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Pettini F, Spiga O, Furini S, Fusi F. Electrophysiology, molecular modelling, and functional analysis of the effects of dietary quercetin and flavonoid analogues on K ir6.1 channels in rat stomach fundus smooth muscle. Biochem Pharmacol 2024; 220:115969. [PMID: 38086489 DOI: 10.1016/j.bcp.2023.115969] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 12/01/2023] [Accepted: 12/04/2023] [Indexed: 12/17/2023]
Abstract
Flavonoids, ubiquitously distributed in the plant world, are regularly ingested with diets rich in fruit, vegetables, wine, and tea. During digestion, they are partially absorbed in the stomach. The present work aimed to assess the in vitro effects of quercetin and ten structurally related flavonoids on the rat gastric fundus smooth muscle, focussing on ATP-dependent K+ (Kir6.1) channels, which play a central role in the regulation of resting membrane potential, membrane excitability and, consequently, of gastric motility. Whole-cell currents through Kir6.1 channels (IKir6.1) were recorded with the patch-clamp technique and the mechanical activity of gastric fundus smooth muscle strips was studied under isometric conditions. Galangin ≈ tamarixetin > quercetin > kaempferol > isorhamnetin ≈ luteolin ≈ fisetin > (±)-taxifolin inhibited pinacidil-evoked, glibenclamide-sensitive IKir6.1 in a concentration-dependent manner. Morin, rutin, and myricetin were ineffective. The steric hindrance of the molecule and the number and position of hydroxyl groups on the B ring played an important role in the activity of the molecule. Molecular docking simulations revealed a possible binding site for flavonoids in the C-terminal domain of the Kir6.1 channel subunit SUR2B, in a flexible loop formed by residues 251 to 254 of chains C and D. Galangin and tamarixetin, but not rutin relaxed both high K+- and carbachol-induced contraction of fundus strips in a concentration-dependent manner. Furthermore, both flavonoids shifted to the right the concentration-relaxation curves to either pinacidil or L-cysteine constructed in strips pre-contracted by high K+, rutin being ineffective. In conclusion, IKir6.1 inhibition exerted by dietary flavonoids might counterbalance their myorelaxant activity, affect gastric accommodation or, at least, some stages of digestion.
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Affiliation(s)
- Francesco Pettini
- Dipartimento di Biotecnologie, Chimica e Farmacia, Università di Siena, Via A. Moro 2, 53100 Siena, Italy.
| | - Ottavia Spiga
- Dipartimento di Biotecnologie, Chimica e Farmacia, Università di Siena, Via A. Moro 2, 53100 Siena, Italy.
| | - Simone Furini
- Department of Electrical, Electronic and Information Engineering ″Guglielmo Marconi", University of Bologna, via dell'Università 50, 47521, Cesena, (FC), Italy.
| | - Fabio Fusi
- Dipartimento di Biotecnologie, Chimica e Farmacia, Università di Siena, Via A. Moro 2, 53100 Siena, Italy.
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Richter-Laskowska M, Trybek P, Delfino DV, Wawrzkiewicz-Jałowiecka A. Flavonoids as Modulators of Potassium Channels. Int J Mol Sci 2023; 24:1311. [PMID: 36674825 PMCID: PMC9861088 DOI: 10.3390/ijms24021311] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 01/02/2023] [Accepted: 01/04/2023] [Indexed: 01/12/2023] Open
Abstract
Potassium channels are widely distributed integral proteins responsible for the effective and selective transport of K+ ions through the biological membranes. According to the existing structural and mechanistic differences, they are divided into several groups. All of them are considered important molecular drug targets due to their physiological roles, including the regulation of membrane potential or cell signaling. One of the recent trends in molecular pharmacology is the evaluation of the therapeutic potential of natural compounds and their derivatives, which can exhibit high specificity and effectiveness. Among the pharmaceuticals of plant origin, which are potassium channel modulators, flavonoids appear as a powerful group of biologically active substances. It is caused by their well-documented anti-oxidative, anti-inflammatory, anti-mutagenic, anti-carcinogenic, and antidiabetic effects on human health. Here, we focus on presenting the current state of knowledge about the possibilities of modulation of particular types of potassium channels by different flavonoids. Additionally, the biological meaning of the flavonoid-mediated changes in the activity of K+ channels will be outlined. Finally, novel promising directions for further research in this area will be proposed.
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Affiliation(s)
- Monika Richter-Laskowska
- The Centre for Biomedical Engineering, Łukasiewicz Research Network—Krakow Institute of Technology, 30-418 Krakow, Poland
| | - Paulina Trybek
- Faculty of Science and Technology, University of Silesia in Katowice, 41-500 Chorzów, Poland
| | | | - Agata Wawrzkiewicz-Jałowiecka
- Department of Physical Chemistry and Technology of Polymers, Silesian University of Technology, 44-100 Gliwice, Poland
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Lipofundin MCT/LCT Inhibits Levcromakalim-Induced Vasodilation by Inhibiting Endothelial Nitric Oxide Release. Int J Mol Sci 2020; 21:ijms21051763. [PMID: 32143531 PMCID: PMC7084418 DOI: 10.3390/ijms21051763] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2020] [Revised: 02/29/2020] [Accepted: 03/02/2020] [Indexed: 11/17/2022] Open
Abstract
The goal of this study was to examine the effect of lipid emulsion on the vasodilation induced by ATP-sensitive potassium (KATP) channels in isolated rat aortae and the underlying mechanism. The effects of Intralipid, containing 100% long-chain fatty acids, and Lipofundin MCT/LCT, containing 50% long-chain fatty acids plus 50% medium-chain fatty acids, on the vasodilation induced by levcromakalim in endothelium-intact aorta with or without NW-nitro-L-arginine methyl ester (L-NAME) and in endothelium-denuded aorta were examined. The effects of L-arginine, L-NAME, glibenclamide, and Lipofundin MCT/LCT, alone or combined, on the levcromakalim-induced vasodilation were examined. Lipofundin MCT/LCT inhibited the levcromakalim-induced vasodilation of isolated endothelium-intact aortae, whereas Intralipid did not. In addition, Lipofundin MCT/LCT had no effect on the levcromakalim-induced vasodilation of endothelium-denuded rat aortae and endothelium-intact aortae with L-NAME. L-arginine and Lipofundin MCT/LCT produced more levcromakalim-induced vasodilation than Lipofundin MCT/LCT alone. Glibenclamide inhibited levcromakalim-induced vasodilation. Levcromakalim did not significantly alter endothelial nitric oxide synthase phosphorylation, whereas Lipofundin MCT/LCT decreased cyclic guanosine monophosphate. Lipofundin MCT/LCT did not significantly alter levcromakalim-induced membrane hyperpolarization. Taken together, these results suggest that Lipofundin MCT/LCT inhibits the vasodilation induced by levcromakalim by inhibiting basally released endothelial nitric oxide, which seems to occur through medium-chain fatty acids.
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Fusi F, Trezza A, Tramaglino M, Sgaragli G, Saponara S, Spiga O. The beneficial health effects of flavonoids on the cardiovascular system: Focus on K+ channels. Pharmacol Res 2020; 152:104625. [DOI: 10.1016/j.phrs.2019.104625] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Revised: 12/14/2019] [Accepted: 12/31/2019] [Indexed: 01/17/2023]
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Lee SH, Kang D, Ok SH, Kwon SC, Kim HJ, Kim EJ, Hong JM, Kim JY, Bae SI, An S, Sohn JT. Linoleic Acid Attenuates the Toxic Dose of Bupivacaine-Mediated Reduction of Vasodilation Evoked by the Activation of Adenosine Triphosphate-Sensitive Potassium Channels. Int J Mol Sci 2018; 19:ijms19071876. [PMID: 29949899 PMCID: PMC6073907 DOI: 10.3390/ijms19071876] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Revised: 06/19/2018] [Accepted: 06/22/2018] [Indexed: 01/20/2023] Open
Abstract
The goal of this study was to investigate the effect of lipid emulsion on a toxic dose of local anesthetic-mediated reduction of vasodilation evoked by the ATP-sensitive potassium (KATP) channel agonist levcromakalim. The effect of lipid emulsion (LE) and linoleic acid on the local anesthetic-mediated reduction of vasodilation and membrane hyperpolarization evoked by levcromakalim was assessed in isolated endothelium-denuded vessels (rat aorta and mesenteric artery) and aortic vascular smooth muscle cells. The effect of LE and linoleic acid on KATP channel activity in transfected HEK-293 cells was investigated, as was the effect of LE on bupivacaine concentration. The efficacy of LE in attenuating the local anesthetic-mediated reduction of vasodilation evoked by levcromakalim was correlated with the lipid solubility of the local anesthetic. Linoleic acid attenuated the bupivacaine-mediated reduction of vasodilation evoked by levcromakalim. LE decreased the bupivacaine-mediated reduction of membrane hyperpolarization evoked by levcromakalim but did not significantly alter the mepivacaine-mediated reduction. LE and linoleic acid both reversed the bupivacaine-mediated decrease of KATP activity and enhanced KATP activity. LE decreased the bupivacaine concentration. Linoleic acid may be the major contributor to LE-induced attenuation of bupivacaine-mediated reduction of vasodilation evoked by levcromakalim via the direct activation of KATP channels and indirect effects.
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Affiliation(s)
- Soo Hee Lee
- Department of Anesthesiology and Pain Medicine, Gyeongsang National University School of Medicine, Gyeongsang National University Hospital, 15 Jinju-daero 816 beon-gil, Jinju-si 52727, Republic of Korea.
- Institute of Health Sciences, Gyeongsang National University, Jinju-si 52727, Republic of Korea.
| | - Dawon Kang
- Department of Physiology, Gyeongsang National University School of Medicine, Jinju-si 52727, Republic of Korea.
| | - Seong-Ho Ok
- Department of Anesthesiology and Pain Medicine, Gyeongsang National University School of Medicine, Gyeongsang National University Hospital, 15 Jinju-daero 816 beon-gil, Jinju-si 52727, Republic of Korea.
- Institute of Health Sciences, Gyeongsang National University, Jinju-si 52727, Republic of Korea.
| | - Seong-Chun Kwon
- Department of Physiology, Institute of Clinical and Translational Research, Catholic Kwangdong University, College of Medicine, Gangneung 25601, Republic of Korea.
| | - Hyun-Jin Kim
- Division of Applied Life Sciences (BK21 plus), Gyeongsang National University, 501 Jinju-daero, Jinju 52828, Republic of Korea.
- Department of Food Science & Technology, and Institute of Agriculture and Life Science, Gyeongsang National University, 501 Jinju-daero, Jinju 52828, Republic of Korea.
| | - Eun-Jin Kim
- Department of Physiology, Gyeongsang National University School of Medicine, Jinju-si 52727, Republic of Korea.
| | - Jeong-Min Hong
- Department of Anesthesia and Pain Medicine, Pusan National University Hospital, Biomed Research Institute, Pusan National University School of Medicine, Busan 49241, Republic of Korea.
| | - Ji-Yoon Kim
- Department of Anesthesiology and Pain Medicine, Gyeongsang National University Hospital, 15 Jinju-daero 816 beon-gil, Jinju-si 52727, Republic of Korea.
| | - Sung Il Bae
- Department of Anesthesiology and Pain Medicine, Gyeongsang National University Hospital, 15 Jinju-daero 816 beon-gil, Jinju-si 52727, Republic of Korea.
| | - Seungmin An
- Department of Anesthesiology and Pain Medicine, Gyeongsang National University Hospital, 15 Jinju-daero 816 beon-gil, Jinju-si 52727, Republic of Korea.
| | - Ju-Tae Sohn
- Department of Anesthesiology and Pain Medicine, Gyeongsang National University School of Medicine, Gyeongsang National University Hospital, 15 Jinju-daero 816 beon-gil, Jinju-si 52727, Republic of Korea.
- Institute of Health Sciences, Gyeongsang National University, Jinju-si 52727, Republic of Korea.
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Trezza A, Cicaloni V, Porciatti P, Langella A, Fusi F, Saponara S, Spiga O. From in silico to in vitro: a trip to reveal flavonoid binding on the Rattus norvegicus Kir6.1 ATP-sensitive inward rectifier potassium channel. PeerJ 2018; 6:e4680. [PMID: 29736333 PMCID: PMC5936070 DOI: 10.7717/peerj.4680] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Accepted: 04/09/2018] [Indexed: 12/18/2022] Open
Abstract
Background ATP-sensitive inward rectifier potassium channels (Kir), are a potassium channel family involved in many physiological processes. KATP dysfunctions are observed in several diseases such as hypoglycaemia, hyperinsulinemia, Prinzmetal angina–like symptoms, cardiovascular diseases. Methods A broader view of the KATP mechanism is needed in order to operate on their regulation, and in this work we clarify the structure of the Rattus norvegicus ATP-sensitive inward rectifier potassium channel 8 (Kir6.1), which has been obtained through a homology modelling procedure. Due to the medical use of flavonoids, a considerable increase in studies on their influence on human health has recently been observed, therefore our aim is to study, through computational methods, the three-dimensional (3D) conformation together with mechanism of action of Kir6.1 with three flavonoids. Results Computational analysis by performing molecular dynamics (MD) and docking simulation on rat 3D modelled structure have been completed, in its closed and open conformation state and in complex with Quercetin, 5-Hydroxyflavone and Rutin flavonoids. Our study showed that only Quercetin and 5-Hydroxyflavone were responsible for a significant down-regulation of the Kir6.1 activity, stabilising it in a closed conformation. This hypothesis was supported by in vitro experiments demonstrating that Quercetin and 5-Hydroxyflavone were capable to inhibit KATP currents of rat tail main artery myocytes recorded by the patch-clamp technique. Conclusion Combined methodological approaches, such as molecular modelling, docking and MD simulations of Kir6.1 channel, used to elucidate flavonoids intrinsic mechanism of action, are introduced, revealing a new potential druggable protein site.
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Affiliation(s)
- Alfonso Trezza
- Department of Biotechnology, Chemistry and Pharmacy, University of Siena, Siena, Italy
| | - Vittoria Cicaloni
- Department of Biotechnology, Chemistry and Pharmacy, University of Siena, Siena, Italy.,Toscana Life Sciences Foundation, Siena, Italy
| | - Piera Porciatti
- Department of Biotechnology, Chemistry and Pharmacy, University of Siena, Siena, Italy
| | - Andrea Langella
- Department of Biotechnology, Chemistry and Pharmacy, University of Siena, Siena, Italy
| | - Fabio Fusi
- Department of Life Sciences, University of Siena, Siena, Italy
| | - Simona Saponara
- Department of Life Sciences, University of Siena, Siena, Italy
| | - Ottavia Spiga
- Department of Biotechnology, Chemistry and Pharmacy, University of Siena, Siena, Italy
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Real J, Miranda C, Olofsson CS, Smith PA. Lipophilicity predicts the ability of nonsulphonylurea drugs to block pancreatic beta-cell K ATP channels and stimulate insulin secretion; statins as a test case. Endocrinol Diabetes Metab 2018; 1:e00017. [PMID: 30815553 PMCID: PMC6354820 DOI: 10.1002/edm2.17] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Revised: 01/18/2018] [Accepted: 02/18/2018] [Indexed: 12/26/2022] Open
Abstract
AIMS KATP ion channels play a key role in glucose-stimulated insulin secretion. However, many drugs block KATP as "off targets" leading to hyperinsulinaemia and hypoglycaemia. As such drugs are often lipophilic, the aim was to examine the relationship between drug lipophilicity (P) and IC 50 for KATP block and explore if the IC 50's of statins could be predicted from their lipophilicity and whether this would allow one to forecast their acute action on insulin secretion. MATERIALS AND METHODS A meta-analysis of 26 lipophilic, nonsulphonylurea, blockers of KATP was performed. From this, the IC 50's for pravastatin and simvastatin were predicted and then tested experimentally by exploring their effects on KATP channel activity via patch-clamp measurement, calcium imaging and insulin secretion in murine beta cells and islets. RESULTS Nonsulphonylurea drugs inhibited KATP channels with a Log IC 50 linearly related to their logP. Simvastatin blocked KATP with an IC 50 of 25 nmol/L, a value independent of cytosolic factors, and within the range predicted by its lipophilicity (21-690 nmol/L). 10 μmol/L pravastatin, predicted IC 50 0.2-12 mmol/L, was without effect on the KATP channel. At 10-fold therapeutic levels, 100 nmol/L simvastatin depolarized the beta-cell membrane potential and stimulated Ca2+ influx but did not affect insulin secretion; the latter could be explained by serum binding. CONCLUSIONS The logP of a drug can aid prediction for its ability to block beta-cell KATP ion channels. However, although the IC 50 for the block of KATP by simvastatin was predicted, the difference between this and therapeutic levels, as well as serum sequestration, explains why hypoglycaemia is unlikely to be observed with acute use of this statin.
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Affiliation(s)
- Joana Real
- Department of Physiology/Metabolic PhysiologyInstitute of Neuroscience and PhysiologyGöteborgSweden
| | - Caroline Miranda
- Department of Physiology/Metabolic PhysiologyInstitute of Neuroscience and PhysiologyGöteborgSweden
| | - Charlotta S. Olofsson
- Department of Physiology/Metabolic PhysiologyInstitute of Neuroscience and PhysiologyGöteborgSweden
| | - Paul A. Smith
- School of Life Sciences University of NottinghamNottinghamUK
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Fusi F, Spiga O, Trezza A, Sgaragli G, Saponara S. The surge of flavonoids as novel, fine regulators of cardiovascular Ca v channels. Eur J Pharmacol 2016; 796:158-174. [PMID: 28012974 DOI: 10.1016/j.ejphar.2016.12.033] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Revised: 12/15/2016] [Accepted: 12/20/2016] [Indexed: 01/28/2023]
Abstract
Ion channels underlie a wide variety of physiological processes that involve rapid changes in cell dynamics, such as cardiac and vascular smooth muscle contraction. Overexpression or dysfunction of these membrane proteins are the basis of many cardiovascular diseases that represent the leading cause of morbidity and mortality for human beings. In the last few years, flavonoids, widely distributed in the plant kingdom, have attracted the interest of many laboratories as an emerging class of fine ion, in particular Cav, channels modulators. Pieces of in vitro evidence for direct as well as indirect effects exerted by various flavonoids on ion channel currents are now accumulating in the scientific literature. This activity may be responsible, at least in part, for the beneficial and protective effects of dietary flavonoids toward cardiovascular diseases highlighted in several epidemiological studies. Here we examine numerous studies aimed at analysing this feature of flavonoids, focusing on the mechanisms that promote their sometimes controversial activities at cardiovascular Cav channels. New methodological approaches, such as molecular modelling and docking to Cav1.2 channel α1c subunit, used to elucidate flavonoids intrinsic mechanism of action, are introduced. Moreover, flavonoid-membrane interaction, bioavailability, and antioxidant activity are taken into account and discussed.
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Affiliation(s)
- Fabio Fusi
- Dipartimento di Scienze della Vita, Università degli Studi di Siena, via A. Moro 2, 53100 Siena, Italy.
| | - Ottavia Spiga
- Dipartimento di Biotecnologie, Chimica e Farmacia, Università degli Studi di Siena, via A. Moro 2, 53100 Siena, Italy
| | - Alfonso Trezza
- Dipartimento di Biotecnologie, Chimica e Farmacia, Università degli Studi di Siena, via A. Moro 2, 53100 Siena, Italy
| | - Giampietro Sgaragli
- Dipartimento di Scienze della Vita, Università degli Studi di Siena, via A. Moro 2, 53100 Siena, Italy
| | - Simona Saponara
- Dipartimento di Scienze della Vita, Università degli Studi di Siena, via A. Moro 2, 53100 Siena, Italy
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Baik J, Ok SH, Kim EJ, Kang D, Hong JM, Shin IW, Lee HK, Chung YK, Cho Y, Lee SH, Kang S, Sohn JT. Mepivacaine attenuates vasodilation induced by ATP-sensitive potassium channels in rat aorta. Can J Physiol Pharmacol 2016; 94:1211-1219. [PMID: 27636507 DOI: 10.1139/cjpp-2016-0041] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The goal of this in vitro study was to investigate the effect of mepivacaine on vasodilation induced by the ATP-sensitive potassium (KATP) channel opener levcromakalim in isolated endothelium-denuded rat aortas. The effects of mepivacaine and the KATP channel inhibitor glibenclamide, alone or in combination, on levcromakalim-induced vasodilation were assessed in the isolated aortas. The effects of mepivacaine or combined treatment with a protein kinase C (PKC) inhibitor, GF109203X, and mepivacaine on this vasodilation were also investigated. Levcromakalim concentration-response curves were generated for isolated aortas precontracted with phenylephrine or a PKC activator, phorbol 12,13-dibutyrate (PDBu). Further, the effects of mepivacaine and glibenclamide on levcromakalim-induced hyperpolarization were assessed in rat aortic vascular smooth muscle cells. Mepivacaine attenuated levcromakalim-induced vasodilation, whereas it had no effect on this vasodilation in isolated aortas pretreated with glibenclamide. Combined treatment with GF109203X and mepivacaine enhanced levcromakalim-induced vasodilation compared with pretreatment with mepivacaine alone. This vasodilation was attenuated in aortas precontracted with PDBu compared with those precontracted with phenylephrine. Mepivacaine and glibenclamide, alone or in combination, attenuated levcromakalim-induced membrane hyperpolarization. Taken together, these results suggest that mepivacaine attenuates vasodilation induced by KATP channels, which appears to be partly mediated by PKC.
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Affiliation(s)
- Jiseok Baik
- a Department of Anesthesia and Pain Medicine, School of Medicine, Pusan National University, Biomedical Research Institute, Pusan National University Hospital, 179 Gudeok-ro, Seo-gu, Busan-si, 602-739, Republic of Korea
| | - Seong-Ho Ok
- b Department of Anesthesiology and Pain Medicine, Gyeongsang National University School of Medicine and Gyeongsang National University Hospital, Jinju-si, 52727, Republic of Korea
| | - Eun-Jin Kim
- c Department of Physiology, Gyeongsang National University School of Medicine, Jinju-si, 52727, Republic of Korea
| | - Dawon Kang
- c Department of Physiology, Gyeongsang National University School of Medicine, Jinju-si, 52727, Republic of Korea
| | - Jeong-Min Hong
- a Department of Anesthesia and Pain Medicine, School of Medicine, Pusan National University, Biomedical Research Institute, Pusan National University Hospital, 179 Gudeok-ro, Seo-gu, Busan-si, 602-739, Republic of Korea
| | - Il-Woo Shin
- b Department of Anesthesiology and Pain Medicine, Gyeongsang National University School of Medicine and Gyeongsang National University Hospital, Jinju-si, 52727, Republic of Korea
| | - Heon Keun Lee
- b Department of Anesthesiology and Pain Medicine, Gyeongsang National University School of Medicine and Gyeongsang National University Hospital, Jinju-si, 52727, Republic of Korea
| | - Young-Kyun Chung
- b Department of Anesthesiology and Pain Medicine, Gyeongsang National University School of Medicine and Gyeongsang National University Hospital, Jinju-si, 52727, Republic of Korea
| | - Youngil Cho
- d Department of Anesthesiology and Pain Medicine, Gyeongsang National University Hospital, Jinju-si, 52727, Republic of Korea
| | - Soo Hee Lee
- d Department of Anesthesiology and Pain Medicine, Gyeongsang National University Hospital, Jinju-si, 52727, Republic of Korea
| | - Sebin Kang
- d Department of Anesthesiology and Pain Medicine, Gyeongsang National University Hospital, Jinju-si, 52727, Republic of Korea
| | - Ju-Tae Sohn
- b Department of Anesthesiology and Pain Medicine, Gyeongsang National University School of Medicine and Gyeongsang National University Hospital, Jinju-si, 52727, Republic of Korea.,e Institute of Health Sciences, Gyeongsang National University, Jinju, Republic of Korea
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10
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Kow LM, Pfaff DW. Rapid estrogen actions on ion channels: A survey in search for mechanisms. Steroids 2016; 111:46-53. [PMID: 26939826 PMCID: PMC4929851 DOI: 10.1016/j.steroids.2016.02.018] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2016] [Revised: 02/22/2016] [Accepted: 02/25/2016] [Indexed: 12/31/2022]
Abstract
A survey of nearly two hundred reports shows that rapid estrogenic actions can be detected across a range of kinds of estrogens, a range of doses, on a wide range of tissue, cell and ion channel types. Striking is the fact that preparations of estrogenic agents that do not permeate the cell membrane almost always mimic the actions of the estrogenic agents that do permeate the membrane. All kinds of estrogens, ranging from natural ones, through receptor modulators, endocrine disruptors, phytoestrogens, agonists, and antagonists to novel G-1 and STX, have been reported to be effective. For actions on specific types of ion channels, the possibility of opposing actions, in different cases, is the rule, not the exception. With this variety there is no single, specific action mechanism for estrogens per se, although in some cases estrogens can act directly or via some signaling pathways to affect ion channels. We infer that estrogens can bind a large number of substrates/receptors at the membrane surface. As against the variety of subsequent routes of action, this initial step of the estrogen's binding action is the key.
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Affiliation(s)
- Lee-Ming Kow
- The Rockefeller University, New York, NY 10065, USA.
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11
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Gencel VB, Benjamin MM, Bahou SN, Khalil RA. Vascular effects of phytoestrogens and alternative menopausal hormone therapy in cardiovascular disease. Mini Rev Med Chem 2012; 12:149-74. [PMID: 22070687 DOI: 10.2174/138955712798995020] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2011] [Revised: 07/27/2011] [Accepted: 08/05/2011] [Indexed: 01/10/2023]
Abstract
Phytoestrogens are estrogenic compounds of plant origin classified into different groups including isoflavones, lignans, coumestans and stilbenes. Isoflavones such as genistein and daidzein are the most studied and most potent phytoestrogens, and are found mainly in soy based foods. The effects of phytoestrogens are partly mediated via estrogen receptors (ERs): ERα, ERβ and possibly GPER. The interaction of phytoestrogens with ERs is thought to induce both genomic and non-genomic effects in many tissues including the vasculature. Some phytoestrogens such as genistein have additional non-ER-mediated effects involving signaling pathways such as tyrosine kinase. Experimental studies have shown beneficial effects of phytoestrogens on endothelial cells, vascular smooth muscle, and extracellular matrix. Phytoestrogens may also affect other pathophysiologic vascular processes such as lipid profile, angiogenesis, inflammation, tissue damage by reactive oxygen species, and these effects could delay the progression of atherosclerosis. As recent clinical trials showed no vascular benefits or even increased risk of cardiovascular disease (CVD) and CV events with conventional menopausal hormone therapy (MHT), phytoestrogens are being considered as alternatives to pharmacologic MHT. Epidemiological studies in the Far East population suggest that dietary intake of phytoestrogens may contribute to the decreased incidence of postmenopausal CVD and thromboembolic events. Also, the WHO-CARDIAC study supported that consumption of high soybean diet is associated with lower mortalities from coronary artery disease. However, as with estrogen, there has been some discrepancy between the experimental studies demonstrating the vascular benefits of phytoestrogens and the data from clinical trials. This is likely because the phytoestrogens clinical trials have been limited in many aspects including the number of participants enrolled, the clinical end points investigated, and the lack of long-term follow-up. Further investigation of the cellular mechanisms underlying the vascular effects of phytoestrogens and careful evaluation of the epidemiological evidence and clinical trials of their potential vascular benefits would put forward the use of phytoestrogens as an alternative MHT for the relief of menopausal symptoms and amelioration of postmenopausal CVD.
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Affiliation(s)
- V B Gencel
- Vascular Surgery Research Laboratory, Division of Vascular and Endovascular Surgery, Brigham and Women's Hospital, and Harvard Medical School, Boston, MA 02115, USA
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12
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Scholz EP, Zitron E, Katus HA, Karle CA. Cardiovascular ion channels as a molecular target of flavonoids. Cardiovasc Ther 2010; 28:e46-52. [PMID: 20633021 DOI: 10.1111/j.1755-5922.2010.00212.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Flavonoids are a class of naturally occurring polyphenols abundant in edibles and beverages of plant origin. Epidemiological studies consistently associate high flavonoid intake with a reduced risk for the development of cardiovascular diseases. So far these beneficial effects have been mainly attributed to nonspecific antioxidant and antiinflammatory properties. However, there is an increasing body of evidence that flavonoids specifically target molecular structures including cardiovascular ion channels. Playing a pivotal role in the regulation of vascular tone and cardiac electric activity, ion channels represent a major target for the induction of antihypertensive and cardioprotective effects. Thus, pharmacological properties of flavonoids on cardiovascular ion channels, ion currents and tissue preparations are being increasingly addressed in experimental studies. Whereas it has become clear that cardiovascular ion channels represent an important molecular target of flavonoids, the published data have not yet been systematically reviewed.
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Affiliation(s)
- Eberhard P Scholz
- Department of Internal Medicine III (Cardiology), University Hospital Heidelberg, Heidelberg, Germany.
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13
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Wong CO, Huang Y, Yao X. Genistein potentiates activity of the cation channel TRPC5 independently of tyrosine kinases. Br J Pharmacol 2010; 159:1486-96. [PMID: 20233211 DOI: 10.1111/j.1476-5381.2010.00636.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND AND PURPOSE TRPC5 is a Ca(2+)-permeable channel with multiple modes of activation. We have explored the effects of genistein, a plant-derived isoflavone, on TRPC5 activity, and the mechanism(s) involved. EXPERIMENTAL APPROACH Effects of genistein on TRPC5 channels were investigated in TRPC5-over-expressing human embryonic kidney 293 (HEK) cells and bovine aortic endothelial cells (BAECs) using fluorescent Ca(2+) imaging and electrophysiological techniques. KEY RESULTS In TRPC5-over-expressing HEK cells, genistein stimulated TRPC5-mediated Ca(2+) influx, concentration dependently (EC(50)= 93 microM). Genistein and lanthanum activated TRPC5 channels synergistically. Effects of genistein on TRPC5 channels were mimicked by daidzein (100 microM), a genistein analogue inactive as a tyrosine kinase inhibitor, but not by known tyrosine kinase inhibitors herbimycin (2 microM), PP2 (20 microM) and lavendustin A (10 microM). Action of genistein on TRPC5 channels was not affected by an oestrogen receptor inhibitor ICI-182780 (50 microM) or a phospholipase C inhibitor U73122 (10 microM), suggesting genistein did not act through oestrogen receptors or phospholipase C. In BAECs, genistein (100 microM) stimulated TRPC5-mediated Ca(2+) influx. In patch clamp studies, both genistein (50 microM) and daidzein (50 microM) augmented TRPC5-mediated whole-cell cation current in TRPC5 over-expressing HEK cells. Genistein stimulated TRPC5 channel activity in excised inside-out membrane patch, suggesting that its action was relatively direct and did not require cytosolic factors. CONCLUSIONS AND IMPLICATIONS The present study is the first to demonstrate stimulation of a TRP channel by isoflavones. Genistein is a lipophilic compound able to stimulate TRPC5 activity in TRPC5-over-expressing HEK cells and in native vascular endothelial cells.
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Affiliation(s)
- Ching-On Wong
- Li Ka Shing Institute of Health Sciences and School of Biomedical Sciences, Faculty of Medicine, Chinese University of Hong Kong, Hong Kong, China
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14
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Regulation of two-pore-domain (K2P) potassium leak channels by the tyrosine kinase inhibitor genistein. Br J Pharmacol 2008; 154:1680-90. [PMID: 18516069 DOI: 10.1038/bjp.2008.213] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND AND PURPOSE Two-pore-domain potassium (K2P) channels mediate potassium background (or 'leak') currents, controlling excitability by stabilizing membrane potential below firing threshold and expediting repolarization. Inhibition of K2P currents permits membrane potential depolarization and excitation. As expected for key regulators of excitability, leak channels are under tight control from a plethora of stimuli. Recently, signalling via protein tyrosine kinases (TKs) has been implicated in ion channel modulation. The objective of this study was to investigate TK regulation of K2P channels. EXPERIMENTAL APPROACH The two-electrode voltage clamp technique was used to record K2P currents in Xenopus oocytes. In addition, K2P channels were studied in Chinese hamster ovary (CHO) cells using the whole-cell patch clamp technique. KEY RESULTS Here, we report inhibition of human K2P3.1 (TASK-1) currents by the TK antagonist, genistein, in Xenopus oocytes (IC50=10.7 microM) and in CHO cells (IC50=12.3 microM). The underlying molecular mechanism was studied in detail. hK2P3.1 was not affected by genistin, an inactive analogue of genistein. Perorthovanadate, an inhibitor of tyrosine phosphatase activity, reduced the inhibitory effect of genistein. Current reduction was voltage independent and did not require channel protonation at position H98 or phosphorylation at the single TK phosphorylation site, Y323. Among functional hK2P family members, genistein also reduced K2P6.1 (TWIK-2), K2P9.1 (TASK-3) and K2P13.1 (THIK-1) currents, respectively. CONCLUSIONS AND IMPLICATIONS Modulation of K2P channels by the TK inhibitor, genistein, represents a novel molecular mechanism to alter background K+ currents.
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15
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Genistein inhibits voltage-gated sodium currents in SCG neurons through protein tyrosine kinase-dependent and kinase-independent mechanisms. Pflugers Arch 2008; 456:857-66. [PMID: 18228037 DOI: 10.1007/s00424-008-0444-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2007] [Revised: 12/13/2007] [Accepted: 01/02/2008] [Indexed: 12/19/2022]
Abstract
Voltage-gated sodium channels play a crucial role in the initiation and propagation of neuronal action potentials. Genistein, an isoflavone phytoestrogen, has long been used as a broad-spectrum inhibitor of protein tyrosine kinases (PTK). In addition, genistein-induced modulation of ion channels has been described previously in the literature. In this study, we investigated the effect of genistein on voltage-gated sodium channels in rat superior cervical ganglia (SCG) neurons. The results show that genistein inhibits Na(+) currents in a concentration-dependent manner, with a concentration of half-maximal effect (IC(50)) at 9.1 +/- 0.9 microM. Genistein positively shifted the voltage dependence of activation but did not affect inactivation of the Na(+) current. The inactive genistein analog daidzein also inhibited Na(+) currents, but was less effective than genistein. The IC(50) for daidzein-induced inhibition was 20.7 +/- 0.1 microM. Vanadate, an inhibitor of protein tyrosine phosphatases, partially but significantly reversed genistein-induced inhibition of Na(+) currents. Other protein tyrosine kinase antagonists such as tyrphostin 23, an erbstatin analog, and PP2 all had small but significant inhibitory effects on Na(+) currents. Among all active and inactive tyrosine kinase inhibitors tested, genistein was the most potent inhibitor of Na(+) currents. These results suggest that genistein inhibits Na(+) currents in rat SCG neurons through two distinct mechanisms: protein tyrosine kinase-independent, and protein tyrosine kinase-dependent mechanisms. Furthermore, the Src kinase family may be involved in the basal phosphorylation of the Na(+) channel.
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16
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Yasui S, Mawatari K, Kawano T, Morizumi R, Hamamoto A, Furukawa H, Koyama K, Nakamura A, Hattori A, Nakano M, Harada N, Hosaka T, Takahashi A, Oshita S, Nakaya Y. Insulin activates ATP-sensitive potassium channels via phosphatidylinositol 3-kinase in cultured vascular smooth muscle cells. J Vasc Res 2007; 45:233-43. [PMID: 18097147 DOI: 10.1159/000112545] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2007] [Accepted: 10/14/2007] [Indexed: 11/19/2022] Open
Abstract
The effects of insulin on the vasculature are significant because insulin resistance is associated with hypertension. To increase the understanding of the effects of insulin on the vasculature, we analyzed changes in potassium ion transport in cultured vascular smooth muscle cells (VSMCs). Using the potential-sensitive fluorescence dye bis-(1,3-dibutylbarbituric acid)trimethine oxonol [DiBAC4(3)], we found that insulin induced membrane hyperpolarization after 2 min in A10 cells. Insulin-induced hyperpolarization was suppressed by glibenclamide, an ATP-sensitive potassium (K(ATP)) channel blocker. Using a cell-attached patch clamp experiment, the K(ATP) channel was activated by insulin in both A10 cells and isolated VSMCs from rat aortas, indicating that insulin causes membrane hyperpolarization via K(ATP) channel activation. These effects were not dependent on intracellular ATP concentration, but wortmannin, a phosphatidylinositol 3-kinase (PI3-K) inhibitor, significantly suppressed insulin-induced K(ATP) channel activation. In addition, insulin enhanced phosphorylation of insulin receptor, insulin receptor substrate (IRS)-1 and protein kinase B (Akt) after 2 min. These data suggest that K(ATP) channel activation by insulin is mediated by PI3-K. Furthermore, using a nitric oxide synthase (NOS) inhibitor, we found that NOS might play an important role downstream of PI3-K in insulin-induced K(ATP) channel activation. This study may contribute to our understanding of mechanisms of insulin resistance-associated hypertension.
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Affiliation(s)
- Sonoko Yasui
- Department of Nutrition and Metabolism, University of Tokushima Graduate School, Tokushima, Japan
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Artigas P, Al'aref SJ, Hobart EA, Díaz LF, Sakaguchi M, Straw S, Andersen OS. 2,3-butanedione monoxime affects cystic fibrosis transmembrane conductance regulator channel function through phosphorylation-dependent and phosphorylation-independent mechanisms: the role of bilayer material properties. Mol Pharmacol 2006; 70:2015-26. [PMID: 16966478 DOI: 10.1124/mol.106.026070] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
2,3-Butanedione monoxime (BDM) is widely believed to act as a chemical phosphatase. We therefore examined the effects of BDM on the cystic fibrosis transmembrane regulator (CFTR) Cl(-) channel, which is regulated by phosphorylation in a complex manner. In guinea pig ventricular myocytes, forskolin-activated whole-cell CFTR currents responded biphasically to external 20 mM BDM: a rapid approximately 2-fold current activation was followed by a slower (tau approximately 20 s) inhibition (to approximately 20% of control). The inhibitory response was abolished by intracellular dialysis with the phosphatase inhibitor microcystin, suggesting involvement of endogenous phosphatases. The BDM-induced activation was studied further in Xenopus laevis oocytes expressing human epithelial CFTR. The concentration for half-maximal BDM activation (K(0.5)) was state-dependent, approximately 2 mM for highly and approximately 20 mM for partially phosphorylated channels, suggesting a modulated receptor mechanism. Because BDM modulates many different membrane proteins with similar K(0.5) values, we tested whether BDM could alter protein function by altering lipid bilayer properties rather than by direct BDM-protein interactions. Using gramicidin channels of different lengths (different channel-bilayer hydrophobic mismatch) as reporters of bilayer stiffness, we found that BDM increases channel appearance rates and lifetimes (reduces bilayer stiffness). At 20 mM BDM, the appearance rates increase approximately 4-fold (for the longer, 15 residues/monomer, channels) to approximately 10-fold (for the shorter, 13 residues/monomer channels); the lifetimes increase approximately 50% independently of channel length. BDM thus reduces the energetic cost of bilayer deformation, an effect that may underlie the effects of BDM on CFTR and other membrane proteins; the state-dependent changes in K(0.5) are consistent with such a bilayer-mediated mechanism.
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Affiliation(s)
- Pablo Artigas
- Laboratory of Cardiac/Membrane Physiology, The Rockefeller University, 1230 York Ave., New York, NY 10021, USA.
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18
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Han NLR, Ye JS, Yu ACH, Sheu FS. Differential mechanisms underlying the modulation of delayed-rectifier K+ channel in mouse neocortical neurons by nitric oxide. J Neurophysiol 2006; 95:2167-78. [PMID: 16421196 DOI: 10.1152/jn.01185.2004] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The modulatory effects of nitric oxide (NO) on voltage-dependent K+ channels are intricate. In our present study, the augmentation and reduction of K+ currents by NO donor S-nitro-N-acetylpenicillamine (SNAP) and pure dissolved NO was observed in dissociated neurons from mice neocortex with both whole cell and cell-attached patch clamp. By using a specific electrochemical sensor, the critical concentrations of NO that increased or reduced the channel activities were accurately quantified. Low concentrations of SNAP (20 microM) or NO solution (0.1 microM) enhanced whole cell delayed rectifier K+ -current (IK) and left the fast inactivating A current (IA) unchanged. However, high concentrations of SNAP (100 microM) and NO (0.5 microM) reduced both IK and IA currents. In cell-attached experiments, a significant increase in channel open probability (NP0) was observed when using low concentrations of SNAP or NO. High concentrations of SNAP or NO dramatically decreased NP0. The increase in channel activities by low concentrations of SNAP was abolished in the presence of either inhibitors of soluble guaylate cyclase or inhibitors of cGMP-dependent protein kinase G, suggesting a link to the NO-cGMP signaling cascade. The reduction of channel activities by high concentrations of SNAP was reversed by the reducing agent dithiothreitol, implying a redox reaction mechanism. Thus both NO-cGMP signaling and a redox mechanism are involved in the modulation of IK channel activity for neuron excitability.
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Affiliation(s)
- Nian-Lin R Han
- Department of Biological Sciences, National University of Singapore, Singapore
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19
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Teisseyre A, Michalak K. Genistein inhibits the activity of kv1.3 potassium channels in human T lymphocytes. J Membr Biol 2006; 205:71-9. [PMID: 16283587 DOI: 10.1007/s00232-005-0764-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2005] [Revised: 06/21/2005] [Indexed: 10/25/2022]
Abstract
In the present study, the whole-cell patch-clamp technique was applied to follow the inhibitory effect of genistein--a tyrosine kinase inhibitor and a natural anticancer agent--on the activity of voltage-gated potassium channels Kv1.3 expressed in human T lymphocytes (TL). Obtained data provide evidence that genistein application in the concentration range of 1-80 microM reversibly decreased the whole-cell potassium currents in TL in a concentration-dependent manner to about 0.23 of the control value. The half-blocking concentration range of genistein was from 10 to 40 microM. The current inhibition was correlated in time with a significant decrease of the current activation rate. The steady-state activation of the currents was unchanged upon application of genistein, as was the inactivation rate. The inhibitory effect of genistein on the current amplitude and activation kinetics was voltage-independent. The current inhibition was not changed significantly in the presence of 1 mM of sodium orthovanadate, a tyrosine phosphatase inhibitor. Application of daidzein, an inactive genistein analogue, did not affect significantly either the current amplitudes or the activation kinetics. Possible mechanisms of the observed phenomena and their significance for genistein-induced inhibition of cancer cell proliferation are discussed.
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Affiliation(s)
- A Teisseyre
- Department of Biophysics, Wrocław Medical University, ul. Chałubińskiego 10, Wrocław, Poland.
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20
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Altomare C, Tognati A, Bescond J, Ferroni A, Baruscotti M. Direct inhibition of the pacemaker (If) current in rabbit sinoatrial node cells by genistein. Br J Pharmacol 2006; 147:36-44. [PMID: 16273123 PMCID: PMC1615846 DOI: 10.1038/sj.bjp.0706433] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2005] [Revised: 09/14/2005] [Accepted: 09/14/2005] [Indexed: 11/09/2022] Open
Abstract
Genistein is a tyrosine kinase inhibitor which interferes with the activity of several ionic channels either by altering modulatory phosphorylating processes or by direct binding. In whole-cell conditions, genistein induces a partial inhibition of the pacemaker (I(f)) current recorded in cardiac sinoatrial and ventricular myocytes. We investigated the mechanism of action of genistein (50 microM) on the I(f) current in whole-cell, cell-attached, and inside-out configurations, and the measured fractional inhibitions were similar: 26.6, 27.2, and 33.6%, respectively. When ATP was removed from the whole-cell pipette solution no differences were revealed in the effect of the drug when compared to metabolically active cells. Genistein fully maintained its blocking ability even when herbimycin, a tyrosine kinase inhibitor, was added to the whole-cell ATP-free pipette solution. Genistein-induced block was independent of the gating state of the channel and did not display voltage or current dependence; this independence distinguishes genistein from all other f-channel blockers. When inside-out experiments were performed to test for a direct interaction with the channel, genistein, superfused on the intracellular side of the membrane, decreased the maximal I(f) conductance, and slightly shifted the current-activation curve to the left. Furthermore, the effect of genistein was independent of cAMP modulation. We conclude that, in addition to its tyrosine kinase-inhibitory properties, genistein also blocks I(f) by directly interacting with the channel, and thus cannot be considered a valuable pharmacological tool to investigate phosphorylation-dependent modulatory pathways of the I(f) current and of cardiac rhythm.
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Affiliation(s)
- Claudia Altomare
- Department of Biomolecular Sciences and Biotechnology, Laboratory of Molecular Physiology and Neurobiology, University of Milan, via Celoria 26, 20133 Milano, Italy
| | - Agnese Tognati
- Department of Biomolecular Sciences and Biotechnology, Laboratory of Molecular Physiology and Neurobiology, University of Milan, via Celoria 26, 20133 Milano, Italy
| | - Jocelyn Bescond
- Institut de Biologie et Physiologie Cellulaire UMR 6187 CNRS, Université de Poitiers Pôle Biologie Santé, 40 avenue du Recteur Pineau, 86022 Poitiers cedex, France
| | - Arnaldo Ferroni
- Department of Biomolecular Sciences and Biotechnology, Laboratory of Molecular Physiology and Neurobiology, University of Milan, via Celoria 26, 20133 Milano, Italy
| | - Mirko Baruscotti
- Department of Biomolecular Sciences and Biotechnology, Laboratory of Molecular Physiology and Neurobiology, University of Milan, via Celoria 26, 20133 Milano, Italy
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Ward JPT, Knock GA, Snetkov VA, Aaronson PI. Protein kinases in vascular smooth muscle tone--role in the pulmonary vasculature and hypoxic pulmonary vasoconstriction. Pharmacol Ther 2005; 104:207-31. [PMID: 15556675 DOI: 10.1016/j.pharmthera.2004.08.009] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Hypoxic pulmonary vasoconstriction (HPV) is an adaptive mechanism that in the normal animal diverts blood away from poorly ventilated areas of the lung, thereby maintaining optimal ventilation-perfusion matching. In global hypoxia however, such as in respiratory disease or at altitude, it causes detrimental increases in pulmonary vascular resistance and pulmonary artery (PA) pressure. The precise intracellular pathways and mechanisms underlying HPV remain unclear, although it is now recognised that both an elevation in smooth muscle intracellular [Ca2+] and a concomitant increase in Ca2+ sensitivity are involved. Several key intracellular protein kinases have been proposed as components of the signal transduction pathways leading to development of HPV, specifically Rho kinase, non-receptor tyrosine kinases (NRTK), p38 mitogen activated protein (MAP) kinase, and protein kinase C (PKC). All of these have been implicated to a greater or lesser extent in pathways leading to Ca2+ sensitisation, and in some cases regulation of intracellular [Ca2+] as well. In this article, we review the role of these key protein kinases in the regulation of vascular smooth muscle (VSM) constriction, applying what is known in the systemic circulation to the pulmonary circulation and HPV. We conclude that the strongest evidence for direct involvement of protein kinases in the mechanisms of HPV concerns a central role for Rho kinase in Ca2+ sensitisation, and a potential role for Src-family kinases in both modulation of Ca2+ entry via capacitative Ca2+ entry (CCE) and activation of Rho kinase, though others are likely to have indirect or modulatory influences. In addition, we speculate that Src family kinases may provide a central interface between the proposed hypoxia-induced generation of reactive oxygen species by mitochondria and both the elevation in intracellular [Ca2+] and Rho kinase mediated Ca2+ sensitisation.
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Affiliation(s)
- Jeremy P T Ward
- Division of Asthma, Allergy and Lung Biology, Guy's, King's and St Thomas' School of Medicine, King's College London, London, UK.
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22
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Kuhlmann CRW, Wu Y, Li F, Münz BM, Tillmanns H, Waldecker B, Wiecha J. bFGF activates endothelial Ca2+-activated K+ channels involving G-proteins and tyrosine kinases. Vascul Pharmacol 2005; 41:181-6. [PMID: 15653093 DOI: 10.1016/j.vph.2004.10.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2004] [Revised: 10/20/2004] [Accepted: 10/22/2004] [Indexed: 11/27/2022]
Abstract
Activation of Ca2+-activated K+ channels (BK(Ca)) has been shown to be an important step in the basic fibroblast growth factor (bFGF)-induced proliferation of endothelial cells. In this study, we investigate the signaling cascades of BK(Ca) modulation by bFGF. Using the patch-clamp technique, bFGF (50 ng/ml) significantly increased the BK(Ca) open-state probability in cultured endothelial cells derived from human coronary arteries after 6 min (n=26, p<0.01), which lasted up the whole recording time of 60 min. After preincubation with pertussis toxin (100 ng/ml), bFGF superfusion did not cause a significant increase of BK(Ca) activity until 25 min had passed. When genistein was supplemented to the bath solution, a significant activation of BK(Ca) by bFGF was observed during a time interval of 6-20 min (n=17, p<0.01). In contrast, the addition of the inactive analogue daidzein did not change bFGF-induced activation of the BK(Ca). In conclusion, the results of the present study indicate that the early activation of the BK(Ca) by bFGF is mediated by G-protein-dependent mechanisms, whereas the later effect is due to a tyrosine kinase-dependent signaling pathway.
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Kinoshita H, Azma T, Nakahata K, Iranami H, Kimoto Y, Dojo M, Yuge O, Hatano Y. Inhibitory effect of high concentration of glucose on relaxations to activation of ATP-sensitive K+ channels in human omental artery. Arterioscler Thromb Vasc Biol 2004; 24:2290-5. [PMID: 15486306 DOI: 10.1161/01.atv.0000148006.78179.c7] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
OBJECTIVE The present study was designed to examine in the human omental artery whether high concentrations of D-glucose inhibit the activity of ATP-sensitive K+ channels in the vascular smooth muscle and whether this inhibitory effect is mediated by the production of superoxide. METHODS AND RESULTS Human omental arteries without endothelium were suspended for isometric force recording. Changes in membrane potentials were recorded and production of superoxide was evaluated. Glibenclamide abolished vasorelaxation and hyperpolarization in response to levcromakalim. D-glucose (10 to 20 mmol/L) but not l-glucose (20 mmol/L) reduced these vasorelaxation and hyperpolarization. Tiron and diphenyleneiodonium, but not catalase, restored vasorelaxation and hyperpolarization in response to levcromakalim in arteries treated with D-glucose. Calphostin C and Gö6976 simultaneously recovered these vasorelaxation and hyperpolarization in arteries treated with D-glucose. Phorbol 12-myristate 13 acetate (PMA) inhibited the vasorelaxation and hyperpolarization, which are recovered by calphostin C as well as Gö6976. D-glucose and PMA, but not l-glucose, significantly increased superoxide production from the arteries, whereas such increased production was reversed by Tiron. CONCLUSIONS These results suggest that in the human visceral artery, acute hyperglycemia modulates vasodilation mediated by ATP-sensitive K+ channels via the production of superoxide possibly mediated by the activation of protein kinase C.
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Affiliation(s)
- Hiroyuki Kinoshita
- Department of Anesthesia, Japanese Red Cross Society, Wakayama Medical Center, Japan.
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Dubrovska G, Verlohren S, Luft FC, Gollasch M. Mechanisms of ADRF release from rat aortic adventitial adipose tissue. Am J Physiol Heart Circ Physiol 2003; 286:H1107-13. [PMID: 14644761 DOI: 10.1152/ajpheart.00656.2003] [Citation(s) in RCA: 125] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Blood vessels are surrounded by variable amounts of adipose tissue. We showed earlier that adventitial adipose tissue inhibits rat aortic contraction by release of a transferable factor, adventitium-derived relaxing factor (ADRF), which activates smooth muscle K(+) channels. However, little is known about the mechanisms of ADRF release. Using isolated rat aortic rings and isometric contraction measurements, we show that ADRF release depends on extracellular [Ca(2+)] (EC(50) approximately 4.7 mM). ADRF effects do not involve neuronal presynaptic N-type Ca(2+) and Na(+) channels or vanilloid, cannabinoid, and CGRP receptors. ADRF release is strongly inhibited by the protein tyrosine kinase inhibitors genistein and tyrphostin A25. In contrast, daidzein, an inactive genistein analog, and the protein tyrosine kinase inhibitor ST638 had no effect. Protein kinase A inhibition by H89 also inhibited ADRF release, whereas the protein kinase G inhibitor KT-5823 had no effect. We propose that ADRF release is Ca(2+) dependent and is regulated by intracellular signaling pathways involving tyrosine kinase and protein kinase A. Furthermore, ADRF release does not depend on perivascular nerve endings.
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Zhu L, Jiang ZL, Krnjević K, Wang FS, Ye JH. Genistein directly blocks glycine receptors of rat neurons freshly isolated from the ventral tegmental area. Neuropharmacology 2003; 45:270-80. [PMID: 12842133 DOI: 10.1016/s0028-3908(03)00151-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The effects of tyrosine kinase inhibitors on the glycine-induced current (I(Gly)) were studied in rat neurons freshly isolated from the ventral tegmental area (VTA). Genistein reversibly and concentration-dependently depressed I(Gly), with an IC(50) of 13 microM. Preincubation with genistein had no effect on I(Gly), indicating that genistein is effective only when glycine is bound to the receptor and channels are most likely open. Genistein depressed maximum I(Gly) without significantly changing the EC(50) for glycine. Genistein-induced inhibition of I(Gly) was sensitive to membrane voltage, being greater at positive membrane potentials. A kinetic analysis indicated that genistein lengthens the time constant of I(Gly) activation, but has no effect on deactivation or desensitization. When genistein was rapidly washed out, a transient rebound current probably reflected a faster dissociation of genistein, with respect to glycine. Results of competition experiments suggest that genistein acts on the same region of the glycine receptor as picrotoxin. Daidzein, an analog of genistein that does not act on protein kinases, also inhibited I(Gly). Co-application of lavendustin A, a specific inhibitor of tyrosine kinase, had no effect on I(Gly). Our results extend to neurons isolated from the VTA, the previous finding that genistein directly inhibits glycine receptors of hypothalamic brain slices.
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Affiliation(s)
- L Zhu
- New Jersey Medical School (UMDNJ), Rutgers-UMDNJ Integrative Neuroscience Program, Department of Anesthesiology, 185, South Orange Avenue, Newark, NJ 07103-2714, USA
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Dawn B, Takano H, Tang XL, Kodani E, Banerjee S, Rezazadeh A, Qiu Y, Bolli R. Role of Src protein tyrosine kinases in late preconditioning against myocardial infarction. Am J Physiol Heart Circ Physiol 2002; 283:H549-56. [PMID: 12124200 DOI: 10.1152/ajpheart.00873.2001] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Although Src protein tyrosine kinases (PTKs) have been shown to be essential in late preconditioning (PC) against myocardial stunning, their role in triggering versus mediating late PC against myocardial infarction remains unclear. Four groups of conscious rabbits were subjected to a 30-min coronary occlusion on day 2, with or without PC ischemia on day 1. Administration of the Src PTK inhibitor lavendustin A (LD-A; 1 mg/kg iv) before the PC ischemia on day 1 (group III, n = 7) failed to block the delayed protective effect against myocardial infarction 24 h later. Late PC against infarction, however, was completely abrogated when LD-A was given 24 h after the PC ischemia, prior to the 30-min occlusion on day 2 (group IV, n = 8). We conclude that, in conscious rabbits, Src PTK activity is necessary for the mediation of late PC protection against myocardial infarction on day 2, but not for the initiation of this phenomenon on day 1. Taken together with previous studies in the setting of stunning, these findings reveal heretofore unrecognized differences in the roles of Src PTKs in late PC against stunning versus late PC against infarction.
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Affiliation(s)
- Buddhadeb Dawn
- Experimental Research Laboratory, Division of Cardiology, University of Louisville, Louisville, KY 40292, USA
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27
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Ogura T, Imanishi S, Shibamoto T. Activation of background membrane conductance by the tyrosine kinase inhibitor tyrphostin A23 and its inactive analog tyrphostin A1 in guinea pig ventricular myocytes. JAPANESE JOURNAL OF PHARMACOLOGY 2001; 87:235-9. [PMID: 11885974 DOI: 10.1254/jjp.87.235] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
ABSTRACT-The effects of the tyrosine kinase (TK) inhibitor tyrphostin A23 and its inactive analog tyrphostin Al on background membrane conductance were investigated in guinea pig ventricular myocytes. TK-inhibiting A23 reversibly increased membrane conductance under conditions designed to minimize Na+, Ca2+, K+, and Na+-K+ pump currents. Similar stimulatory action was obtained with TK-inactive Al. The tyrphostin-induced current was inhibited by omitting external Na+ or Ca+, suppressed by chelating internal Ca2+, blocked by external Cd2+ and Ni2+, and insensitive to changes in internal Cl- concentration. We conclude that tyrphostins have a direct, TK-independent action that increases membrane conductance probably by stimulating Na+-Ca2+ exchange.
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Affiliation(s)
- T Ogura
- Second Department of Physiology, Kanazawa Medical University, Kahoku-gun, Ishikawa, Japan.
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28
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Lin JH, Rydqvist B. Characterization of a delayed rectifier potassium channel in the slowly adapting stretch receptor neuron of crayfish. Brain Res 2001; 913:1-9. [PMID: 11532241 DOI: 10.1016/s0006-8993(01)02737-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Single channel recordings were performed on enzyme-cleaned slowly adapting sensory neurons of crayfish, in cell-attached configuration, with a physiological K(+) gradient across the neuronal membrane. An outward rectifying, voltage-gated K(+) channel with a slope conductance of 13 pS and a K(+) ion permeability of P(K)=6.5 x 10(-14) cm(3)/s was characterized. This 13 pS K(+) channel started to be activated at around 20 mV depolarization. Its open probability increased upon depolarization with V(0.5)= -25.3 mV and P(max)=0.83. The averaged currents showed a delay following the onset of depolarization. The activation time constant was voltage-dependent. The maximal value was 17.0 ms at -25 mV and at +35 mV the time constant was 1.7 ms. Little inactivation was observed throughout the 80- or 1500-ms long depolarization pulses. A sum of two exponentials provided the optimal fit for open time and closed time distribution. At 80-mV depolarization, the open time constants were 0.4 and 10.4 ms; the close time constants were 0.4 and 2.3 ms. The first-latency distribution suggested that at least two closed states preceded two open states. This 13 pS delayed rectifier plays a minor role in the maintenance of the resting membrane potential but contributes to the action potential repolarization. It may also modify the stretch-induced receptor potential and affect the adaptation behaviours in this neuron.
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Affiliation(s)
- J H Lin
- Department of Physiology and Pharmacology, Karolinska Institutet, S-171 77, Stockholm, Sweden
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29
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Jhamandas JH, Cho C, Jassar B, Harris K, MacTavish D, Easaw J. Cellular mechanisms for amyloid beta-protein activation of rat cholinergic basal forebrain neurons. J Neurophysiol 2001; 86:1312-20. [PMID: 11535679 DOI: 10.1152/jn.2001.86.3.1312] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The deposition of amyloid beta-protein (Abeta) in the brain and the loss of cholinergic neurons in the basal forebrain are two pathological hallmarks of Alzheimer's disease (AD). Although the mechanism of Abeta neurotoxicity is unknown, these cholinergic neurons display a selective vulnerability when exposed to this peptide. In this study, application of Abeta(25-35) or Abeta(1-40) to acutely dissociated rat neurons from the basal forebrain nucleus diagonal band of Broca (DBB), caused a decrease in whole cell voltage-activated currents in a majority of cells. This reduction in whole cell currents occurs through a modulation of a suite of potassium conductances including calcium-activated potassium (I(C)), the delayed rectifier (I(K)), and transient outward potassium (I(A)) conductances, but not calcium or sodium currents. Under current-clamp conditions, Abeta evoked an increase in excitability and a loss of accommodation in cholinergic DBB neurons. Using single-cell RT-PCR technique, we determined that Abeta actions were specific to cholinergic, but not GABAergic DBB neurons. Abeta effects on whole cell currents were occluded in the presence of membrane-permeable protein tyrosine kinase inhibitors, genistein and tyrphostin B-44. Our data indicate that the Abeta actions on specific potassium conductances are modulated through a protein tyrosine kinase pathway and that these effects are selective to cholinergic but not GABAergic cells. These observations provide a cellular basis for the selectivity of Abeta neurotoxicity toward cholinergic basal forebrain neurons that are at the epicenter of AD pathology.
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Affiliation(s)
- J H Jhamandas
- Division of Neurology, Department of Medicine, University of Alberta, Edmonton, Alberta T6G 2S2, Canada.
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30
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Okamoto F, Okabe K, Kajiya H. Genistein, a soybean isoflavone, inhibits inward rectifier K(+) channels in rat osteoclasts. THE JAPANESE JOURNAL OF PHYSIOLOGY 2001; 51:501-9. [PMID: 11564287 DOI: 10.2170/jjphysiol.51.501] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Genistein, a soybean-derived isoflavone with an inhibitory effect on protein tyrosine kinases (PTKs), has been shown to suppress osteoclastic bone resorption. To clarify the mechanisms underlying this action, we investigated the effects of genistein on inward rectifier K(+) current (I(Kir)) in rat osteoclasts by using the whole-cell patch-clamp technique. Extracellularly applied genistein inhibited I(Kir) in a concentration-dependent manner. Physiologically attainable concentrations of genistein inhibited I(Kir). IC(50) values obtained 5 and 10 min after the application of genistein were 54 and 27 microM, respectively. The removal of genistein partially restored the current. Daidzein, an isoflavone without PTK-inhibiting activity, also showed a weak inhibitory effect on I(Kir), but genistin had no effect. Other PTK inhibitors, tyrphostin A25, tyrphostin B42, and tyrphostin B46, inhibited I(Kir), whereas herbimycin A and lavendustin A were without effect. The inactive tyrphostin, A1, showed a similar inhibitory effect as tyrphostin A25. The tyrosine phosphatase inhibitor, orthovanadate, did not affect the inhibitory potency of genistein on I(Kir). The inhibitory action of genistein was unaffected by changing intracellular Ca(2+) concentration ([Ca(2+)]i) or by pretreatment of the cell with GDPbetaS, Rp-cAMPS, okadaic acid, or staurosporine. Therefore the inhibition of I(Kir) by genistein does not depend on PTK inhibition, involvement of changes in [Ca(2+)]i, or secondary interaction with protein kinase A or protein kinase C. Genistein-induced inhibition of I(Kir) would cause membrane depolarization, elevation of [Ca(2+)]i, and inhibition of osteoclastic bone resorption.
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Affiliation(s)
- F Okamoto
- Department of Oral Physiology, Fukuoka Dental College, Fukuoka, 814-0193, Japan.
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31
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Huang RQ, Dillon GH. Direct inhibition of glycine receptors by genistein, a tyrosine kinase inhibitor. Neuropharmacology 2000; 39:2195-204. [PMID: 10963763 DOI: 10.1016/s0028-3908(00)00046-0] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Genistein, a tyrosine kinase inhibitor, has been widely used to examine potential effects of protein tyrosine kinase (PTK)-mediated regulation of receptor/channel function. Alteration of ion channel function in the presence of genistein has typically led to the conclusion that PTK regulates the activity of the channel under investigation. In the present report, we have assessed the possibility that genistein directly inhibits the glycine receptor, independent of effects on protein tyrosine kinase. Coapplication of genistein with glycine reversibly inhibited the strychnine-sensitive, glycine-activated current recorded from hypothalamic neurons. The time course of genistein action was rapid (within ms). Equilibration of genistein in the intracellular solution did not affect the ability of extracellularly applied genistein to inhibit the glycine response. Glycine concentration-response profiles generated in the absence and presence of genistein indicated the block was due to non-competitive antagonism. The genistein effect also displayed voltage-dependence. Daidzein, an analog of genistein that does not block protein kinases, also inhibited glycine-activated current. Coapplication of lavendustin A, a specific inhibitor of PTK, had no effect on the glycine response. Our results demonstrate that the tyrosine kinase inhibitor genistein has a direct inhibitory effect on glycine receptors that is not mediated via inhibition of PTK.
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Affiliation(s)
- R Q Huang
- Department of Pharmacology, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX 76107, USA
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32
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Cole WC, Malcolm T, Walsh MP, Light PE. Inhibition by protein kinase C of the K(NDP) subtype of vascular smooth muscle ATP-sensitive potassium channel. Circ Res 2000; 87:112-7. [PMID: 10903994 DOI: 10.1161/01.res.87.2.112] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
ATP-sensitive K(+) channels (K(ATP)) contribute to the regulation of tone in vascular smooth muscle cells. We determined the effects of protein kinase C (PKC) activation on the nucleoside diphosphate-activated (K(NDP)) subtype of vascular smooth muscle K(ATP) channel. Phorbol 12,13-dibutyrate (PdBu) and angiotensin II inhibited K(NDP) activity of C-A patches of rabbit portal vein (PV) myocytes, but an inactive phorbol ester was without effect, and pretreatment with PKC inhibitor prevented the actions of PdBu. Constitutively active PKC inhibited K(NDP) in I-O patches but was without effect in the presence of a specific peptide inhibitor of PKC. PdBu increased the duration of a long-lived interburst closed state but was without effect on burst duration or intraburst kinetics. PdBu treatment inhibited K(NDP), but not a 70-pS K(ATP) channel of rat PV. The results indicate that the K(NDP) subtype of vascular smooth muscle K(ATP) channel is inhibited by activation of PKC. Control of K(NDP) activity by intracellular signaling cascades involving PKC may, therefore, contribute to control of tone and arterial diameter by vasoconstrictors.
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Affiliation(s)
- W C Cole
- Smooth Muscle Research Group, Faculty of Medicine, University of Calgary, Alberta, Canada.
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33
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Kimura M, Obara K, Sasase T, Ishikawa T, Tanabe Y, Nakayama K. Specific inhibition of stretch-induced increase in L-type calcium channel currents by herbimycin A in canine basilar arterial myocytes. Br J Pharmacol 2000; 130:923-31. [PMID: 10864901 PMCID: PMC1572123 DOI: 10.1038/sj.bjp.0703360] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The effects of protein-tyrosine kinase (PTK) and protein-tyrosine phosphatase (PTP) inhibitors on voltage-activated barium currents (I(Ba)) through L-type calcium channels increased by hypotonic solution were investigated in canine basilar arterial myocytes by the whole-cell patch-clamp technique. I(Ba) was elicited by depolarizing step from a holding potential of -80 to +10 mV and identified by using an L-type calcium channel agonist, Bay K 8644 (100 nM), and an L-type calcium channel blocker, nicardipine (1 microM). Hypotonic superfusate induced cell swelling and acted as a stretch stimulus, which reversibly increased peak I(Ba) amplitude at +10 mV. I(Ba) was also decreased by nicardipine (1 microM) under the hypotonic condition. PTK inhibitors such as herbimycin A (30 nM), genistein (10 microM), and lavendustin A (10 microM) decreased I(Ba) enhanced by hypotonic solution. Genistein also decreased I(Ba) in a concentration-dependent manner under the isotonic condition. The inactive genistein analogue daidzein (10 microM) had no effect on I(Ba) under either the isotonic or hypotonic condition. By contrast, herbimycin A did not decrease I(Ba) under the isotonic condition. Sodium orthovanadate (10 microM), a PTP inhibitor, increased I(Ba) under both conditions. The present results suggest that cell swelling by hypotonic solution increases the L-type calcium channel currents in canine basilar artery and that herbimycin-sensitive PTK activity is primarily involved in the enhancement of calcium channel currents.
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MESH Headings
- 3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester/pharmacology
- Animals
- Barium/pharmacology
- Basilar Artery/cytology
- Benzoquinones
- Calcium Channel Agonists/pharmacology
- Calcium Channels, L-Type/drug effects
- Calcium Channels, L-Type/physiology
- Cell Size/drug effects
- Dogs
- Dose-Response Relationship, Drug
- Enzyme Inhibitors/pharmacology
- Female
- Genistein/pharmacology
- Hypotonic Solutions/pharmacology
- Isoflavones/pharmacology
- Isotonic Solutions/pharmacology
- Lactams, Macrocyclic
- Male
- Membrane Potentials/drug effects
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/physiology
- Nicardipine/pharmacology
- Osmolar Concentration
- Patch-Clamp Techniques
- Phenols/pharmacology
- Physical Stimulation
- Protein-Tyrosine Kinases/antagonists & inhibitors
- Quinones/pharmacology
- Rifabutin/analogs & derivatives
- Vanadates/pharmacology
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Affiliation(s)
- Makoto Kimura
- Department of Pharmacology, School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Shizuoka City, Shizuoka 422-8526, Japan
| | - Kazuo Obara
- Department of Pharmacology, School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Shizuoka City, Shizuoka 422-8526, Japan
- Author for correspondence:
| | - Tomohiko Sasase
- Department of Pharmacology, School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Shizuoka City, Shizuoka 422-8526, Japan
| | - Tomohisa Ishikawa
- Department of Pharmacology, School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Shizuoka City, Shizuoka 422-8526, Japan
| | - Yoshiyuki Tanabe
- Department of Pharmacology, School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Shizuoka City, Shizuoka 422-8526, Japan
| | - Koichi Nakayama
- Department of Pharmacology, School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Shizuoka City, Shizuoka 422-8526, Japan
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34
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Matsushita Y, Henmi S, Muraki K, Imaizumi Y, Watanabe M. Cromakalim-induced membrane current in guinea-pig tracheal smooth muscle cells. Eur J Pharmacol 2000; 389:51-8. [PMID: 10686295 DOI: 10.1016/s0014-2999(99)00872-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The characteristics of the cromakalim-induced membrane current were examined in single tracheal myocytes of the guinea-pig under voltage-clamp conditions. When K(+) concentrations in the pipette and bathing solutions were approximately 140 mM, cromakalim activated a membrane current (I(crom)) which was inward at -60 mV and reversed at -2 mV. I(crom) was blocked by 10 microM glibenclamide and potentiated when the ATP concentration in the pipette solution was decreased. The K(d) and Hill coefficient of glibenclamide for I(crom) block were 200 nM and 1.05, respectively. Application of the tyrosine kinase inhibitors, genistein and alpha-cyano-3-ethoxy-4-hydroxy-5-phenylthiomethylcinnamamid (ST638), reduced I(crom) in a concentration-dependent manner. Daidzein, which does not inhibit tyrosine kinase, was about 10 times less effective than genistein. Herbimycin A had no effect on I(crom). Internal application of these inhibitors from the pipette did not affect I(crom). In conclusion, cromakalim is a potent activator of the ATP-sensitive K(+) channel (K(ATP) channel) in guinea-pig tracheal myocytes. The inhibition of I(crom) by genistein and ST638 may be due to the direct block of the channel from outside.
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Affiliation(s)
- Y Matsushita
- Department of Chemical Pharmacology, Faculty of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabedori, Mizuhoku, Nagoya, Japan
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35
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Huang RQ, Fang MJ, Dillon GH. The tyrosine kinase inhibitor genistein directly inhibits GABAA receptors. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 1999; 67:177-83. [PMID: 10101245 DOI: 10.1016/s0169-328x(99)00061-3] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The protein tyrosine kinase (PTK) inhibitor genistein has been widely used to examine potential effects of tyrosine phosphorylation on neurotransmitter function. We report here that genistein inhibits GABAA receptors through a direct effect. Extracellular application of genistein and GABA reversibly inhibited GABA-activated currents recorded from HEK293 cells expressing rat alpha1beta2gamma2S or alpha1beta2 receptors, even when genistein was preequilibrated in the intracellular solution. Daidzein, an analog of genistein that does not block PTK, also inhibited GABA-activated current. Coapplication of lavendustin A, a specific inhibitor of PTK, had no effect on the GABA response. Our results demonstrate that genistein has a direct inhibitory effect on GABAA receptors that is not mediated via inhibition of tyrosine kinase.
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Affiliation(s)
- R Q Huang
- Department of Pharmacology, University of North Texas, Health Science Center at Fort Worth, 3500 Camp Bowie Blvd., Fort Worth, TX 76107, USA
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36
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Takeuchi T, Kishi M, Hirayama N, Yamaji M, Ishii T, Nishio H, Hata F, Takewaki T. Tyrosine kinase involvement in apamin-sensitive inhibitory responses of rat distal colon. J Physiol 1999; 514 ( Pt 1):177-88. [PMID: 9831725 PMCID: PMC2269060 DOI: 10.1111/j.1469-7793.1999.177af.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
1. It has been suggested that pituitary adenylate cyclase activating peptide (PACAP) may be involved in the non-adrenergic, non-cholinergic (NANC) inhibitory response of longitudinal muscle of rat distal colon. In this study, we have investigated the intracellular mechanism of PACAP-induced relaxation in this muscle. 2. PACAP induced an apamin-sensitive relaxation of the longitudinal muscle. The tyrosine kinase inhibitors genistein at 10 microM and tyrphostin 25 at 30 microM, but not the cyclic AMP-dependent protein kinase inhibitor Rp-8-bromoadenosine-3',5'-cyclic monophosphorothioate at 30 microM significantly inhibited the PACAP-induced relaxation to 60% and 25% of control values, respectively. PACAP did not increase the cyclic AMP content of the muscle. 3. Tyrphostin 25 at 10 microM significantly inhibited the relaxation of longitudinal muscle induced by electrical field stimulation (EFS), to 50% of control values. Apamin at 1 microM, an antagonist of small conductance Ca2+-activated K+ channels, also inhibited the relaxation, to 42 % of control values. The inhibitory effects of tyrphostin 25 and apamin were not additive (44 % of control values). 4. PACAP induced an apamin-sensitive, slow hyperpolarization of the cell membrane of the muscle. Tyrphostin 25 at 3 microM inhibited this PACAP-induced hyperpolarization. Tyrphostin 25 at 10 microM and genistein at 10 microM inhibited the apamin-sensitive inhibitory junction potentials induced by a single pulse of EFS. 5. The PACAP-induced relaxation of longitudinal muscle occurred with a concomitant decrease in intracellular Ca2+ levels ([Ca2+]i). Tyrphostin 25 at 10 microM and apamin at 1 microM abolished these PACAP-induced responses. 6. From these findings it is suggested that the activation of tyrosine kinase is involved in PACAP-induced relaxation of longitudinal muscle from rat distal colon, 'upstream of' the activation of apamin-sensitive K+ channels.
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Affiliation(s)
- T Takeuchi
- Department of Veterinary Pharmacology, College of Agriculture, Osaka Prefecture University, Sakai 599-8531,, Japan.
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37
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Hughes AD, Wijetunge S. Role of tyrosine phosphorylation in excitation-contraction coupling in vascular smooth muscle. ACTA PHYSIOLOGICA SCANDINAVICA 1998; 164:457-69. [PMID: 9887969 DOI: 10.1046/j.1365-201x.1998.00446.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Increasingly it is recognized that tyrosine phosphorylation plays an important part in the regulation of function in differentiated contractile vascular smooth muscle. Tyrosine kinases and phosphatases are present in large amounts in vascular smooth muscle and have been reported to influence a number of processes crucial to contraction, including ion channel gating, calcium homeostasis and sensitization of the contractile process to [Ca2+]i. This review summarizes current understanding regarding the role of tyrosine phosphorylation in excitation-contraction coupling in blood vessels.
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Affiliation(s)
- A D Hughes
- National Heart and Lung Institute, Imperial College of Science, Technology and Medicine, St Mary's Hospital, London, UK
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