• 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.

• Korean Circulation Journal
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• 제53권1호
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• pp.34-46
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• 2023

Background and Objectives: Diabetes mellitus (DM)-associated heart failure (HF) causes high morbidity and mortality. In this study, we established a zebrafish larvae model for in vivo research on diabetic HF. Methods: DM-like phenotypes were induced by treating zebrafish larvae with a combination of D-glucose (GLU) and streptozotocin (STZ). HF was induced by treatment with terfenadine (TER), a potassium channel blocker. Additionally, myocardial contractility, motility, and viability were evaluated. Results: The zebrafish larvae treated with a combination of GLU and STZ showed significantly higher whole-body glucose concentrations, lower insulin levels, and higher phosphoenolpyruvate carboxykinase levels, which are markers of abnormal glucose homeostasis, than the group treated with only GLU, with no effect on viability. When treated with TER, DM zebrafish showed significantly less myocardial fractional shortening and more irregular contractions than the non-DM zebrafish. Furthermore, in DM-HF with reduced ejection fraction (rEF) zebrafish, a significant increase in the levels of natriuretic peptide B, a HF biomarker, markedly reduced motility, and reduced survival rates were observed. Conclusions: We established a DM-HFrEF zebrafish model by sequentially treating zebrafish larvae with GLU, STZ, and TER. Our findings indicate the potential utility of the developed zebrafish larvae model not only in screening studies of new drug candidates for DM-HFrEF but also in mechanistic studies to understand the pathophysiology of DM-HFrEF.

• 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.

• Molecular Medicine Reports
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• 제19권5호
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• pp.3767-3774
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• 2019

The contractility of vascular smooth muscle cells (VSMCs) controls the lumen diameter of vessels, thus serving a role in regulating blood pressure and organ blood flow. Although arginases are known to have numerous effects in the biological activities of VSMCs, the effects of arginase II on the constriction of VSMCs has not yet been investigated. When conducting a natural products screen for an inhibitor against arginase, the present study identified that a relatively high concentration of resveratrol (RSV) exhibited arginase inhibitory activity. Therefore, the present study investigated whether RSV could regulate VSMCs contractions and the underlying mechanism. Arginase inhibition by RSV led to an increase in the concentration of the substrate L-Arg and an accompanying increase in the cytosol Ca2+ concentration [(Ca2+)c] in VSMCs. The increased [Ca2+]c induced by RSV and L-Arg treatments resulted in CaMKII-dependent MLC20 phosphorylation. The effects of RSV on VSMCs were maintained even when VSMCs were pre-treated with sirtinol, an inhibitor of Sirt proteins. In a vascular tension assay with de-endothelialized aortic vessels, vasoconstrictor responses, which were measured using phenylephrine (PE), were significantly enhanced in the RSV- and L-Arg-treated vessels. Therefore, although arginase inhibition has exhibited beneficial effects in various diseases, care is required when considering administration of an arginase inhibitor to patients with vessels endothelial dysfunction as RSV can induce vessel contraction.