제16권2호
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• pp.123-132
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• 2010

The aim of the present study was to investigate whether self-fermented pine extract for 2 years (SFPE2) and ethyl acetate (EtOAc) fraction from self-fermented pine needle extract may affect the contractility of the isolated aortic strips and blood pressure of normotensive rats. SFPE2 ($360-1440\;{\mu}g/mL$) significantly depressed both phenylephrine ($10\;{\mu}M$)- and high potassium (56 mM)-induced contractile responses of the isolated rat aortic strips in dose-dependent fashion. The EtOAc-fraction ($400\;{\mu}g/mL$) also inhibited both phenylephrine ($10\;{\mu}M$)- and high potassium (56 mM)-induced contractile responses. Also, in anesthetized normotensive rats, intravenous injection of the EtOAc fraction (1.0~10.0 mg/kg) dose-dependently elicited hypotensive responses. The EtOAc fractions (1.0 and 3.0 mg/kg/30 min) inhibited norepinehrine-induced pressor responses. Intravenous infusion of SFPE2 fraction (3.0 and 10.0 mg/kg/30 min) also inhibited norepinehrine-induced pressor responses in both anesthetized spontaneously hypertensive rats (SHRs) and normotensive rats. In conclusion, these results suggest that both SFPE2 and the EtOAc fraction cause vascular relaxation in the aortic strips isolated from normotensive rats and SHRs as well as vasodepressor responses. Based on these experimental data, it seems that SFPE2 or the EtOAc fraction possesses active antihypertensive components, which are available to prevent or treat hypertension in future.

• Biomolecules & Therapeutics
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• 제7권1호
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• pp.66-78
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• 1999

In order to investigate the pharmacological properties of New Wonbang Woohwangchungsimwon Liquid (NSCL), effects of Wonbang Woohwangchungsimwon Liquid (SCL) and NSCL were compared. In isolated rat aorta, NSCL and SCL showed the relaxation of blood vessels in maximum contractile response to phenylephrine (10$^{-6}$ M) regardless to intact endothelium or denuded rings of the rat aorta. Furthermore, the presences of the inhibitor of NO synthase and guanylate cyclase did not affect the relaxing effect of NSCL and SCL. NSCL and SCL inhibited the vascular contractions induced by acetylcholine, prostaglandin endoperoxide or peroxide in a dose-dependent manner. In conscious spontaneously hypertensive rats (SHRs), NSCL and SCL significantly decreased heart rate. NSCL and SCL, at high doses, had a negative inotropic effect that was a decrease of left ventricular developed pressure and (-dp/dt)/(+dp/dt) in the isolated perfused rat hearts, and also decreased the contractile force and heart rate in the isolated rat right atria. In excised guinea-pig papillary muscle, NSCL and SCL had no effects on parameters of action potential such as resting membrane potential, action potential amplitude, APD$_{90}$ and V$_{max}$ at low doses, whereas inhibited the cardiac contractility at high doses. These results suggested that NSCL and SCL have weak cardiovascular effects with relaxation of blood vessels and decrease of heart rate, and that this effect is no significant differences between cardiovascular effects of two preparations.s.

• Biomolecules & Therapeutics
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• 제4권2호
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• pp.174-183
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• 1996

The general pharmacological properties of Artemisia extract powder (DA-9601) produced from Artemisia asiatica leaves were investigated in mice, rats, guinea pigs and rabbits. DA-9601 at the dose of 800 mg/kg po had no influences on general behaviour, barbital sleeping time and motor coordination of mice. The material at the oral dose of 800 mg/kg did exhibit neither analgesic action nor hypothermic effect. Anticonvulsant action, muscle relaxant action and the effect on intestinal propulsion were not identified at 800 mg/kg po. In the isolated ileum and trachea of guinea pig, the material did not show direct erect and inhibitory action of chemically or electrically stimulated contraction at the concentration of $2\times10^{-5}$g/ml. The sinus rates of atria and contractility of papillary muscle of guinea pig were not influenced by DA-9601 at a dose of $2\times10^{-5}$g/ml. No influences on blood pressure and respiration were observed at 40 mg/kg iv, in rabbits. However, transient decreases in blood pressure of rabbits were observed as given 120 mg/kg in iv route with slight respiratory depression, and slight diuretic effect could be found without any changes in $Na^+$ and $K^+$ excretion.

• Archives of Pharmacal Research
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• 제6권1호
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• pp.69-73
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• 1983

It was reported from our laboratory that the rate of deterioration of the force of contraction was slower in heart from Panax ginseng extract treated rats. Present investigation was designed to elucidate the mechanism of the slow deterioration of contractility of ginseng treated hearts. Therefore, $^{45}Ca^{2+}$ Uptake by sarcoplasmic reticulum (SR) isolated from ginseng treated rate and control rats was studied. Rate weighing 150-250g were administered orally with ginseng ethanol extract (100mg/kg) for 10 days. Cardiac SR was isolated by differential centrifugation and $^{45}Ca^{2+}$ uptake was assessed by the Millipore method. Freshly isolated SR from treated as well as control animals did not show any differences, but after incubation for 30 and 60 min at 37.deg.C, $^{45}Ca^{2+}$ uptake of control animal SR was found to be greatly depressed. The SR of treated animal possessed a greater degree of resistance to incubation. Thus it can be concluded that ginseng may have an ability to sustain the normal function of the heart by sustaining Ca accumulation by SR involved with the excitationcontraction coupling processes.

• Biomolecules & Therapeutics
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• 제31권2호
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• pp.193-199
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• 2023

In this investigation, we made a study of the efficacy of luteolin (a flavonoid found in plants such as vegetables, herbs and fruits) on vascular contractibility and to elucidate the mechanism underlying the relaxation. Isometric contractions of denuded muscles were stored and combined with western blot analysis which was conducted to assess the phosphorylation of myosin phosphatase targeting subunit 1 (MYPT1) and phosphorylation-dependent inhibitory protein for myosin phosphatase (CPI-17) and to examine the effect of luteolin on the RhoA/ROCK/CPI-17 pathway. Luteolin significantly alleviated phorbol ester-, fluoride- and thromboxane mimetic-elicited contractions regardless of endothelial nitric oxide synthesis, implying its direct effect on smooth muscle. It also significantly alleviated the fluoride-elicited elevation in pCPI-17 and pMYPT1 levels and phorbol 12,13-dibutyrate-elicited increase in pERK1/2 level, suggesting depression of ROCK and PKC/MEK activity and ensuing phosphorylation of MYPT1, CPI-17 and ERK1/2. Taken together, these results suggest that luteolin-elicited relaxation includes myosin phosphatase reactivation and calcium desensitization, which seems to be arbitrated by CPI-17 dephosphorylation via ROCK/PKC inhibition.

• Biomolecules & Therapeutics
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• 제30권2호
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• pp.145-150
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• 2022

In this study, we investigated the influence of galangin on vascular contractibility and to determine the mechanism underlying the relaxation. Isometric contractions of denuded aortic muscles were recorded and combined with western blot analysis which was performed to measure the phosphorylation of phosphorylation-dependent inhibitory protein of myosin phosphatase (CPI-17) and myosin phosphatase targeting subunit 1 (MYPT1) and to evaluate the effect of galangin on the RhoA/ROCK/CPI-17 pathway. Galangin significantly inhibited phorbol ester-, fluoride- and thromboxane mimetic-induced vasoconstrictions regardless of endothelial nitric oxide synthesis, suggesting its direct effect on vascular smooth muscle. Galangin significantly inhibited the fluoride-dependent increase in pMYPT1 and pCPI-17 levels and phorbol 12,13-dibutyrate-dependent increase in pERK1/2 level, suggesting repression of ROCK and MEK activity and subsequent phosphorylation of MYPT1, CPI-17 and ERK1/2. Taken together, these results suggest that galangin-induced relaxation involves myosin phosphatase reactivation and calcium desensitization, which appears to be mediated by CPI-17 dephosphorylation via not PKC but ROCK inactivation.

• Biomolecules & Therapeutics
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• 제32권3호
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• pp.361-367
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• 2024

In this study, we investigated the efficacy of kaempferol (a flavonoid found in plants and plant-derived foods such as kale, beans, tea, spinach and broccoli) on vascular contractibility and aimed to clarify the detailed mechanism underlying the relaxation. Isometric contractions of divested muscles were stored and linked with western blot analysis which was carried out to estimate the phosphorylation of myosin phosphatase targeting subunit 1 (MYPT1) and phosphorylation-dependent inhibitory protein for myosin phosphatase (CPI-17) and to estimate the effect of kaempferol on the RhoA/ROCK/CPI-17 pathway. Kaempferol conspicuously impeded phorbol ester-, fluoride- and a thromboxane mimetic-derived contractions regardless of endothelial nitric oxide synthesis, indicating its direct effect on smooth muscles. It also conspicuously impeded the fluoride-derived elevation in phospho-MYPT1 rather than phospho-CPI-17 levels and phorbol 12,13-dibutyrate-derived increase in phospho-CPI-17 and phospho-ERK1/2 levels, suggesting the depression of PKC and MEK activities and subsequent phosphorylation of CPI-17 and ERK1/2. Taken together, these outcomes suggest that kaempferol-derived relaxation incorporates myosin phosphatase retrieval and calcium desensitization, which appear to be modulated by CPI-17 dephosphorylation mainly through PKC inactivation.

• Animal cells and systems
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• 제6권3호
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• pp.253-261
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• 2002

Although cardiac distribution of specific receptors for atrial natriuretic peptide (ANP) was mainly observed in the ventricular endocardium, the modulation of ANP receptors in relation to cardiac development is not defined. The present study was undertaken to investigate ANP receptor modulation in rat during development. In the developmental stages examined (fetus, after postnatal 3-days, 1-, 2-, 3-, 4-, and 8-week-old Sprague Dawley rats) specific ANP binding sites were localized in the right and left ventricular endo-cardia by quantitative in vitro receptor autoradiography using (equation omitted)-rat ANP as labeled ligand. The specific bindings to endocardium were much higher in the right than the left ventricle. The binding affinities of ANP were much higher in the right than the left ventricular endocardium. The difference of these binding affinities among various developmental stages was not observed in the right ventricle, whereas the binding affinity in left ventricle was gradually increased with aging and reached the peak value at 8 weeks. No significant difference in maximal binding capacities of endocardial bindings was observed in the right and left ventricular endocardia during developmental stages. Also, cGMP production via activation of particulate guanylyl cyclase-coupled receptor subtypes in the ventricular membranes was gradually decreased with close relationship to aging. Therefore, the present study show that the endocardial ANP receptor is modulated with close relationship to cardiac development in the left ventricle rather than the right ventricle, and may be involved in regulating myocardial contractility in left heart.

• Molecules and Cells
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• 제20권1호
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• pp.51-56
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• 2005

Excitation-contraction coupling (ECC) proteins in the human heart were characterized using human atrial tissues from different age groups. The samples were classified into one infant group (Group A: 0.2-7 years old) and three adult groups (Group B: 21-30; Group C: 41-49; Group D: 60-66). Whole homogenates (WH) of atrial tissues were assayed for ligand binding, $^{45}Ca^{2+}$ uptake and content of ECC proteins by Western blotting. Equilibrium [$^3H$]ryanodine binding to characterize the ryanodine receptor (RyR) of the sarcoplasmic reticulum (SR) showed that the maximal [$^3H$]ryanodine binding ($B_{max}$) to RyR was similar in all the age groups, but the dissociation constant ($k_d$) of ryanodine was higher in the infant group than the adult groups. Oxalate-supported $^{45}Ca^{2+}$ uptake into the SR, a function of the SR SERCA2a activity, was lower in the infant group than in the adult groups. Similarly, [$^3H$]PN200-110 binding, an index of dihydropyridine receptor (DHPR) density, was lower in the infant group. Expression of calsequestrin and triadin assessed by Western blotting was similar in the infant and adult groups, but junctin expression was considerably higher in the adult groups. These differences in key ECC proteins could underlie the different $Ca^{2+}$ handling properties and contractility of infant hearts.