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Shigenobu K, Tsuzuki S, Philippi F, Sudoh T, Ugata Y, Dokko K, Watanabe M, Ueno K, Shinoda W. Molecular Level Origin of Ion Dynamics in Highly Concentrated Electrolytes. J Phys Chem B 2023; 127:10422-10433. [PMID: 38015036 DOI: 10.1021/acs.jpcb.3c05864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
Single-ion conducting liquid electrolytes are key to achieving rapid charge/discharge in Li secondary batteries. The Li+ transference (or transport) numbers are the defining properties of such electrolytes and have been discussed in the framework of concentrated solution theories. However, the connection between macroscopic transference and microscopic ion dynamics remains unclear. Molecular dynamics simulations were performed to obtain direct information regarding the microscopic behaviors in highly concentrated electrolytes, and the relationships between these behaviors and the transference number were determined under anion-blocking conditions. Various solvents with different donor numbers (DNs) were used along with a Li salt of the weakly Lewis basic bis(fluorosulfonyl)amide anion for electrolyte preparation. Favorable ordered Li+ structuring and a continuous Li+ conduction pathway were observed for the fluoroethylene carbonate-based electrolyte due to its low DN. The properties were less pronounced at higher DNs, e.g., for the dimethyl sulfoxide-based electrolyte. The τLi-solventlife/τdipolerelax ratio was introduced as a factor for ion dynamics, and the two mechanisms of ion transport were considered an exchange mechanism (τLi-solventlife/τdipolerelax < 1) and a vehicle mechanism (translational motion of solvated Li+) (τLi-solventlife/τdipolerelax ≥ 1). Vehicle-type transport was dominant with high DNs, while exchangeable transport was preferable at lower DNs. These findings should aid the further selection of solvents and Li salts to prepare single-ion conducting electrolytes.
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Affiliation(s)
- Keisuke Shigenobu
- Research Institute for Interdisciplinary Science, Okayama University, 3-1-1 Tsushima-Naka, Kita-ku, Okayama 700-8530, Japan
| | - Seiji Tsuzuki
- Department of Chemistry and Life Science, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan
| | - Frederik Philippi
- Department of Chemistry and Life Science, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan
| | - Taku Sudoh
- Department of Chemistry and Life Science, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan
| | - Yosuke Ugata
- Department of Chemistry and Life Science, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan
- Advanced Chemical Energy Research Centre (ACERC), Institute of Advanced Sciences, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan
| | - Kaoru Dokko
- Department of Chemistry and Life Science, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan
- Advanced Chemical Energy Research Centre (ACERC), Institute of Advanced Sciences, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan
| | - Masayoshi Watanabe
- Advanced Chemical Energy Research Centre (ACERC), Institute of Advanced Sciences, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan
| | - Kazuhide Ueno
- Department of Chemistry and Life Science, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan
- Advanced Chemical Energy Research Centre (ACERC), Institute of Advanced Sciences, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan
| | - Wataru Shinoda
- Research Institute for Interdisciplinary Science, Okayama University, 3-1-1 Tsushima-Naka, Kita-ku, Okayama 700-8530, Japan
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Shigenobu K, Sudoh T, Murai J, Dokko K, Watanabe M, Ueno K. Ion Transport in Glyme- and Sulfolane-Based Highly Concentrated Electrolytes. CHEM REC 2023; 23:e202200301. [PMID: 36802142 DOI: 10.1002/tcr.202200301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 01/31/2023] [Indexed: 02/20/2023]
Abstract
Highly concentrated electrolytes (HCEs) have a similarity to ionic liquids (ILs) in high ionic nature, and indeed some of HECs are found to behave like an IL. HCEs have attracted considerable attention as prospective candidates for electrolyte materials in future lithium secondary batteries owing to their favorable properties both in the bulk and at the electrochemical interface. In this study, we highlight the effects of the solvent, counter anion, and diluent of HCEs on the Li+ ion coordination structure and transport properties (e. g., ionic conductivity and apparent Li+ ion transference number measured under anion-blocking conditions,t L i a b c ${{t}_{{\rm L}{\rm i}}^{{\rm a}{\rm b}{\rm c}}}$ ). Our studies on dynamic ion correlations unveiled the difference in the ion conduction mechanisms in HCEs and their intimate relevance tot L i a b c ${{t}_{{\rm L}{\rm i}}^{{\rm a}{\rm b}{\rm c}}}$ values. Our systematic analysis of the transport properties of HCEs also suggests the need for a compromise to simultaneously achieve high ionic conductivity and hight L i a b c ${{t}_{{\rm L}{\rm i}}^{{\rm a}{\rm b}{\rm c}}}$ values.
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Affiliation(s)
- Keisuke Shigenobu
- Department of Chemistry and Life Science, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama, 240-8501, Japan
| | - Taku Sudoh
- Department of Chemistry and Life Science, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama, 240-8501, Japan
| | - Junichi Murai
- Department of Chemistry and Life Science, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama, 240-8501, Japan
| | - Kaoru Dokko
- Department of Chemistry and Life Science, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama, 240-8501, Japan
- Institute of Advanced Sciences, Y, okohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama, 240-8501, Japan
| | - Masayoshi Watanabe
- Institute of Advanced Sciences, Y, okohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama, 240-8501, Japan
| | - Kazuhide Ueno
- Department of Chemistry and Life Science, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama, 240-8501, Japan
- Institute of Advanced Sciences, Y, okohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama, 240-8501, Japan
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Tsuzuki S, Ikeda S, Shinoda W, Shigenobu K, Ueno K, Dokko K, Watanabe M. Molecular Dynamics Simulations of High-Concentration Li[TFSA] Sulfone Solution: Effect of Easy Conformation Change of Sulfolane on Fast Diffusion of Li Ion. J Phys Chem B 2023. [PMID: 37428625 DOI: 10.1021/acs.jpcb.3c02009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/12/2023]
Abstract
The parameters of the polarizable force field used for molecular dynamics simulations of Li diffusion in high-concentration lithium bis(trifluoromethanesulfonyl)amide (Li[TFSA]) sulfone (sulfolane, dimethylsulfone, ethylmethylsulfone, and ethyl-i-propylsulfone) solutions were refined. The densities of the solutions obtained by molecular dynamics simulations reproduced well the experimental values. The calculated concentration, temperature, and solvent dependencies of self-diffusion coefficients of ions and solvents in the mixtures well reproduce the experimentally observed dependencies. Ab initio calculations show that the intermolecular interactions between Li ions and four sulfones are not largely different. Conformational analyses show that sulfolane can change the conformation more easily owing to lower barrier height for pseudorotation compared to the rotational barrier heights of diethylsulfone and ethylmethylsulfone. Molecular dynamics simulations indicate that the easy conformation change of solvent affects the rotational relaxation of the solvent and the diffusion of Li ion in the mixture. The easy conformation change of sulfolane is one of the causes of faster diffusion of Li ion in the mixture of Li[TFSA] and sulfolane compared to the mixtures of smaller dimethylsulfone and ethylmethylsulfone.
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Affiliation(s)
- Seiji Tsuzuki
- Advanced Chemical Energy Research Centre (ACERC), Institute of Advanced Sciences, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan
| | - Shuhei Ikeda
- Department of Materials Chemistry, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
| | - Wataru Shinoda
- Research Institute for Interdisciplinary Science, Okayama University, 3-1-1 Tsushima-Naka, Kita-ku, Okayama 700-8530, Japan
| | - Keisuke Shigenobu
- Department of Chemistry and Life Science, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan
| | - Kazuhide Ueno
- Advanced Chemical Energy Research Centre (ACERC), Institute of Advanced Sciences, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan
- Department of Chemistry and Life Science, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan
| | - Kaoru Dokko
- Advanced Chemical Energy Research Centre (ACERC), Institute of Advanced Sciences, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan
- Department of Chemistry and Life Science, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan
| | - Masayoshi Watanabe
- Advanced Chemical Energy Research Centre (ACERC), Institute of Advanced Sciences, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan
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Shigenobu K, Philippi F, Tsuzuki S, Kokubo H, Dokko K, Watanabe M, Ueno K. On the concentration polarisation in molten Li salts and borate-based Li ionic liquids. Phys Chem Chem Phys 2023; 25:6970-6978. [PMID: 36804678 DOI: 10.1039/d2cp05710g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Electrolytes that transport only Li ions play a crucial role in improving rapid charge and discharge properties in Li secondary batteries. Single Li-ion conduction can be achieved via liquid materials such as Li ionic liquids containing Li+ as the only cations because solvent-free fused Li salts do not polarise in electrochemical cells, owing to the absence of neutral solvents that allow polarisation in the salt concentration and the inevitably homogeneous density in the cells under anion-blocking conditions. However, we found that borate-based Li ionic liquids induce concentration polarisation in a Li/Li symmetric cell, which results in their transference (transport) numbers under anion-blocking conditions (tabcLi) being well below unity. The electrochemical polarisation of the borate-based Li ionic liquids was attributed to an equilibrium shift caused by exchangeable B-O coordination bonds in the anions to generate Li salts and borate-ester solvents at the electrode/electrolyte interface. By comparing borate-based Li ionic liquids containing different ligands, the B-O bond strength and extent of ligand exchange were found to be directly linked to the tabcLi values. This study confirms that the presence of dynamic exchangeable bonds causes electrochemical polarisation and provides a reference for the rational molecular design of Li ionic liquids aimed at achieving single-ion conducting liquid electrolytes.
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Affiliation(s)
- Keisuke Shigenobu
- Department of Chemistry and Life Science, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan.
| | - Frederik Philippi
- Department of Chemistry and Life Science, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan.
| | - Seiji Tsuzuki
- Institute of Advanced Sciences, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan
| | - Hisashi Kokubo
- Department of Chemistry and Life Science, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan.
| | - Kaoru Dokko
- Department of Chemistry and Life Science, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan. .,Institute of Advanced Sciences, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan
| | - Masayoshi Watanabe
- Institute of Advanced Sciences, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan
| | - Kazuhide Ueno
- Department of Chemistry and Life Science, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan. .,Institute of Advanced Sciences, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan
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Sudoh T, Shigenobu K, Dokko K, Watanabe M, Ueno K. Li + transference number and dynamic ion correlations in glyme-Li salt solvate ionic liquids diluted with molecular solvents. Phys Chem Chem Phys 2022; 24:14269-14276. [PMID: 35667383 DOI: 10.1039/d2cp01409b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Highly concentrated electrolytes (HCEs) have attracted significant interest as promising liquid electrolytes for next-generation Li secondary batteries, owing to various beneficial properties both in the bulk and at the electrode/electrolyte interface. One particular class of HCEs consists of binary mixtures of lithium bis(trifluoromethanesulfonyl)amide (LiTFSA) and oligoethers that behave like ionic liquids. [Li(G4)][TFSA], which comprises an equimolar mixture of LiTFSA and tetraglyme (G4), is an example. In our previous works, the addition of low-polarity molecular solvents to [Li(G4)][TFSA] was found to effectively enhance the conductivity while retaining the unique Li-ion solvation structure. However, it remains unclear how the diluents affect another key electrolyte parameter-the Li+ transference number-despite its critical importance for achieving the fast charging/discharging of Li secondary batteries. Thus, in this study, the effects of diluents on the extremely low Li+ transference number under anion-blocking conditions in [Li(G4)][TFSA] were elucidated, with a special focus on the polarity of the additional solvents. The concentration dependence of the dynamic ion correlations was further studied in the framework of the concentrated electrolyte theory. The results revealed that a non-coordinating diluent is not involved in the modification of the ion transport mechanism, and therefore the low Li+ transference number is inherited by the diluted electrolytes. In contrast, a coordinating diluent effectively reduces the anti-correlated ion motions of [Li(G4)][TFSA], thereby improving the Li+ transference number. This is the first time that the significant effects of the coordination properties of the diluting solvents on the dynamic ion correlations and Li+ transference numbers have been reported for diluted solvate ionic liquids.
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Affiliation(s)
- Taku Sudoh
- Department of Chemistry and Life Science, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan.
| | - Keisuke Shigenobu
- Department of Chemistry and Life Science, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan.
| | - Kaoru Dokko
- Department of Chemistry and Life Science, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan. .,Advanced Chemical Energy Research Centre (ACERC), Institute of Advanced Sciences, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan
| | - Masayoshi Watanabe
- Advanced Chemical Energy Research Centre (ACERC), Institute of Advanced Sciences, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan
| | - Kazuhide Ueno
- Department of Chemistry and Life Science, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan. .,Advanced Chemical Energy Research Centre (ACERC), Institute of Advanced Sciences, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan
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Ugata Y, Shigenobu K, Tatara R, Ueno K, Watanabe M, Dokko K. Solvate electrolytes for Li and Na batteries: structures, transport properties, and electrochemistry. Phys Chem Chem Phys 2021; 23:21419-21436. [PMID: 34550122 DOI: 10.1039/d1cp02946k] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Polar solvents dissolve Li and Na salts at high concentrations and are used as electrolyte solutions for batteries. The solvents interact strongly with the alkali metal cations to form complexes in the solution. The activity (concentration) of the uncoordinated solvent decreases as the salt concentration is increased. At extremely high salt concentrations, all the solvent molecules are involved in the coordination of the ions and form the solvates of the salts. In this article, we review the structures, transport properties, and electrochemistry of Li/Na salt solvates. In molten solvates, the activity of the uncoordinated solvent is negligible; this is the main origin of their peculiar characteristics, such as high thermal stability, wide electrochemical window, and unique ion transport. In addition, the solvent activity greatly influences the electrochemical reactions in Li/Na batteries. We highlight the attractive features of molten solvates as promising electrolytes for next-generation batteries.
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Affiliation(s)
- Yosuke Ugata
- Department of Chemistry and Life Science, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan.
| | - Keisuke Shigenobu
- Department of Chemistry and Life Science, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan.
| | - Ryoichi Tatara
- Department of Applied Chemistry, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku, Tokyo 162-8601, Japan.,Unit of Elements Strategy Initiative for Catalysts & Batteries (ESICB), Kyoto University, Kyoto 615-8510, Japan
| | - Kazuhide Ueno
- Department of Chemistry and Life Science, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan. .,Advanced Chemical Energy Research Center, Institute of Advanced Sciences, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan
| | - Masayoshi Watanabe
- Advanced Chemical Energy Research Center, Institute of Advanced Sciences, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan
| | - Kaoru Dokko
- Department of Chemistry and Life Science, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan. .,Unit of Elements Strategy Initiative for Catalysts & Batteries (ESICB), Kyoto University, Kyoto 615-8510, Japan.,Advanced Chemical Energy Research Center, Institute of Advanced Sciences, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan
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Mizuno H, Hashimoto K, Shigenobu K, Kokubo H, Ueno K, Watanabe M. Direct Observation of Photo‐Induced Reversible Sol–Gel Transition in Block Copolymer Self‐Assembly Containing an Azobenzene Ionic Liquid. Macromol Rapid Commun 2021. [DOI: 10.1002/marc.202170040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Mizuno H, Hashimoto K, Shigenobu K, Kokubo H, Ueno K, Watanabe M. Direct Observation of Photo-Induced Reversible Sol-Gel Transition in Block Copolymer Self-Assembly Containing an Azobenzene Ionic Liquid. Macromol Rapid Commun 2021; 42:e2100091. [PMID: 33851443 DOI: 10.1002/marc.202100091] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 03/23/2021] [Indexed: 01/05/2023]
Abstract
Using atomic force microscopy, the photo-induced reversible changes in a block copolymer self-assembly containing an azobenzene ionic liquid, which undergoes sol-gel transition is directly observed. This is the first report on the sol-gel transition of an ABA-type block copolymer consisting of upper critical solution temperature (UCST)-type A blocks in a photoresponsive ionic liquid mixture. The sol-gel transition is accompanied by an order-to-disorder structural change, which subsequently induces a change in the ionic conductivity. Surprisingly, the photo-induced ionic conductivity and rheological changes occurs rapidly (≈30 s) despite the dense (≈80 wt%) polymeric system. The rapid structural change is probably attributable to the fast diffusion of the ionic liquid.
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Affiliation(s)
- Haruna Mizuno
- Department of Chemistry and Life Science, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama, 240-8501, Japan
| | - Kei Hashimoto
- Institute of Advanced Sciences, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama, 240-8501, Japan
| | - Keisuke Shigenobu
- Department of Chemistry and Life Science, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama, 240-8501, Japan
| | - Hisashi Kokubo
- Department of Chemistry and Life Science, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama, 240-8501, Japan
| | - Kazuhide Ueno
- Department of Chemistry and Life Science, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama, 240-8501, Japan
| | - Masayoshi Watanabe
- Institute of Advanced Sciences, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama, 240-8501, Japan
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Shigenobu K, Shibata M, Dokko K, Watanabe M, Fujii K, Ueno K. Anion effects on Li ion transference number and dynamic ion correlations in glyme-Li salt equimolar mixtures. Phys Chem Chem Phys 2021; 23:2622-2629. [PMID: 33475115 DOI: 10.1039/d0cp06381a] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
To achieve single-ion conducting liquid electrolytes for the rapid charge and discharge of Li secondary batteries, improvement in the Li+ transference number of the electrolytes is integral. Few studies have established a feasible design for achieving Li+ transference numbers approaching unity in liquid electrolytes consisting of low-molecular-weight salts and solvents. Previously, we studied the effects of Li+-solvent interactions on the Li+ transference number in glyme- and sulfolane-based molten Li salt solvates and clarified the relationship between this transference number and correlated ion motions. In this study, to deepen our insight into the design principles of single-ion conducting liquid electrolytes, we focused on the effects of Li+-anion interactions on Li ion transport in glyme-Li salt equimolar mixtures with different counter anions. Interestingly, the equimolar triglyme (G3)-lithium trifluoroacetate (Li[TFA]) mixture ([Li(G3)][TFA]) demonstrated a high Li+ transference number, estimated via the potentiostatic polarization method (tPPLi = 0.90). Dynamic ion correlation studies suggested that the high tPPLi could be mainly ascribed to the strongly coupled Li+-anion motions in the electrolytes. Furthermore, high-energy X-ray total scattering measurements combined with all-atom molecular dynamics simulations showed that Li+ ions and [TFA] anions aggregated into ionic clusters with a relatively long-range ion-ordered structure. Therefore, the collective motions of the Li ions and anions in the form of highly aggregated ion clusters, which likely diminish rather than enhance ionic conductivity, play a significant role in achieving high tPPLi in liquid electrolytes. Based on the dynamic ion correlations, a potential design approach is discussed to accomplish single-ion conducting liquid electrolytes with high ionic conductivity.
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Affiliation(s)
- Keisuke Shigenobu
- Department of Chemistry and Life Science, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan.
| | - Masayuki Shibata
- Graduate School of Sciences and Technology for Innovation, Yamaguchi University, 2-16-1 Tokiwadai, Ube, Yamaguchi 755-8611, Japan.
| | - Kaoru Dokko
- Department of Chemistry and Life Science, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan. and Advanced Chemical Energy Research Centre (ACERC), Institute of Advanced Sciences, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan
| | - Masayoshi Watanabe
- Advanced Chemical Energy Research Centre (ACERC), Institute of Advanced Sciences, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan
| | - Kenta Fujii
- Graduate School of Sciences and Technology for Innovation, Yamaguchi University, 2-16-1 Tokiwadai, Ube, Yamaguchi 755-8611, Japan.
| | - Kazuhide Ueno
- Department of Chemistry and Life Science, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan. and Advanced Chemical Energy Research Centre (ACERC), Institute of Advanced Sciences, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan
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Shigenobu K, Dokko K, Watanabe M, Ueno K. Solvent effects on Li ion transference number and dynamic ion correlations in glyme- and sulfolane-based molten Li salt solvates. Phys Chem Chem Phys 2020; 22:15214-15221. [PMID: 32598420 DOI: 10.1039/d0cp02181d] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The Li+ transference number of electrolytes is one of the key factors contributing to the enhancement in the charge-discharge performance of Li secondary batteries. However, a design principle to achieve a high Li+ transference number has not been established for liquid electrolytes. To understand the factors governing the Li+ transference number tLi, we investigated the influence of the ion-solvent interactions, Li ion coordination, and correlations of ion motions on the Li+ transference number in glyme (Gn, n = 1-4)- and sulfolane (SL)-based molten Li salt solvate electrolytes with lithium bis(trifluoromethansulfonyl)amide (LiTFSA). For the 1 : 1 tetraglyme-LiTFSA molten complex, [Li(G4)][TFSA], the Li+ transference number estimated using the potentiostatic polarisation method (t = 0.028) was considerably lower than that estimated using the self-diffusion coefficient data with pulsed filed gradient (PFG)-NMR (t = 0.52). The dynamic ion correlations (i.e., cation-cation, anion-anion, and cation-anion cross-correlations) were determined from the experimental data on the basis of Roling and Bedrov's concentrated solution theory, and the results suggest that the strongly negative cross-correlations of the ion motions (especially for cation-cation motions) are responsible for the extremely low t of [Li(G4)][TFSA]. In contrast, t is larger than t in the SL-based electrolytes. The high t of the SL-based electrolytes was ascribed to the substantially weaker anti-correlations of cation-cation and cation-anion motions. Whereas the translational motions of the long-lived [Li(glyme)]+ and [TFSA]- dominate the ionic conduction for [Li(G4)][TFSA], Li ion hopping/exchange conduction was reported to be prevalent in the SL-based electrolytes. The unique Li ion conduction mechanism is considered to contribute to the less correlated cation-cation and cation-anion motions in SL-based electrolytes.
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Affiliation(s)
- Keisuke Shigenobu
- Department of Chemistry and Life Science, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan.
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Shao Y, Shigenobu K, Watanabe M, Zhang C. Role of Viscosity in Deviations from the Nernst-Einstein Relation. J Phys Chem B 2020; 124:4774-4780. [PMID: 32412758 PMCID: PMC7497660 DOI: 10.1021/acs.jpcb.0c02544] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Revised: 05/05/2020] [Indexed: 11/30/2022]
Abstract
Deviations from the Nernst-Einstein relation are commonly attributed to ion-ion correlation and ion pairing. Despite the fact that these deviations can be quantified by either experimental measurements or molecular dynamics simulations, there is no rule of thumb to tell the extent of deviations. Here, we show that deviations from the Nernst-Einstein relation are proportional to the inverse viscosity by exploring the finite-size effect on transport properties under periodic boundary conditions. This conclusion is in accord with the established experimental results of ionic liquids.
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Affiliation(s)
- Yunqi Shao
- Department
of Chemistry-Ångström Laboratory, Uppsala University, Lägerhyddsvägen 1, P.O. Box 538, 75121 Uppsala, Sweden
| | - Keisuke Shigenobu
- Department
of Chemistry and Biotechnology, Yokohama
National University, Yokohama 240-8501, Japan
| | - Masayoshi Watanabe
- Department
of Chemistry and Biotechnology, Yokohama
National University, Yokohama 240-8501, Japan
| | - Chao Zhang
- Department
of Chemistry-Ångström Laboratory, Uppsala University, Lägerhyddsvägen 1, P.O. Box 538, 75121 Uppsala, Sweden
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12
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Shigenobu K, Nakanishi A, Ueno K, Dokko K, Watanabe M. Glyme–Li salt equimolar molten solvates with iodide/triiodide redox anions. RSC Adv 2019; 9:22668-22675. [PMID: 35519483 PMCID: PMC9067099 DOI: 10.1039/c9ra03580j] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 07/19/2019] [Indexed: 01/02/2023] Open
Abstract
Room-temperature-fused Li salt solvates that exhibit ionic liquid-like behaviour can be formed using particular combinations of multidentate glymes and lithium salts bearing weakly coordinating anions, and are now deemed a subset of ionic liquids, viz. solvate ionic liquids (SILs). Herein, we report redox-active glyme–Li salt molten solvates consisting of tetraethyleneglycol ethylmethyl ether (G4Et) and lithium iodide/triiodide, [Li(G4Et)]I and [Li(G4Et)]I3. The coordination structure of the complex ions and the thermal, transport, and electrochemical properties of these molten Li salt solvates were investigated to diagnose whether they can be categorized as SILs. [Li(G4Et)]+ and I3− were found to remain stable as discrete ions and exist as well-dissociated forms in the liquid state, indicating that [Li(G4Et)]I3 can be classified as a good SIL. This study also clarified that the I− and I3− counter anions exhibit an electrochemical redox reaction in the highly concentrated molten Li salt solvates. The redox-active molten Li solvates were further studied as a highly concentrated catholyte for use in rechargeable semi-liquid lithium batteries. Although the cell constructed using [Li(G4Et)]I3 failed to charge after the initial discharge step, the cell containing [Li(G4Et)]I demonstrates reversible charge–discharge behaviour with a high volumetric energy density of 180 W h L−1 based on the catholyte volume. Redox-active glyme–Li salt equimolar molten solvates based on a I−/I3− couple could be employed as a highly concentrated catholyte for semi-liquid rechargeable lithium batteries.![]()
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Affiliation(s)
- Keisuke Shigenobu
- Department of Chemistry and Biotechnology
- Yokohama National University
- Yokohama 240-8501
- Japan
| | - Azusa Nakanishi
- Department of Chemistry and Biotechnology
- Yokohama National University
- Yokohama 240-8501
- Japan
| | - Kazuhide Ueno
- Department of Chemistry and Biotechnology
- Yokohama National University
- Yokohama 240-8501
- Japan
| | - Kaoru Dokko
- Department of Chemistry and Biotechnology
- Yokohama National University
- Yokohama 240-8501
- Japan
| | - Masayoshi Watanabe
- Department of Chemistry and Biotechnology
- Yokohama National University
- Yokohama 240-8501
- Japan
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13
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14
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Shinagawa S, Ikeda M, Nestor PJ, Shigenobu K, Fukuhara R, Nomura M, Hodges JR. Characteristics of abnormal eating behaviours in frontotemporal lobar degeneration: a cross-cultural survey. J Neurol Neurosurg Psychiatry 2009; 80:1413-4. [PMID: 19917828 DOI: 10.1136/jnnp.2008.165332] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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15
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Kamata K, Satoh T, Matsumoto T, Noguchi E, Taguchi K, Kobayashi T, Tanaka H, Shigenobu K. Enhancement of methoxamine-induced contractile responses of rat ventricular muscle in streptozotocin-induced diabetes is associated with alpha1A adrenoceptor upregulation. Acta Physiol (Oxf) 2006; 188:173-83. [PMID: 17054657 DOI: 10.1111/j.1748-1716.2006.01616.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
AIM To clarify the time-related changes in cardiac function and the mechanism underlying the cardiac dysfunction present in diabetes mellitus, we studied mechanical responses induced by alpha(1)- and beta-adrenoceptors, the Ca(2+)-entry promoter Bay K 8644- and ryanodine (an agent known to inhibit Ca(2+) release from the sarcoplasmic reticulum) in papillary muscles from streptozotocin (STZ)-induced diabetic and age-matched control rats. METHODS Male Wistar rats received a single injection of STZ (60 mg kg(-1)) via the tail vein to induce diabetes. For the mechanical studies, papillary muscle preparations were suspended in an organ bath and isometric contractions were measured in 1-, 4-, and 10-week STZ-induced diabetic and age-matched control rats. RESULTS In 1-week diabetic rats, the contractions induced by isoproterenol, methoxamine and Bay K 8644 were unchanged (vs. age-matched controls). In 4-week diabetic rats, (a) the isoproterenol- and Bay K 8644-induced contractions were impaired, (b) sensitivity to ryanodine was reduced, whereas (c) the methoxamine-induced contraction was unchanged. In 10-week diabetic rats, the isoproterenol- and Bay K 8644-induced contractile responses were impaired and the sensitivity to ryanodine was reduced, but in sharp contrast the methoxamine-induced contraction was enhanced. Both the mRNA level for the alpha(1A) adrenoceptor (but not the alpha(1B) or alpha(1D) mRNAs) and alpha(1A) adrenoceptor protein were increased in 10-week diabetic rats (vs. age-matched controls). CONCLUSION These results suggest that impairments of beta-adrenergic and Ca(2+)-handling mechanisms occur early in the development of cardiomyopathy in STZ-induced diabetic rats, and that this is followed by augmentation of alpha(1A) adrenoceptor-mediated inotropy due to alpha(1A) adrenoceptor upregulation.
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Affiliation(s)
- K Kamata
- Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University, Tokyo, Japan.
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16
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Ikeda M, Fukuhara R, Shigenobu K, Hokoishi K, Maki N, Nebu A, Komori K, Tanabe H. Dementia associated mental and behavioural disturbances in elderly people in the community: findings from the first Nakayama study. J Neurol Neurosurg Psychiatry 2004; 75:146-8. [PMID: 14707327 PMCID: PMC1757456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 03/16/2023]
Abstract
OBJECTIVE To determine the prevalence of mental and behavioural disturbances associated with dementia in elderly people living in the Japanese community of Nakayama. METHODS A door to door three phase population survey was carried out on all persons aged 65 years and older living at home. The study included a psychiatric interview, neurological and neuropsychological examination, and cranial computed tomography. Participants with dementia were rated on the neuropsychiatric inventory. RESULTS Of 1438 inhabitants, 1162 (81.0%) completed the protocol. The prevalence of dementia was 4.8%. Of the 60 participants with dementia (Alzheimer's disease 35%, vascular dementia 47%, and dementia from other causes 17%), 53 (88.3%) had shown one or more mental and behavioural disturbances. Apathy/indifference (56.7%), followed by agitation/aggression (35%), aberrant motor behaviour (31.7%), and irritability (31.7%) were the common symptoms. More productive (positive) symptoms such as delusions and aberrant motor behaviour were found in the Alzheimer group than in the vascular dementia group. CONCLUSIONS A wide range of dementia associated mental and behavioural disturbances developed in the majority of community dwelling individuals with dementia. The findings suggest that a screening programme focusing on identifying these symptoms should be included in the physician's diagnostic tools for dementia.
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Affiliation(s)
- M Ikeda
- Department of Neuropsychiatry, Ehime University School of Medicine, Ehime, Japan.
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17
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Imai T, Tanaka Y, Okamoto T, Yamamoto Y, Horinouchi T, Tanaka H, Koike K, Shigenobu K. Evidence that action potential generation is not the exclusive determinant to trigger spontaneous myogenic contraction of guinea-pig urinary bladder smooth muscle. Acta Physiol Scand 2002; 176:57-63. [PMID: 12193219 DOI: 10.1046/j.1365-201x.2002.01009.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Urinary bladder smooth muscle (UBSM) exhibits spontaneous contraction. This spontaneous mechanical activity is myogenic and can be closely related to the UBSM cell action potential to facilitate Ca2+ influx through voltage-gated Ca2+ channels. In the present study, to know whether this membrane electrical event is the exclusive mechanism to trigger spontaneous smooth muscle contraction, we compared the inhibitory effects of Ca2+ channel blockers on the spontaneous action potential and mechanical activity in the isolated guinea-pig UBSM. Both action potential and rhythmic contraction were generated spontaneously in the presence of atropine (1 microM), phentolamine (1 microM), propranolol (1 microM), suramin (10 microM) and tetrodotoxin (1 microM), which suggest that both phenomena were myogenic in origin. Nisoldipine (100 nM) and diltiazem (10 microM) completely eliminated the generation of action potential whereas its frequency was dramatically increased by a dihydropyridine Ca2+ agonist, BayK 8644 (1 microM). In contrast to disappearance of action potential in the presence of Ca2+ channel blockers, spontaneous contraction of UBSM was inhibited only partly by nisoldipine or diltiazem and most of the mechanical components persisted in these channel blockers. These results indicate that spontaneous action potential in UBSM cell is generated through the activation of L-type voltage-gated Ca2+ channels. The subsequent elevation of intracellular Ca2+ concentrations during a burst of action potentials can be partly responsible for the induction of UBSM mechanical activity. In addition, the present study provides evidence that UBSM spontaneous mechanical activity is also attributable to the mechanism(s) other than the generation of Ca2+ spike.
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Affiliation(s)
- T Imai
- Department of Pharmacology, Toho University School of Pharmaceutical Sciences, Miyama, Funabashi-City, Chiba, Japan
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18
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Tanaka Y, Shigenobu K. A review of HNS-32: a novel azulene-1-carboxamidine derivative with multiple cardiovascular protective actions. Cardiovasc Drug Rev 2002; 19:297-312. [PMID: 11830749 DOI: 10.1111/j.1527-3466.2001.tb00072.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
HNS-32 [N(1),N(1)-dimethyl-N(2)-(2-pyridylmethyl)-5-isopropyl-3,8-dimethylazulene-1- carboxamidine] (CAS Registry Number: 186086-10-2) is a newly synthesized azulene derivative. Computer simulation showed that its three dimensional structure is similar to that of the class Ib antiarrhythmic drugs, e.g., lidocaine or mexiletine. HNS-32 potently suppressed ventricular arrhythmias induced by ischemia due to coronary ligation and/or ischemia-reperfusion in dogs and rats. In the isolated dog and guinea pig cardiac tissues, HNS-32 had negative inotropic and chronotropic actions, prolonged atrial-His and His-ventricular conduction time and increased coronary blood flow. In the isolated guinea pig ventricular papillary muscle, HNS-32 decreased maximal rate of action potential upstroke (Vmax) and shortened action potential duration (APD). These findings suggest that HNS-32 inhibits inward Na+ and Ca2+ channel currents. In the isolated pig coronary and rabbit conduit arteries, HNS-32 inhibited both Ca2+ channel-dependent and -independent contractions induced by a wide variety of chemical stimuli. HNS-32 is a potent inhibitor of protein kinase C (PKC)-mediated constriction of cerebral arteries. It is likely to block both, Na+ and Ca2+ channels expressed in cardiac and vascular smooth muscles. These multiple ion channel blocking effects are largely responsible for the antiarrhythmic and vasorelaxant actions of HNS-32. This drug may represent a novel approach to the treatment of arrhythmias.
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Affiliation(s)
- Y Tanaka
- Department of Pharmacology, Toho University School of Pharmaceutical Sciences, 2-2-1 Miyama, Funabashi-City, Chiba 274-8510, Japan.
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19
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Noguchi K, Saitoh M, Nakazawa T, Tanaka H, Tanaka Y, Shigenobu K. Cerebral artery selective inhibition of protein kinase c-mediated contraction by hns-32, a novel azulene-1-carboxamidine derivative. Res Commun Mol Pathol Pharmacol 2002; 107:45-54. [PMID: 11334370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
The vasorelaxant actions of a novel azulene-1-carboxamidine derivative, HNS-32, were investigated on the tension development evoked by phorbol 12, 13 dibutyrate (PDBu) in cerebral and femoral arteries isolated from the dogs. In basilar artery, HNS-32 inhibited almost completely PDBu-induced contraction in a concentration-dependent manner with potency about 10 times stronger than that of fasudil, a protein kinase inhibitor. In contrast, in femoral artery, HNS-32 failed to suppress the tension development in response to PDBu whereas fasudil inhibited it with a similar potency as in basilar artery. These findings indicate that HNS-32 selectively suppresses cerebral artery contraction mediated via an activation of protein kinase C.
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Affiliation(s)
- K Noguchi
- Pharmacology Laboratory, Pharmaceutical Research Laboratories, Taisho Pharmaceutical Co., Ltd., Saitama, Japan.
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20
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Tanaka H, Masumiya H, Sekine T, Kase J, Kawanishi T, Hayakawa T, Miyata S, Sato Y, Nakamura R, Shigenobu K. Involvement of Ca2+ waves in excitation-contraction coupling of rat atrial cardiomyocytes. Life Sci 2001; 70:715-26. [PMID: 11833720 DOI: 10.1016/s0024-3205(01)01436-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Two-dimensional and line-scan analyses of the early phase Ca2+ transients in rat cardiomyocytes were performed with a rapid-scanning laser confocal microscope and fluo-3 to elucidate the mechanism of activation of Ca2+ release from the sarcoplasmic reticulum in atrial myocytes which lack a well developed T-tubular network. On electrical stimulation of ventricular myocytes, Ca2+ concentration began to rise earliest at the Z-line level and became uniform throughout the cytoplasm within about 10 msec. In contrast, on stimulation of atrial myocytes, the earliest rise in Ca2+ occurred at the cell periphery and then spread to the cell interior; cytoplasmic Ca2+ became uniform after more than 30msec. The velocity of the propagation of rise in Ca2+ was 112 +/- 5.1 microm/sec (n = 10), which was similar to that of spontaneous Ca2+ waves observed in atrial and ventricular myocytes. No difference in frequency, amplitude and kinetics of spontaneous Ca2+ sparks was observed between the subsarcolemmal and central regions of atrial myocytes. Ryanodine concentration-dependently decreased the contractile force of isolated rat atrial and ventricular tissue preparations; the sensitivity was higher in atrial myocytes. The present study visualized the involvement of a propagated Ca2+-induced-Ca+ release mechanism in atrial but not ventricular myocytes. This difference may underlie some of the atrioventricular difference in response to physiological and pharmacological stimuli.
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Affiliation(s)
- H Tanaka
- Department of Pharmacology, Toho University School of Pharmaceutical Sciences, Chiba, Japan
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21
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Ono K, Masumiya H, Sakamoto A, Christé G, Shijuku T, Tanaka H, Shigenobu K, Ozaki Y. Electrophysiological analysis of the negative chronotropic effect of endothelin-1 in rabbit sinoatrial node cells. J Physiol 2001; 537:467-88. [PMID: 11731579 PMCID: PMC2278974 DOI: 10.1111/j.1469-7793.2001.00467.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
1. Electrophysiological effects of endothelin-1 (ET-1) were studied in rabbit sinoatrial node (SAN) using conventional microelectrode and whole-cell voltage and current recordings. 2. In rabbit SAN, RT-PCR detected ET(A) endothelin receptor mRNA. ET-1 (100 nM) increased the cycle length of action potentials (APs) from 305 +/- 15 to 388 +/- 25 ms; this effect was antagonised by the ET(A) receptor-selective antagonist BQ-123 (1 microM). ET-1 increased AP duration (APD50) by 22%, depolarised the maximum diastolic potential (MDP) from -59 +/- 1 to -53 +/- 2 mV, shifted the take-off potential by +5 mV and decreased the pacemaker potential (PMP) slope by 15%. Under exactly the same experimental conditions, ET-1 caused a positive chronotropic effect in guinea-pig SAN with a decrease of 13% in APD50, a shift of -4 mV in the take-off potential and an increase of 8% in the PMP slope. 3. Rabbit SAN exhibited two major cell types, distinguished both by their appearances and by their electrophysiological responses to ET-1. Whereas the spontaneous pacing rate and the PMP slope were similarly decreased by ET-1 (10 nM) in both cell types, ET-1 depolarised MDP from -67 +/- 1 to -62 +/- 4 mV in spindle-shaped cells but hyperpolarised it from -73 +/- 1 to -81 +/- 3 mV in rod-shaped cells. ET-1 decreased APD50 by 8 and 52% and shifted the take-off potential by +5 and -9 mV in spindle- and rod-shaped cells, respectively. 4. ET-1 decreased the high-threshold calcium current (I(CaL)) by about 50% in both cell types, without affecting its voltage dependence, and decreased the delayed rectifier K+ current (I(K)) with significant shifts (of +4.7 and +14.0 mV in spindle- and rod-shaped cells, respectively) in its voltage dependence. It was exclusively in rod-shaped cells that ET-1 activated a sizeable amount of time-independent inward-rectifying current. 5. The hyperpolarisation-activated current (I(f)), observed exclusively in spindle-shaped cells, was significantly increased by ET-1 at membrane potentials between -74.7 and -84.7 mV whereas it was significantly decreased at more negative potentials. ET-1 significantly decreased the slope of the current-voltage (I-V) relation of the I(f) tail without changing its half-maximum voltage. 6. The overall negative chronotropic influence of ET-1 on the whole rabbit SAN is interpreted as resulting from the integration of its different actions on spindle- and rod-shaped SAN cells through electrotonic interaction.
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Affiliation(s)
- K Ono
- Division of Chemical Pharmacology and Phytochemistry, National Institute of Health Sciences, 1-18-1 Kami-Yohga, Setagaya-ku, Tokyo 158-8501, Japan.
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22
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Yamaki F, Kaga M, Horinouchi T, Tanaka H, Koike K, Shigenobu K, Toro L, Tanaka Y. MaxiK channel-mediated relaxation of guinea-pig aorta following stimulation of IP receptor with beraprost via cyclic AMP-dependent and -independent mechanisms. Naunyn Schmiedebergs Arch Pharmacol 2001; 364:538-50. [PMID: 11770009 DOI: 10.1007/s002100100485] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The present study was aimed to elucidate the cellular pathway(s) controlling vascular relaxation triggered by stimulation of prostaglandin I2 (PGI2, IP) receptor with a stable PGI2 analog, beraprost. Beraprost caused a concentration-dependent relaxation in de-endothelialized guinea-pig aorta contracted with prostaglandin F2alpha (PGF2alpha). Beraprost-induced relaxation was almost abolished in high-KCl-contracted tissue, indicating a major role of K+ conductances. In contrast to other PGI2 analogs (e.g. cicaprost and iloprost), beraprost-induced relaxation was practically abolished by a selective voltage and Ca2+-activated K+ (MaxiK, BK) channel blocker Iberiotoxin (10(-7) M) or by tetraethylammonium (2 x 10(-3) M). The relaxation induced by beraprost was not significantly affected by other K+ channel blockers glibenclamide (10(-6) M) or Ba2+ (10(-5) M), but was slightly attenuated by 4-aminopyridine (10(-4) M). Beraprost increased intracellular cyclic AMP levels, suggesting a role for cyclic AMP-dependent pathways. A selective inhibitor of cyclic AMP-specific phosphodiesterase, RO-20-1724 (10(-4) M), significantly potentiated beraprost-induced relaxation. Iberiotoxin (10(-7) M) completely counteracted this potentiation. Moreover, tension decrement due to forskolin (3 x 10(-7) M) or 8-bromo-cyclic AMP (10(-2) M) was thoroughly restored by Iberiotoxin (10(-7) M), confirming a role for a cyclic AMP-dependent mechanism. However, SQ 22,536 (10(-4) M), an adenylyl cyclase inhibitor, did not affect beraprost-induced relaxation though it almost totally inhibited the elevation of cyclic AMP contents induced by beraprost, suggesting the existence of an additional mechanism that is cyclic AMP-independent. Moreover, cholera toxin (CTX, 1 microg/ml for 6 h), which activates the stimulatory G protein of adenylyl cyclase (Gs), significantly suppressed PGF2alpha-induced contraction both in the absence and presence of SQ 22,536 (10(-4) M). Iberiotoxin (10(-7) M) was also capable of restoring the relaxation induced by CTX. These findings suggest that MaxiK channel plays a primary role in mediating smooth muscle relaxation following stimulation of IP receptor with beraprost in guinea-pig aorta. Both cyclic AMP-dependent and -independent pathways contribute to the MaxiK channel-mediated relaxation following IP receptor stimulation in this vascular tissue. Direct regulation of MaxiK channels by Gs may partly account for the cyclic AMP-independent relaxant mechanism.
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MESH Headings
- 8-Bromo Cyclic Adenosine Monophosphate/pharmacology
- Adenine/analogs & derivatives
- Adenine/pharmacology
- Adenylyl Cyclase Inhibitors
- Animals
- Aorta, Thoracic/drug effects
- Aorta, Thoracic/physiology
- Cholera Toxin/pharmacology
- Colforsin/pharmacology
- Cyclic AMP/antagonists & inhibitors
- Cyclic AMP/biosynthesis
- Cyclic AMP/physiology
- Dose-Response Relationship, Drug
- Epoprostenol/analogs & derivatives
- Epoprostenol/pharmacology
- Female
- GTP-Binding Protein alpha Subunits, Gs/metabolism
- Guinea Pigs
- Large-Conductance Calcium-Activated Potassium Channels
- Male
- Potassium Channel Blockers/pharmacology
- Potassium Channels, Calcium-Activated/antagonists & inhibitors
- Potassium Channels, Calcium-Activated/metabolism
- Potassium Channels, Calcium-Activated/physiology
- Receptors, Epoprostenol
- Receptors, Prostaglandin/agonists
- Receptors, Prostaglandin/physiology
- Signal Transduction/drug effects
- Signal Transduction/physiology
- Vasodilation/drug effects
- Vasodilation/physiology
- Vasodilator Agents/pharmacology
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Affiliation(s)
- F Yamaki
- Department of Pharmacology, Toho University School of Pharmaceutical Sciences, Funabashi-City, Chiba, Japan
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23
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Imai T, Okamoto T, Yamamoto Y, Tanaka H, Koike K, Shigenobu K, Tanaka Y. Effects of different types of K+ channel modulators on the spontaneous myogenic contraction of guinea-pig urinary bladder smooth muscle. Acta Physiol Scand 2001; 173:323-33. [PMID: 11736694 DOI: 10.1046/j.1365-201x.2001.00908.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In the present study, effects of different types of K+ channel modulators on the spontaneous rhythmic contractile activity were examined in guinea-pig urinary bladder smooth muscle (UBSM). Guinea-pig UBSM exhibited myogenic rhythmic contraction in the presence of atropine (1 microM), phentolamine (1 microM), propranolol (1 microM), suramin (10 microM) and tetrodotoxin (1 microM). Nisoldipine (100 nM) or diltiazem (10 microM) substantially diminished UBSM contractile activity. Nisoldipine-resistant component of UBSM rhythmic contraction was further inhibited by gadolinium (200 microM). Iberiotoxin (50 nM), a selective blocker of large-conductance, voltage-gated Ca2+-activated K+ (K(Ca)) (BK) channel, dramatically increased both contraction amplitude and frequency whereas NS-1619 (30 microM), which increases BK channel activity, decreased them. Apamin (100 nM), a selective blocker of small-conductance, K(Ca) (SK) channel, increased contraction amplitude but decreased frequency. A blocker of voltage-gated K+ (Kv) channel, 4-aminopyridine (100 microM), significantly increased contraction frequency. E-4031, a blocker of a novel inwardly rectifying K+ channel, i.e. the human ether-a-go-go-related gene (HERG) K+ channel, significantly increased contraction amplitude. Glibenclamide (1-10 microM) (K(ATP) channel blocker) and Ba2+ (10 microM) (conventional K(ir) channel blocker) did not exhibit conspicuous effects on spontaneous contractile activity of UBSM. These findings imply that two types of K(Ca) (BK and SK) channels have prominent roles as negative feedback elements to limit extracellular Ca2+ influx-mediated guinea-pig UBSM contraction by regulating both amplitude and frequency. It was also suggested that both non-K(Ca) type of K+ (Kv and HERG-like K+) channels may contribute to the regulation of UBSM myogenic rhythmic contraction.
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Affiliation(s)
- T Imai
- Department of Pharmacology, Toho University School of Pharmaceutical Sciences, Miyama, Funabashi-City, Chiba, Japan
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24
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Abstract
Frontotemporal lobar degeneration is the most common form of cortical dementia occurring in the presenium after Alzheimer's disease. We analyzed two types of frontotemporal dementia (FTD) and semantic dementia (SD) selected from a consecutive series of outpatients based on neuropsychological symptoms, psychiatric symptoms and abnormal behavior. In our series of 134 patients with primary degenerative dementia, there were 16 cases of FTD and 6 cases of SD. Patients with subgroups of FTD and patients with SD were distinguishable only by the presence of aphasia in the latter group. They were not distinguishable from one another by other neuropsychological examinations, behavioral abnormalities or psychiatric symptoms assessed with the Neuropsychiatric Inventory.
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Affiliation(s)
- K Hokoishi
- Department of Neuropsychiatry, Ehime University School of Medicine, Shigenobu-chou, Onsen-gun, Ehime 791-0295, Japan
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Ikeda M, Hokoishi K, Maki N, Nebu A, Tachibana N, Komori K, Shigenobu K, Fukuhara R, Tanabe H. Increased prevalence of vascular dementia in Japan: a community-based epidemiological study. Neurology 2001; 57:839-44. [PMID: 11552014 DOI: 10.1212/wnl.57.5.839] [Citation(s) in RCA: 135] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND AND OBJECTIVE It has been suggested that there is a major difference in the ratio of AD to vascular dementia (VaD) between Japan and Western countries. To determine the type-specific prevalence of dementia in community-dwelling elderly from the Japanese community of Nakayama, all patients with dementing illness underwent a CT scan. METHODS A door-to-door three-phase population survey was carried out on all persons aged 65 years and older residing at home on the prevalence day (January 1, 1997). The ascertainment of cases was made between January 1997 and March 1998. The study included a psychiatric interview; physical, neurologic, and neuropsychologic examinations; comprehensive laboratory tests; and cranial CT. A public health nurse also interviewed a person close to each subject. Dementia was defined according to the Diagnostic and Statistical Manual of Mental Disorders, third edition-revised, criteria, AD according to the National Institute of Neurological and Communicative Disorders and Stroke-Alzheimer's Disease and Related Disorders Association, and VaD according to Diagnostic and Statistical Manual of Mental Disorders, fourth edition, combined with information from the patient's neurologic history and CT scanning. RESULTS Of 1438 inhabitants, 1162 (81.0%) completed the protocol. The prevalence of dementia was 4.8%. Of the 60 subjects with dementia, 35% had AD, 47% had VaD, and 17% had dementia resulting from other causes. CONCLUSIONS The prevalence of dementia was similar to previous reports, but, contrary to results of virtually all studies conducted in developed countries and those recently conducted in Japan, almost half of the cases in the present study appeared to have VaD with neuroradiologic confirmation.
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Affiliation(s)
- M Ikeda
- Department of Neuropsychiatry, Ehime University School of Medicine, Japan.
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Nebu A, Ikeda M, Fukuhara R, Shigenobu K, Maki N, Hokoishi K, Komori K, Yasuoka T, Tanabe H. Relationship between blood flow kinetics and severity of Alzheimer's disease: assessment of severity using a questionnaire-type examination, Alzheimer's disease assessment scale, cognitive sub-scale (ADAS(cog)). Dement Geriatr Cogn Disord 2001; 12:318-25. [PMID: 11455133 DOI: 10.1159/000051277] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
We assessed hemokinetics associated with changes in Alzheimer's disease (AD) severity in 90 AD patients by researching the relationship between AD Assessment Scale, cognitive sub-scale (ADAS(cog)) scores and regional cerebral blood flow (rCBF). In the present study, we employed the questionnaire-type ADAS(cog) examination to accurately assess the severity of AD. Between five groups classified on the basis of ADAS(cog) score, significant differences were observed in parietal, lateral temporal and superior frontal rCBF. In addition, in parietal and lateral temporal regions, significant correlations were also observed between ADAS(cog) score and rCBF. In superior frontal rCBF, significant differences were noted only between group 5 (> or =40 ADAS(cog) points) and each of the other groups; there was no significant correlation between rCBF and ADAS(cog) score. Thus, we propose the following mechanism for blood flow kinetics associated with changed severity: In an early stage of AD, blood flow in the medial temporal cortex is impaired, and gradually involves the temporoparietal regions. While the medial temporal impairment of blood flow reaches a plateau, temporoparietal blood flow continues to be impaired well into a severe stage, at which point blood flow impairment in the frontal region is initiated.
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Affiliation(s)
- A Nebu
- Department of Neuropsychiatry, Ehime University School of Medicine, Shigenobu-chou, Onsen-gun, Ehime 791-0295, Japan
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Fukuhara R, Ikeda M, Nebu A, Kikuchi T, Maki N, Hokoishi K, Shigenobu K, Komori K, Tanabe H. Alteration of rCBF in Alzheimer's disease patients with delusions of theft. Neuroreport 2001; 12:2473-6. [PMID: 11496132 DOI: 10.1097/00001756-200108080-00037] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
We investigated the neural substrate of the delusion of theft in patients with Alzheimer's disease (AD). Nine AD patients with only one type of delusion (delusions of theft) and nine age, cognitive function-matched AD patients without any type of delusions were selected from 334 consecutive outpatients of Ehime University Hospital. All subjects underwent (99m)Tc-HMPAO SPECT scanning, and SPECT images were analyzed by Statistical Parametric Mapping (SPM). AD patients with delusions of theft showed significant hypoperfusion in the right medial posterior parietal region compared to patients without delusions. Our data suggest that attention impairment or lack of awareness of illness caused by right parietal dysfunction might play a role in producing the delusion of theft.
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Affiliation(s)
- R Fukuhara
- Department of Neuropsychiatry, Ehime University School of Medicine, Shigenobu-chou, Onsen-gun, Ehime 791-0295, Japan
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Naito A, Hasegawa H, Kurasawa T, Ohtake Y, Matsukawa H, Ezure Y, Koike K, Shigenobu K. Histopathological study of kidney abnormalities in an experimental SIADH rat model and its application to the evaluation of the pharmacologic profile of VP-343, a selective vasopressin V2 receptor antagonist. Biol Pharm Bull 2001; 24:897-901. [PMID: 11510481 DOI: 10.1248/bpb.24.897] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The aim of this work was to investigate histopathologically the relationship between the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) and kidney abnormalities and the therapeutic efficacy of VP-343 ((N-[4-[[(2S,3aR)-2-hydroxy-2,3,3a,4-tetrahydropyrrolo[1,2-alqunoxalin-5(1H)-yl]phenyl]-4'-methyl[1,1'-biphenyl]-2-carboxamide], a selective vasopressin V2 receptor antagonist, in an experimental SIADH rat model. In the model, which was prepared by continuously administering 1-desamino-8-D-arginine vasopressin (DDAVP), histopathologic abnormalities, such as dilatation of tubules, basophilic changes in tubules, inflammatory cell infiltration, and mineralization were found in the kidney, accompanied by significant increases in the relative weight of the kidney, lung, liver, adrenal gland, and heart. VP-343 was shown to be effective in protecting the kidney from the histopathologic abnormalities and to normalize the relative weight of the kidney and several common pathophysiologic features, such as hyponatremia, hyposmolarity of plasma, hyperosmolarity of urea, and oligurea, as described previously. These results demonstrate the occurrence of histopathologic abnormalities in the kidney and the efficacy of VP-343 in improving abnormalities in the DDAVP-induced SIADH rat model.
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Affiliation(s)
- A Naito
- Sagami Research Laboratory, Wakamoto Pharmaceutical Co., Ltd., Kanagawa, Japan.
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Tanaka Y, Shigenobu K, Nakayama K. Effects of endothelin-1 on the myogenic contraction of canine cerebral artery in response to quick stretch. Res Commun Mol Pathol Pharmacol 2001; 109:95-101. [PMID: 11458989] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
Abstract
The present study was performed to investigate the effects of endothelin-1 (ET-1) on the myogenic contraction in response to mechanical stimulation in cerebral artery. Quick stretch at a rate of 10 cm/sec with the amount of 10 - 40% of the initial muscle length (=100%) produced a myogenic contraction in canine cerebral artery. ET-1 at 30 pM, which itself produces a small contraction corresponding to about 15% of the maximal response, potentiated stretch-induced contraction. By contrast, ET-1 at concentrations over 100 pM suppressed the stretch-induced tone. The potentiated component of stretch-induced tone in the presence of 30 pM ET-1 was largely attenuated by Ca2+ channel blockers, nimodipine (1 microM) or diltiazem (1 microM). These findings suggest that lower concentrations (pM range) of ET- 1 potentiates myogenic tension development of cerebral artery in response to mechanical stretch possibly via an increased Ca2+ influx through voltage-gated Ca2+ channel.
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Affiliation(s)
- Y Tanaka
- Department of Pharmacology, Toho University School of Pharmaceutical Sciences, Funabashi-City, Chiba, Japan.
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Kanayama M, Hashimoto T, Shigenobu K, Harada M, Oha F, Ohkoshi Y, Tada H, Yamamoto K, Yamane S. Adjacent-segment morbidity after Graf ligamentoplasty compared with posterolateral lumbar fusion. J Neurosurg 2001; 95:5-10. [PMID: 11453431 DOI: 10.3171/spi.2001.95.1.0005] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECT Of concern to spine surgeons are accelerated degenerative changes of motion segments located above and below where spinal fusion has been performed. Graf artificial ligament stabilization has been developed to avoid the adverse effect of spinal fusion. The object of this study was to assess the adjacent-segment morbidity of Graf ligamentoplasty compared with posterolateral fusion (PF) in which instrumentation was used. METHODS Data obtained in 45 patients who underwent L4-5 Graf ligamentoplasty (18 patients) or PF with instrumentation (27 patients) were reviewed retrospectively. The minimum follow-up period was 5 years. In the PF group a solid fusion rate of 92.6% was achieved. Radiographic evaluation included assessment of lumbar sagittal alignment, range of motion (ROM), and adjacent-disc degeneration. Adjacent-segment morbidity was clinically assessed by determining the reoperation rate. Graf ligamentoplasty maintained regional lordosis and flexibility (13 degrees in L4-5 lordosis; 4.4 degrees in L4-5 ROM). Although there was no difference in preoperative adjacent-disc condition between the two groups, radiographic evidence of adjacent-disc deterioration was observed more frequently in patients in the PF group than the Graf group (25% and 6% at L1-2; 38% and 6% at L2-3; 38% and 18% at L3-4; and 43% and 18% at L5-sacrum, respectively). One case in the Graf group (5.6%) and five cases in the PF group (18.5%) required additional surgeries for adjacent-segment lesions. CONCLUSIONS Graf ligamentoplasty cannot completely replace spinal fusion. In a well-selected group of patients, however, it was shown to maintain lumbar mobility and sagittal alignment, and it decreased the risk of adjacent-segment deterioration compared with PF with instrumentation.
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Affiliation(s)
- M Kanayama
- Department of Orthopaedic Surgery, Hakodate Central General Hospital, Hokkaido, Japan.
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31
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Hashimoto T, Oha F, Shigenobu K, Kanayama M, Harada M, Ohkoshi Y, Tada H, Yamamoto K, Yamane S. Mid-term clinical results of Graf stabilization for lumbar degenerative pathologies. a minimum 2-year follow-up. Spine J 2001; 1:283-9. [PMID: 14588333 DOI: 10.1016/s1529-9430(01)00028-6] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
BACKGROUND CONTEXT Spinal fusion has some adverse effects, such as nonunion and pain at the site of grafted bone, and fusion with rigid spinal instrumentation especially may have the possibility of increasing mechanical stress on the segments adjacent to the site of fusion. The theory of the Graf system is that it will decrease adjacent disc deterioration because of maintenance of regional lordosis with flexibility and restriction of the motion of unstable segments without rigid spinal fusion. PURPOSE To assess the clinical and radiologic results of Graf stabilization for lumbar degenerative disorders with minimal or mild instability. STUDY DESIGN This is a retrospective study examining the mid-term results of Graf stabilization. PATIENT SAMPLE In total, 59 patients underwent Graf ligamentoplasty and adequate decompression from April 1993 to September 1997. The subjects were 30 men and 29 women, and the mean age at the time of surgery was 60.6 years, ranging from 23 to 82 years. The average follow-up period was 3 years and 5 months, ranging from 2 years to 5 years and 10 months. OUTCOME MEASURES We evaluated the surgical results using a scoring system, a visual analog scale, and radiological measurements. METHODS The results were assessed according to a clinical scoring system established by the Japanese Orthopaedic Association (JOA score) and ratings based on a visual analog scale. Through analysis of x-ray images, the sagittal alignment (regional lordosis) and the range of motion (ROM) of the stabilized segments were measured in all cases, and the percentage of segments slipping and posterior disc height were determined for 29 patients with degenerative spondylolisthesis. RESULTS Clinical scores and low back pain ratings based on a visual analog scale were significantly improved at the time of final follow-up compared with the preoperative values. Regional alignment of the operative segments was maintained in lordosis at the time of final follow-up. Preoperative ROM was significantly reduced at the time of final follow-up. There were no statistical differences in percentage of slippage or percentage of posterior disc height between the final follow-up values and the preoperative values. CONCLUSIONS Our clinical results indicate that the Graf system is a suitable treatment option for mild and early lumbar degenerative diseases with minimum flexion instability of less than 10 degrees.
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Affiliation(s)
- T Hashimoto
- Department of Orthopaedic Surgery, Hakodate Central General Hospital, Honcho 33-2, Hakodate City, Hokkaido 040-8585, Japan.
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Tanaka H, Shigenobu K. [Pharmaceutical agents for calcium-induced cell damage (T-type calcium channel antagonist)]. Clin Calcium 2001; 11:777-783. [PMID: 15775583] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
T-type Ca(2+) channels have properties distinct from the L-type and are involved in cardiac pacemaking and blood flow. Novel drugs with action on both L-type and T-type Ca(2+) channels, such as efonidipine, has been shown to optimize blood pressure and heart rate with minimum effect on myocardial contraction. Further studies on their organ-protective effects are now in progress.
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Affiliation(s)
- H Tanaka
- Department of Pharmacology, Toho University School of Pharmaceutical Sciences
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Tanaka H, Nishimaru K, Kobayashi M, Matsuda T, Tanaka Y, Shigenobu K. Acetylcholine-induced positive inotropy mediated by prostaglandin released from endocardial endothelium in mouse left atrium. Naunyn Schmiedebergs Arch Pharmacol 2001; 363:577-82. [PMID: 11383720 DOI: 10.1007/s002100100411] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The possible involvement of the endocardial endothelium in the positive inotropic response of the mouse left atrium to acetylcholine was examined pharmacologically. In mouse left atria, acetylcholine produced a biphasic inotropic response: a transient decrease in contractile force followed by a late increase. The positive response was not affected by the presence of phentolamine and propranolol, but was almost abolished by pretreatment of the preparation with 1% Triton X-100, which denudes the endocardium of its endothelium. Nordihydroguaiaretic acid, NG-nitro-L-arginine, BQ-123 and BQ-788 had no effect on the inotropic responses to acetylcholine, but indomethacin completely abolished the positive response. Prostaglandins and their analogues had a positive inotropic effect with a potency order PGF2alpha>PGD2>PGE2>U46619, whereas beraprost had no effect. Neither Triton X-100 pretreatment nor the presence of indomethacin affected the positive inotropic effect of PGF2alpha. Acetylcholine and PGF2alpha prolonged the action potential duration similarly. These results suggest that the acetylcholine-induced positive inotropic response in mouse left atria is mediated by prostaglandin released from the endocardial endothelium.
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Affiliation(s)
- H Tanaka
- Department of Pharmacology, Toho University School of Pharmaceutical Sciences, Funabashi, Chiba, Japan.
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Nakahara T, Moriuchi H, Tanaka Y, Yunoki M, Kubota Y, Sakamato K, Shigenobu K, Ishii K. Role of K+ channels in N-acetylprocainamide-induced relaxation of bovine tracheal smooth muscle. Eur J Pharmacol 2001; 415:73-8. [PMID: 11245854 DOI: 10.1016/s0014-2999(01)00796-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
We examined the relaxant effects of N-acetylprocainamide, the major hepatic metabolite of procainamide, on bovine tracheal smooth muscle, focusing on the possible involvement of K+ channels. N-acetylprocainamide produced a concentration-dependent and full inhibition of the tension development elicited by methacholine (0.3 or 1 microM). The potency of N-acetylprocainamide in diminishing methacholine-elicited tension development was one-half of that of procainamide. By comparison, N-acetylprocainamide inhibited high-K+ (40 mM)-induced contraction more potently than procainamide though both inhibitions were largely reduced when compared to those against methacholine-induced contraction. Iberiotoxin (30 nM), Ba(2+) (1 mM) or a combination of both agents significantly attenuated the relaxant effect of N-acetylprocainamide on methacholine-induced contraction, whereas apamin (100 nM), 4-aminopyridine (300 microM), and glibenclamide (10 microM) did not affect it. These results suggest that N-acetylprocainamide, similar to procainamide, elicits tracheal smooth muscle relaxation mainly through the activation of plasma membrane K+ channels.
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Affiliation(s)
- T Nakahara
- Department of Molecular Pharmacology, Kitasato University School of Pharmaceutical Sciences, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan.
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Shigenobu K, Ikeda M, Maki N, Tanabe H. [Difference between first appraisal and clinical estimation appraisal in a new social insurance system covering long-term care service--in terms of dementia and non dementia]. Seishin Shinkeigaku Zasshi 2001; 102:717-21. [PMID: 11141836] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Affiliation(s)
- K Shigenobu
- Department of Neuropsychiatry, Ehime University School of Medicine
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36
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Tanaka H, Shigenobu K. [Isolated atrial tissue preparation for evaluation of cardioactive agents]. Nihon Yakurigaku Zasshi 2001; 117:203-10. [PMID: 11288490 DOI: 10.1254/fpj.117.203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Isolated atrial tissue preparations provide convenient models for studying drug effects on the myocardium. However, there are several points we must be aware of. Interventions which change the beating rate also affect contractile force (Starling's Law). The membrane currents involved in the action potential as well as the excitation-contraction mechanisms differ between the atria and ventricle. Some membrane currents present only in the sino-atrial node and atrial myocardium may provide targets for novel bradycardiac agents and anti-atrial fibrillatory agents, respectively. The atrial tissue contains non-myocardial cells such as autonomic neurons and endocardial endothelial cells, which may be involved in the responses to various pharmacological stimuli.
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Affiliation(s)
- H Tanaka
- Department of Pharmacology, Toho University School of Pharmaceutical Sciences, Miyama 2-2-1, Funabashi, Chiba 274-8510, Japan.
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Tanaka Y, Mitani A, Igarashi T, Someya S, Otsuka K, Imai T, Yamaki F, Tanaka H, Saitoh M, Nakazawa T, Noguchi K, Hashimoto K, Shigenobu K. HNS-32, a novel azulene-1-carboxamidine derivative, inhibits nifedipine-sensitive and -insensitive contraction of the isolated rabbit aorta. Naunyn Schmiedebergs Arch Pharmacol 2001; 363:344-52. [PMID: 11284450 DOI: 10.1007/s002100000368] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The vasorelaxant profile of a novel azulene-1-carboxamidine derivative, HNS-32 [N1,N1-dimethyl-N2-(2-pyridylmethyl)-5-isopropyl-3,8-dimethyl-azulene-1-carboxamidine, CAS 186086-10-2], was investigated in the isolated rabbit aorta precontracted with high KCl, noradrenaline (NA) or phorbol 12, 13-dibutyrate (PDBu) and compared with those of nifedipine and nitroglycerin. In preparations without endothelium, HNS-32 elicited concentration-dependent, full inhibition of contractions elicited by high KCI (80 mM), NA (3x10(-6) M) or PDBu (10(-6) M). In contrast, nifedipine inhibited only the contraction elicited by membrane depolarization with high KCl. Nitroglycerin also attenuated high-KCl-, NA- and PDBu-elicited contractions effectively, although full suppression was obtained only for NA-elicited contraction. Whilst the relaxant effect of HNS-32 was not affected by the presence of endothelium, the relaxant response to acetylcholine was endothelium dependent. Addition of excess Ca2+ restored both the HNS-32-reduced tension in muscle precontracted with high KCI and the nifedipine-mediated tension decrease. Relaxation elicited by HNS-32 was not affected by the adenylate cyclase inhibitor, 9-(tetrahydro-2'-furyl)adenine (SQ 22,536, 10(-4) M), the soluble guanylate cyclase inhibitor, 1H-(1,2,4)-oxadiazolo-(4,3-a)-quinoxalin-1-one (ODQ, 10(-5) M) or a cocktail of K+ channel blockers (glybenclamide 10(-6) M, tetraethylammonium 2x10(-3) M, apamin 10(-7) M, 4-aminopyridine 10(-4) M and Ba2+ 10(-5) M). These findings indicate that HNS-32 inhibits both L-type Ca2+ channel-dependent and -independent vascular contraction. Blockade of Ca2+ entry through L-type Ca2+ channels may be involved in the inhibitory effect of HNS-32 on the contraction due to membrane depolarization with high KCl. On the other hand, HNS-32 seems to inhibit Ca2+ channel-independent contraction via mechanism(s) other than elevation of cyclic nucleotides (cAMP and cGMP) and opening of K+ channels.
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Affiliation(s)
- Y Tanaka
- Department of Pharmacology, Toho University School of Pharmaceutical Sciences, Funabashi-City, Chiba, Japan.
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Nebu A, Ikeda M, Fukuhara R, Komori K, Maki N, Hokoishi K, Shigenobu K, Kikuchi T, Tanabe H. Utility of (99m)Tc-HM-PAO SPECT hippocampal image to diagnose early stages of Alzheimer's disease using semiquantitative analysis. Dement Geriatr Cogn Disord 2001; 12:153-7. [PMID: 11173889 DOI: 10.1159/000051250] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVE Examination of the utility of (99m)Tc-hexamethylpropylene amine oxide ((99m)Tc-HM-PAO) SPECT hippocampal image to diagnose early stages of Alzheimer's disease (AD) using semiquantitative analysis. SUBJECTS 10 early-stage AD patients and 8 normal sex-matched elderly controls. SETTING Outpatient division of the Ehime University Hospital. METHOD We performed (99m)Tc-HM-PAO SPECT perfusion imaging in each subject. A semiquantitative method of assessing regional variation was used. The regions of interest for temporal regions were set at images parallel to the long axis of the hippocampal formation which were reconstructed at 30 degrees negative to the orbitomeatal line and those for other regions were set on ordinary transaxial images. RESULTS The regional cerebral blood flow ratio of the bilateral medial temporal lobe at the hippocampal image was significantly lower in the AD subjects than in the normally aged controls without any other differences in ordinary transaxial images. CONCLUSION This study suggests that (99m)Tc-HM-PAO SPECT hippocampal images might be a helpful tool for the diagnosis of very-early-stage AD.
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Affiliation(s)
- A Nebu
- Department of Neuropsychiatry, Ehime University School of Medicine, Ehime, Japan
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Noguchi K, Ito C, Isobe Y, Fukushima K, Tanaka Y, Tanaka H, Shigenobu K. Effects of 5-HT(4) receptor agonist prokinetic agents on the action potential parameters of isolated rabbit myocardium. Pharmacology 2001; 62:73-9. [PMID: 11174075 DOI: 10.1159/000056074] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The effects of TS-951, a novel gastrointestinal prokinetic agent with 5-HT(4) receptor agonistic action, on the action potential parameters of isolated rabbit Purkinje fiber, ventricular muscle and sinoatrial node, and on the spontaneously beating rates of isolated rabbit right atria were compared with those of cisapride. TS-951 had no effect on the action potential parameters in both rabbit Purkinje fiber and ventricular muscle preparations. However, cisapride significantly prolonged action potential duration (APD) in both preparations. Both TS-951 and cisapride produced a negative chronotropic effect in rabbit right atria; TS-951 and cisapride at 3 x 10(-5) mol/l reduced the beating rate by about 20 and 40%, respectively. In the sinoatrial node preparations, TS-951 (3 x 10(-5) mol/l) as well as cisapride (10(-6) mol/l) prolonged cycle length and APD and reduced the diastolic depolarization rate. These results indicate that TS-951 does not appear to possess electrophysiological features leading to cardiotoxicity such as QT prolongation and, thus, torsades de pointes in common with cisapride.
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Affiliation(s)
- K Noguchi
- Pharmacology Laboratory, Pharmaceutical Research Laboratories, Taisho Pharmaceutical Co., Ohmiya, Saitama, Japan.
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Nishimaru K, Makuta R, Tanaka Y, Tanaka H, Shigenobu K. Pharmacological properties of excitation-contraction mechanisms in isolated mouse left atria. Pharmacology 2001; 62:87-91. [PMID: 11174077 DOI: 10.1159/000056076] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Effects of 4-aminopyridine (4-AP), nicardipine and ryanodine on the action potential and contractile force were examined in isolated mouse left atria. The mouse left atria had an action potential with an extremely short duration and two phases of repolarization; action potential duration at 50% repolarization was 6.7 +/- 0.4 ms (n = 15). The action potential duration, as well as contractile force, was increased by 4-AP (at 100 micromol/l and 1 mmol/l). Nicardipine (3 micromol/l), which is known to greatly reduce the contractile force in atria of most other experimental animal species, had no significant effect on the action potential and decreased contractile force by only 40% in mouse atria. Ryanodine (10 nmol/l) decreased the contractile force by 90% of basal value. At 100 nmol/l, ryanodine slightly affected the action potential configuration, which could be explained by indirect effects through inhibition of Ca(2+) release from the sarcoplasmic reticulum. The extremely short action potential duration and the highly sarcoplasmic reticulum-dependent contraction of the mouse atria appear to underlie its unique response to agonists.
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Affiliation(s)
- K Nishimaru
- Department of Pharmacology, Toho University School of Pharmaceutical Sciences, Funabashi, Chiba, Japan
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Nishimaru K, Kobayashi M, Matsuda T, Tanaka Y, Tanaka H, Shigenobu K. alpha-Adrenoceptor stimulation-mediated negative inotropism and enhanced Na(+)/Ca(2+) exchange in mouse ventricle. Am J Physiol Heart Circ Physiol 2001; 280:H132-41. [PMID: 11123227 DOI: 10.1152/ajpheart.2001.280.1.h132] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Mechanisms underlying the negative inotropic response to alpha-adrenoceptor stimulation in adult mouse ventricular myocardium were studied. In isolated ventricular tissue, phenylephrine (PE), in the presence of propranolol, decreased contractile force by approximately 40% of basal value. The negative inotropic response was similarly observed under low extracellular Ca(2+) concentration ([Ca(2+)](o)) conditions but was significantly smaller under high-[Ca(2+)](o) conditions and was not observed under low-[Na(+)](o) conditions. The negative inotropic response was not affected by nicardipine, ryanodine, ouabain, or dimethylamiloride (DMA), inhibitors of L-type Ca(2+) channel, Ca(2+) release channel, Na(+)-K(+) pump, or Na(+)/H(+) exchanger, respectively. KB-R7943, an inhibitor of Na(+)/Ca(2+) exchanger, suppressed the negative inotropic response mediated by PE. PE reduced the magnitude of postrest contractions. PE caused a decrease in duration of the late plateau phase of action potential and a slight increase in resting membrane potential; time courses of these effects were similar to that of the negative inotropic effect. In whole cell voltage-clamped myocytes, PE increased the L-type Ca(2+) and Na(+)/Ca(2+) exchanger currents but had no effect on the inwardly rectifying K(+), transient outward K(+), or Na(+)-K(+)-pump currents. These results suggest that the sustained negative inotropic response to alpha-adrenoceptor stimulation of adult mouse ventricular myocardium is mediated by enhancement of Ca(2+) efflux through the Na(+)/Ca(2+) exchanger.
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Affiliation(s)
- K Nishimaru
- Department of Pharmacology, Toho University School of Pharmaceutical Sciences, Chiba 274-8510, Japan
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Abstract
Efonidipine is a dihydropyridine Ca2+ antagonist with inhibitory effects on both L-type and T-type Ca2+ channels and potent bradycardiac activity especially in patients with high heart rate. In the present study, we examined the frequency dependence of efonidipine action on the T-type Ca2+ channel in isolated guinea-pig ventricular myocytes. The potency of efonidipine to inhibit the T-type Ca2+ current was higher under higher stimulation frequencies. The IC50 values were 1.3 x 10(-8), 2.0 x 10(-6) and 6.3 x 10(-6) M under stimulation frequencies of 1, 0.2 and 0.05 Hz, respectively. The reduction of T-type Ca2+ current amplitude was not accompanied by change in the time course of current decay. Efonidipine (10 microM) inhibited T-type Ca2+ current elicited by depolarization from holding potentials ranging from -90 to -30 mV by about 30%; the voltage-dependence of steady-state inactivation was not changed by the drug. Efonidipine slowed the recovery from inactivation following an inactivating prepulse. In conclusion, efonidipine was shown to have frequency-dependent inhibitory effects on the T-type Ca2+ channel, which could be explained by slow dissociation of the drug from the inactivated state of the channel.
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Affiliation(s)
- H Masumiya
- Department of Pharmacology, Toho University School of Pharmaceutical Sciences, Funabashi, Chiba, Japan
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Abstract
PURPOSE To determine whether the Short-Memory Questionnaire (SMQ) being administered by caregivers to patients with Alzheimer's disease (AD) is also valid when given to patients with vascular dementia (VaD). METHODS Subjects were 58 patients with VaD, 26 patients with cerebrovascular disorders free of cognitive deficit (CVD) and 62 healthy controls. All subjects received the Mini-Mental State Examination (MMSE), and their primary caregivers (or family members with same household) received the SMQ. RESULTS In the VaD patients, the SMQ score was highly correlated with the MMSE score. When 39/40 was defined as a cutoff point based on the results of previous study, the SMQ properly classified 55 of the 58 VaD patients and 61 of the 62 controls, but only about half of the 26 CVD patients, as cases. CONCLUSION The SMQ, a simple quantitative rating test for memory disturbance, is useful for the assessment and screening of VaD patients as well as AD patients, although careful attention should be paid to the assessment of CVD patients.
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Affiliation(s)
- N Maki
- Department of Neuropsychiatry, Ehime University School of Medicine, Shigenobu-chou Onsen-gun, Ehime 791-0295, Japan.
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Shigenobu K, Ikeda M, Maki N, Tanabe H, Matsuura C. [Difference between first appraisal and clinical estimation appraisal in a new social insurance system covering long-term care service--in terms of outpatients and inpatients]. Nihon Ronen Igakkai Zasshi 2000; 37:1009-11. [PMID: 11201177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
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Tanaka Y, Someya S, Tanaka H, Tsuru H, Shigenobu K. Potentiation of stretch-induced tone in the rabbit facial vein by an isoquinoline derivative, LOE 908. Naunyn Schmiedebergs Arch Pharmacol 2000; 362:577-80. [PMID: 11138851 DOI: 10.1007/s002100000330] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The rabbit facial vein exhibits extracellular Ca2+- and temperature-dependent spontaneous myogenic tone in response to stretch. The present study aimed to elucidate pharmacological characteristics of Ca2+ entry mechanisms responsible for the stretch-induced tension development of the rabbit facial vein. Ca2+- and temperature-sensitive vascular tone in response to stretch was refractory to L-type Ca2+ channel blockers such as nifedipine and diltiazem but was abolished by papaverine or SK&F 96365 which blocks both receptor- and store-operated Ca2+ channels. Interestingly, LOE 908, another type of voltage-independent Ca2+-permeable channel blocker, showed augmentation of the stretch-induced vascular tone instead of inhibition. Potentiation by LOE 908 of stretch-induced vascular tone was also extracellular Ca2+-dependent and counteracted by SK&F 96365. Membrane stretch-activated Ca2+ channels in the rabbit facial vein smooth muscle cells may have a unique characteristic that their opening is stimulated by LOE 908 and thus is distinguishable from other voltage-independent Ca2+-permeable channels.
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Affiliation(s)
- Y Tanaka
- Department of Pharmacology, Toho University School of Pharmaceutical Sciences, Chiba, Japan
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Naito A, Hasegawa H, Kurasawa T, Ohtake Y, Matsukawa H, Ezure Y, Tsuriya Y, Koike K, Shigenobu K. The therapeutic efficacy of VP-343, a selective vasopressin V2 receptor antagonist, in the experimental SIADH rat model. Biol Pharm Bull 2000; 23:1323-7. [PMID: 11085360 DOI: 10.1248/bpb.23.1323] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The aim of this work is to investigate the therapeutic efficacy of VP-343 ((N-[4-[[(2S,3aR)-2-hydroxy-2,3,3a,4-tetrahydropyrrolo[1,2-a]qunoxalin-5(1H)-yl]phenyl]-4'-methyl[1,1'-biphenyl]-2-carboxamide), a selective vasopressin V2 receptor antagonist, using the experimental SIADH (syndrome of inappropriate secretion of antidiuretic hormone) rat model. In the model, which was accomplished by administering continuously 1-desamino-8-D-arginine vasopressin (DDAVP), serum sodium levels (S(Na)) and serum osmolarity levels (S(Osm)) significantly and remarkably decreased, which was accompanied with hyper-osmolarity of urine and oliguria. VP-343 increased rapidly and dose-dependently S(Na) and S(Osm). VP-343 exhibited marked diuretic action and decreased urine osmolarity dose-dependently. In the SIADH rat model, all serum levels of chloride, calcium, creatinine, total cholesterol, and uric acid decreased when compared with normal levels. VP-343 increased all serum levels of chloride, calcium, and total cholesterol. These results indicate that VP-343 has efficacy to normalize the abnormalities in DDAVP-induced SIADH.
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Affiliation(s)
- A Naito
- Sagami Research Laboratory, Wakamoto Pharmaceutical Co., Ltd., 378 Kanade, Ohi-machi, Ashigarakamigun, Kanagawa, Japan.
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Tanaka Y, Hayakawa S, Imai T, Akutsu A, Hirano H, Tanaka H, Nakahara T, Ishii K, Shigenobu K. Possible involvement of endothelium-derived hyperpolarizing factor (EDHF) in the depressor responses to platelet activating factor (PAF) in rats. Br J Pharmacol 2000; 131:1113-20. [PMID: 11082118 PMCID: PMC1572437 DOI: 10.1038/sj.bjp.0703681] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
1. In anaesthetized rats, platelet activating factor (PAF; 1 microg kg(-1)) decreased mean arterial blood pressure by around 60 mmHg (n=18). This depressor response was completely blocked by the PAF antagonist, CV-6209 (1 mg kg(-1)), indicating the role of PAF-specific receptor in the response. 2. N(G)-nitro-L-arginine methyl ester (L-NAME; 50 mg kg(-1)), an NO synthase inhibitor, profoundly elevated systemic blood pressure (n=19), indicating an important role of NO in the basal blood pressure regulation. The depressor response to PAF (1 microg kg(-1)) normalized against that to sodium nitroprusside (SNP) (10 microg kg(-1)) was not substantially different between rats treated without and with L-NAME (n=4). In contrast, the depressor effect of acetylcholine (0.03 - 1.0 microg kg(-1)) normalized against that of SNP (10 microg kg(-1)) was significantly attenuated by L-NAME (n=5). 3. Charybdotoxin (0.4 mg kg(-1)) plus apamin (0.2 mg kg(-1)) significantly attenuated the depressor response to PAF (1 microg kg(-1)) (n=5) without affecting the blood pressure change due to SNP (1 mg kg(-1)) (n=3). Charybdotoxin (0.4 mg kg(-1)) (n=4) or apamin (0.2 mg kg(-1)) (n=4) alone did not affect the PAF-induced depressor response. 4. These findings suggest that EDHF may make a significant contribution to the depressor response to PAF in rats. Although NO plays the determinant role in the basal blood pressure regulation, its contribution to PAF-produced depressor response seems to be less as compared with that to the depressor response to acetylcholine.
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Affiliation(s)
- Y Tanaka
- Department of Pharmacology, Toho University School of Pharmaceutical Sciences, 2-2-1 Miyama, Funabashi-City, Chiba 274-8510, Japan
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Tanaka Y, Kamibayashi M, Yamaki F, Saitoh M, Nakazawa T, tanaka H, Noguchi K, Hashimoto K, Shigenobu K. Relaxant Action of Azulene-1-carboxamidine Derivative N1, N1-dimethyl- N2-(2-pyridylmethyl)-5-isopropyl -3,8-dimethylazulene-1-carboxamidine (HNS-32) in Pig Coronary Artery. ACTA ACUST UNITED AC 2000. [DOI: 10.1211/146080800128736268] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
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Nakahara T, Moriuchi H, Yunoki M, Kubota Y, Tanaka Y, Sakamato K, Shigenobu K, Ishii K. Involvement of K(+) channel in procainamide-induced relaxation of bovine tracheal smooth muscle. Eur J Pharmacol 2000; 402:143-9. [PMID: 10940368 DOI: 10.1016/s0014-2999(00)00467-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The relaxant effect of procainamide, a class Ia antiarrhythmic agent, was examined in bovine tracheal smooth muscle. Procainamide produced concentration-dependent decreases in tension and full relaxation in the preparations contracted with methacholine (0.3 microM). By comparison, in preparations contracted with 40 mM K(+), procainamide had only slight relaxant effects. The relaxant effects of cromakalim and salbutamol on 40 mM K(+)-contracted preparations were significantly (P<0.01) smaller than those on 0.3 microM methacholine-contracted ones. On the other hand, the concentration-response relationships for quinidine, lidocaine, mexiletine and propafenone were not so dramatically different between 0.3 microM methacholine- and 40 mM K(+)-contracted preparations. Tetraethylammonium (300 microM), iberiotoxin (30 nM) and Ba(2+) (1 mM) significantly (P<0.05) attenuated the relaxant effects of procainamide on methacholine-induced contractions, whereas apamin (100 nM), 4-aminopyridine (300 microM), and glibenclamide (10 microM) did not affect them. The inhibitory effect of a combination of iberiotoxin and Ba(2+) was greater than that of iberiotoxin or Ba(2+) alone (P<0.01). These results suggest that the activation of at least two types of K(+) (maxi-K(+) and inward rectifier K(+)) channels contributes to the procainamide-induced relaxation of bovine tracheal smooth muscle.
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Affiliation(s)
- T Nakahara
- Department of Molecular Pharmacology, Kitasato University School of Pharmaceutical Sciences, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan.
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Masumiya H, Tanaka Y, Tanaka H, Shigenobu K. Inhibition of T-type and L-type Ca(2+) currents by aranidipine, a novel dihydropyridine Ca(2+) antagonist. Pharmacology 2000; 61:57-61. [PMID: 10940777 DOI: 10.1159/000028381] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The effects of aranidipine, a novel dihydropyridine Ca(2+) channel antagonist, on membrane currents in guinea pig ventricular myocytes and on action potentials in rabbit sinoatrial node tissue were examined. In myocytes, aranidipine (10 nmol/l to 1 micromol/l) concentration-dependently decreased T-type and L-type Ca(2+) currents. Aranidipine (1 micromol/l) had little effect on K(+) currents. In the sinoatrial node, 0.1 micromol/l aranidipine increased cycle length, and decreased +V(max) and the slope of the phase 4 depolarization. Thus, inhibition of both T-type and L-type Ca(2+) currents by aranidipine may partly explain its potent negative chronotropic activity.
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Affiliation(s)
- H Masumiya
- Department of Pharmacology, Toho University School of Pharmaceutical Sciences, Funabashi, Chiba, Japan
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