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Niwase T, Watanabe YX, Hirayama Y, Mukai M, Schury P, Andreyev AN, Hashimoto T, Iimura S, Ishiyama H, Ito Y, Jeong SC, Kaji D, Kimura S, Miyatake H, Morimoto K, Moon JY, Oyaizu M, Rosenbusch M, Taniguchi A, Wada M. Discovery of New Isotope ^{241}U and Systematic High-Precision Atomic Mass Measurements of Neutron-Rich Pa-Pu Nuclei Produced via Multinucleon Transfer Reactions. Phys Rev Lett 2023; 130:132502. [PMID: 37067317 DOI: 10.1103/physrevlett.130.132502] [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] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 01/26/2023] [Accepted: 02/16/2023] [Indexed: 06/19/2023]
Abstract
The new isotope ^{241}U was synthesized and systematic atomic mass measurements of nineteen neutron-rich Pa-Pu isotopes were performed in the multinucleon transfer reactions of the ^{238}U+^{198}Pt system at the KISS facility. The present experimental results demonstrate the crucial role of the multinucleon transfer reactions for accessing unexplored neutron-rich actinide isotopes toward the N=152 shell gap in this region of nuclides.
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Affiliation(s)
- T Niwase
- Wako Nuclear Science Center, Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization (KEK), Wako, Saitama 351-0198, Japan
| | - Y X Watanabe
- Wako Nuclear Science Center, Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization (KEK), Wako, Saitama 351-0198, Japan
| | - Y Hirayama
- Wako Nuclear Science Center, Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization (KEK), Wako, Saitama 351-0198, Japan
| | - M Mukai
- RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, Japan
| | - P Schury
- Wako Nuclear Science Center, Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization (KEK), Wako, Saitama 351-0198, Japan
| | - A N Andreyev
- School of Physics, Engineering and Technology, University of York, York YO10 5DD, United Kingdom
| | - T Hashimoto
- Institute for Basic Science, 70, Yuseong-daero 1689-gil, Yusung-gu, Daejeon 43000, Korea
| | - S Iimura
- Department of Physics, Rikkyo University, Tokyo 171-8501, Japan
| | - H Ishiyama
- RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, Japan
| | - Y Ito
- Advanced Science Research Center, Japan Atomic Energy Agency, Ibaraki 319-1195, Japan
| | - S C Jeong
- Wako Nuclear Science Center, Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization (KEK), Wako, Saitama 351-0198, Japan
| | - D Kaji
- RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, Japan
| | - S Kimura
- RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, Japan
| | - H Miyatake
- Wako Nuclear Science Center, Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization (KEK), Wako, Saitama 351-0198, Japan
| | - K Morimoto
- RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, Japan
| | - J-Y Moon
- Institute for Basic Science, 70, Yuseong-daero 1689-gil, Yusung-gu, Daejeon 43000, Korea
| | - M Oyaizu
- Wako Nuclear Science Center, Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization (KEK), Wako, Saitama 351-0198, Japan
| | - M Rosenbusch
- Wako Nuclear Science Center, Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization (KEK), Wako, Saitama 351-0198, Japan
| | - A Taniguchi
- Institute for Integrated Radiation and Nuclear Science, Kyoto University, Kumatori, Osaka 590-0494, Japan
| | - M Wada
- Wako Nuclear Science Center, Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization (KEK), Wako, Saitama 351-0198, Japan
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2
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Lee S, Hatano Y, Hara M, Masuzaki S, Tokitani M, Oyaizu M, Kurotaki H, Hamaguchi D, Nakamura H, Asakura N, Oya Y, Likonen J, Widdowson A, Jachmich S, Helariutta K, Rubel M. Tritium distribution analysis of Be limiter tiles from JET-ITER like wall campaigns using imaging plate technique and β-ray induced X-ray spectrometry. Fusion Engineering and Design 2020. [DOI: 10.1016/j.fusengdes.2020.111959] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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3
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Ashikawa N, Torikai Y, Asakura N, Otsuka T, Widdowson A, Rubel M, Oyaizu M, Hara M, Masuzaki S, Isobe K, Hatano Y, Heinola K, Baron-Wiechec A, Jachmich S, Hayashi T. Determination of retained tritium from ILW dust particles in JET. Nuclear Materials and Energy 2020. [DOI: 10.1016/j.nme.2019.100673] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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4
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Hirayama Y, Mukai M, Watanabe YX, Oyaizu M, Jeong SC, Kakiguchi Y, Schury P, Wada M, Miyatake H. Efficient two-color two-step laser ionization schemes of λ 1∼ 250 nm and λ 2 = 307.9 nm for heavy refractory elements-Measurements of ionization cross-sections and hyperfine spectra of tantalum and tungsten. Rev Sci Instrum 2019; 90:115104. [PMID: 31779376 DOI: 10.1063/1.5124444] [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] [Subscribe] [Scholar Register] [Received: 08/18/2019] [Accepted: 10/17/2019] [Indexed: 06/10/2023]
Abstract
We demonstrated efficient two-color two-step laser ionization schemes in the combined use of λ1 ∼ 250 nm and λ2 = 307.9 nm, which are applicable to heavy refractory elements with an atomic number in the wide range of Z = 69-78. We investigated newly observed ionization schemes of tantalum and tungsten atoms in an argon-gas-cell-based laser ion source for the efficient ionization of atoms of unstable nuclei through the two-color two-step laser resonance ionization technique. We experimentally determined the ionization cross sections from the measured saturation curves by solving the rate equations for the ground, intermediate, and ionization continuum populations. Hyperfine structures of these elements were also studied to deduce the isotope-shift, pressure-shift, and pressure-broadening in the resonance spectra of the excitation transitions in the argon gas cell. The electronic factor F255 of the excitation transition λ1 = 255.2115 nm between the ground and intermediate states was deduced from the measured isotope shifts of stable 182,183,184,186W isotopes. The ionization schemes investigated here are applicable to extract any isotopes of these elements by considering the measured pressure shift and nuclear isotope shift in optimizing the wavelength λ1.
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Affiliation(s)
- Y Hirayama
- Wako Nuclear Science Center (WNSC), Institute of Particle and Nuclear Studies (IPNS), High Energy Accelerator Research Organization (KEK), Saitama 351-0198, Japan
| | - M Mukai
- Graduate School of Pure and Applied Sciences, University of Tsukuba, Ibaraki 305-0006, Japan
| | - Y X Watanabe
- Wako Nuclear Science Center (WNSC), Institute of Particle and Nuclear Studies (IPNS), High Energy Accelerator Research Organization (KEK), Saitama 351-0198, Japan
| | - M Oyaizu
- Wako Nuclear Science Center (WNSC), Institute of Particle and Nuclear Studies (IPNS), High Energy Accelerator Research Organization (KEK), Saitama 351-0198, Japan
| | - S C Jeong
- Rare Isotope Science Project, Institute for Basic Science (IBS), Daejeon 305-811, South Korea
| | - Y Kakiguchi
- Wako Nuclear Science Center (WNSC), Institute of Particle and Nuclear Studies (IPNS), High Energy Accelerator Research Organization (KEK), Saitama 351-0198, Japan
| | - P Schury
- Wako Nuclear Science Center (WNSC), Institute of Particle and Nuclear Studies (IPNS), High Energy Accelerator Research Organization (KEK), Saitama 351-0198, Japan
| | - M Wada
- Wako Nuclear Science Center (WNSC), Institute of Particle and Nuclear Studies (IPNS), High Energy Accelerator Research Organization (KEK), Saitama 351-0198, Japan
| | - H Miyatake
- Wako Nuclear Science Center (WNSC), Institute of Particle and Nuclear Studies (IPNS), High Energy Accelerator Research Organization (KEK), Saitama 351-0198, Japan
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Gao-Takai M, Katayama-Ikegami A, Matsuda K, Shindo H, Uemae S, Oyaizu M. A low temperature promotes anthocyanin biosynthesis but does not accelerate endogenous abscisic acid accumulation in red-skinned grapes. Plant Sci 2019; 283:165-176. [PMID: 31128686 DOI: 10.1016/j.plantsci.2019.01.015] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2018] [Revised: 01/18/2019] [Accepted: 01/19/2019] [Indexed: 06/09/2023]
Abstract
The effect of temperature on the concentrations of anthocyanins and endogenous plant hormones [abscisic acid (ABA), auxin, and cytokinin] were investigated using the detached berries of two related red-skinned cultivars cv. 'Aki Queen' and 'Ruby Roman' of the table grape Vitis labrusca L. × Vitis vinifera L. The total anthocyanin concentration of both cultivars was lower when exposed to high rather than low temperatures after véraison (the onset of ripening). However, the responses to temperature differed between the two cultivars, and anthocyanin accumulation could occur in 'Ruby Roman' at a higher temperature than in 'Aki Queen'. High temperatures increased the expression of VlMybA1-2 and VlMybA1-3, which encode myeloblastosis (MYB)-related transcription factors; however, the expression of the anthocyanin biosynthesis-related structural genes uridine diphosphate-d-glucose: flavonoid 3-O-glucosyltransferase, flavonoid 3'5' hydroxylase, and flavonoid O-methyltransferase at different temperatures did not correspond with that of the expression of MybAs. The concentration of ABA and its derivatives increased under high temperatures, but that of auxin and cytokinin decreased. The observation that high temperatures induced the accumulation of ABA and expression of VlMybA1s but not the expression of anthocyanin biosynthesis-related structural genes implied the operation of a mechanism different from up-regulation of anthocyanin synthesis by VlMybA1s in the temperature response of grape berries.
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Affiliation(s)
- Mei Gao-Takai
- Faculty of Bioresources and Environmental Sciences, Ishikawa Prefectural University, 1-308 Suematsu, Nonoichi, Ishikawa 921-8836, Japan.
| | - Ayako Katayama-Ikegami
- Faculty of Bioresources and Environmental Sciences, Ishikawa Prefectural University, 1-308 Suematsu, Nonoichi, Ishikawa 921-8836, Japan
| | - Kenichi Matsuda
- Ishikawa Agriculture and Forestry Research Center, Agricultural Experiment Station, Sand Hill Place Agriculture Research Center, Kahoku 929-1126, Japan
| | - Hibiki Shindo
- Faculty of Bioresources and Environmental Sciences, Ishikawa Prefectural University, 1-308 Suematsu, Nonoichi, Ishikawa 921-8836, Japan
| | - Shintaro Uemae
- Faculty of Bioresources and Environmental Sciences, Ishikawa Prefectural University, 1-308 Suematsu, Nonoichi, Ishikawa 921-8836, Japan
| | - Miku Oyaizu
- Faculty of Bioresources and Environmental Sciences, Ishikawa Prefectural University, 1-308 Suematsu, Nonoichi, Ishikawa 921-8836, Japan
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6
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Hirayama Y, Miyatake H, Watanabe Y, Imai N, Ishiyama H, Jeong S, Jung H, Oyaizu M, Mukai M, Kimura S, Sonoda T, Wada M, Kim Y, Huyse M, Kudryavtsev Y, Van Duppen P. Beta-decay spectroscopy of r-process nuclei around N= 126. EPJ Web of Conferences 2016. [DOI: 10.1051/epjconf/201610908001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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7
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Sugai I, Oyaizu M, Takeda Y, Kawakami H, Kawasaki K, Hattori T, Kadono T. Sputtering angle effects by Kr mixing in N+ ion beam on the lifetime of nitrided carbon stripper foils. J Radioanal Nucl Chem 2014. [DOI: 10.1007/s10967-013-2665-x] [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: 10/26/2022]
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8
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Mukai M, Hirayama Y, Jeong SC, Imai N, Ishiyama H, Miyatake H, Oyaizu M, Watanabe YX, Kim YH. In-gas-cell laser ion source for KEK isotope separation system. Rev Sci Instrum 2014; 85:02B906. [PMID: 24593611 DOI: 10.1063/1.4827112] [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] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The KEK isotope separation system (KISS) is an element-selective isotope separator under development at RIKEN. The in-gas-cell laser ion source is a critical component of the KISS, a gas cell filled with argon gas of 50 kPa enclosed in a vacuum chamber. In the gas cell, nuclear reaction products are stopped (i.e., thermalized and neutralized) and transported by a laminar flow of argon to the ionization region just upstream of the gas outlet, and thereby an element of interest among those reaction products is selectively ionized by two-color resonant laser irradiation. Recently, we succeeded to extract laser-ionized Fe ions by injecting an energetic Fe beam into the gas cell. Recent off- and on-line test results were presented and discussed.
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Affiliation(s)
- M Mukai
- High Energy Accelerator Res Org. (KEK), Ibaraki 305-0801, Japan
| | - Y Hirayama
- High Energy Accelerator Res Org. (KEK), Ibaraki 305-0801, Japan
| | - S C Jeong
- High Energy Accelerator Res Org. (KEK), Ibaraki 305-0801, Japan
| | - N Imai
- High Energy Accelerator Res Org. (KEK), Ibaraki 305-0801, Japan
| | - H Ishiyama
- High Energy Accelerator Res Org. (KEK), Ibaraki 305-0801, Japan
| | - H Miyatake
- High Energy Accelerator Res Org. (KEK), Ibaraki 305-0801, Japan
| | - M Oyaizu
- High Energy Accelerator Res Org. (KEK), Ibaraki 305-0801, Japan
| | - Y X Watanabe
- High Energy Accelerator Res Org. (KEK), Ibaraki 305-0801, Japan
| | - Y H Kim
- High Energy Accelerator Res Org. (KEK), Ibaraki 305-0801, Japan
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9
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Hirayama Y, Jeong S, Watanabe Y, Imai N, Ishiyama H, Miyatake H, Oyaizu M, Kim Y, Mukai M, Sonoda T, Wada M, Huyse M, Kudryavtsev Y, Van Duppen P. Present Status of KEK Isotope Separation System. EPJ Web of Conferences 2014. [DOI: 10.1051/epjconf/20146611017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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10
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Jeong SC, Oyaizu M, Imai N, Hirayama Y, Ishiyama H, Miyatake H, Niki K, Okada M, Watanabe YX, Otokawa Y, Osa A, Ichikawa S. Wall-loss distribution of charge breeding ions in an electron cyclotron resonance ion source. Rev Sci Instrum 2012; 83:02A910. [PMID: 22380251 DOI: 10.1063/1.3670740] [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] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We investigated the ion-loss distribution on the sidewall of an electron cyclotron resonance (ECR) plasma chamber using the 18-GHz ECR charge breeder at the Tokai Radioactive Ion Accelerator Complex (TRIAC). Similarities and differences between the ion-loss distributions (longitudinal and azimuthal) of different ion species (i.e., radioactive (111)In(1+) and (140)Xe(1+) ions that are typical volatile and nonvolatile elements) was qualitatively discussed to understand the element dependence of the charge breeding efficiency. Especially, the similarities represent universal ion loss characteristics in an ECR charge breeder, which are different from the loss patterns of electrons on the ECRIS wall.
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Affiliation(s)
- S C Jeong
- Institute for Particle and Nuclear Physics (IPNS), High Energy Accelerator Research Organization (KEK), Oho 1-1, Tsukuba, Ibaraki 305-0801, Japan.
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11
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Jeong SC, Oyaizu M, Imai N, Hirayama Y, Ishiyama H, Miyatake H, Niki K, Okada M, Watanabe YX, Otokawa Y, Osa A, Ichikawa S. Wall-loss distribution of charge breeding ions in an electron cyclotron resonance ion source. Rev Sci Instrum 2011; 82:033508. [PMID: 21456738 DOI: 10.1063/1.3567802] [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] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The ion loss distribution in an electron cyclotron resonance ion source (ECRIS) was investigated to understand the element dependence of the charge breeding efficiency in an electron cyclotron resonance (ECR) charge breeder. The radioactive (111)In(1+) and (140)Xe(1+) ions (typical nonvolatile and volatile elements, respectively) were injected into the ECR charge breeder at the Tokai Radioactive Ion Accelerator Complex to breed their charge states. Their respective residual activities on the sidewall of the cylindrical plasma chamber of the source were measured after charge breeding as functions of the azimuthal angle and longitudinal position and two-dimensional distributions of ions lost during charge breeding in the ECRIS were obtained. These distributions had different azimuthal symmetries. The origins of these different azimuthal symmetries are qualitatively discussed by analyzing the differences and similarities in the observed wall-loss patterns. The implications for improving the charge breeding efficiencies of nonvolatile elements in ECR charge breeders are described. The similarities represent universal ion loss characteristics in an ECR charge breeder, which are different from the loss patterns of electrons on the ECRIS wall.
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Affiliation(s)
- S C Jeong
- High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801, Japan
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12
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Imai N, Jeong SC, Oyaizu M, Arai S, Fuchi Y, Hirayama Y, Ishiyama H, Miyatake H, Tanaka MH, Okada M, Watanabe YX, Ichikawa S, Kabumoto H, Osa A, Otokawa Y, Sato TK. KEKCB electron cyclotron resonance charge breeder at TRIAC. Rev Sci Instrum 2008; 79:02A906. [PMID: 18315161 DOI: 10.1063/1.2828070] [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] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The KEKCB is an electron cyclotron resonance (ECR) ion source for converting singly charged ions to multicharged ones at Tokai Radioactive Ion Accelerator Complex. By using the KEKCB, singly charged gaseous and nongaseous ions were converted to multicharged ones of A/q approximately 7 with efficiencies of 7% and 2%, respectively. The conversion efficiency was found to be independent of the lifetime of the radioactive nuclei having lifetimes of the order of one second. Three collimators located at the entrance and the exit of the KEKCB defined the beam axis and facilitated beam injection. Grinding and washing the surfaces of aluminum electrode and plasma chamber dramatically reduced impurities originating from the ECR plasma of the KEKCB.
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Affiliation(s)
- N Imai
- High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki, Japan.
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13
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Abstract
The effects of nefiracetam (DM-9384) on the neuronal nicotinic acetylcholine (ACh) receptor-channel were studied by the whole-cell patch clamp technique using PC12 cells. Nefiracetam had a dual effect on ACh-induced currents: it augmented the currents induced by low concentrations (10-30 microM) of ACh and suppressed those induced by high concentrations (100-1000 microM) of ACh. These effects were reversible after washing with drug-free solution. The stimulating effect of nefiracetam was clearly observed at a concentration of 10 microM, and slight increases in currents were detected even at 0.1 microM or 1 microM. Nefiracetam at 100 microM suppressed the currents induced by a low concentration (10 microM) of ACh. The rate of desensitization of ACh-induced current was greatly accelerated by nefiracetam, and this effect could not be reversed by washing with drug-free solution. When added to the internal pipette solution, the protein kinase A inhibitor KT 5720 (0. 6 microM), but not the protein kinase C inhibitor calphostin C (0.5 microM), abolished the nefiracetam stimulation of the ACh receptor. Pre-incubation of cells with 200 ng/ml pertussis toxin for 24 h also abolished the nefiracetam action. Thus, the nefiracetam modulation of the neuronal nicotinic ACh receptor-channel is exerted via G proteins and protein kinase A. The stimulation of the ACh receptor may be directly related to the cognitive enhancing action of nefiracetam.
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Affiliation(s)
- M Oyaizu
- Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Medical School, 303 E. Chicago Avenue, Chicago, IL 60611, USA
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Kurata Y, Hisatome I, Tsuboi M, Uenishi H, Zhang G, Oyaizu M, Sato R, Imanishi S. Effect of sulfhydryl oxidoreduction on permeability of cardiac tetrodotoxin-insensitive sodium channel. Life Sci 1998; 63:1023-35. [PMID: 9749825 DOI: 10.1016/s0024-3205(98)00364-6] [Citation(s) in RCA: 16] [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: 02/08/2023]
Abstract
Effects of sulfhydryl oxidizing and reducing agents on permeability of the tetrodotoxin (TTX)-insensitive Na-channel were investigated in guinea-pig ventricular myocytes using the whole-cell patch-clamp technique. Mercury chloride (HgCl2) at 1-100 microM irreversibly blocked Na+ currents with no significant changes in the gating kinetics. In contrast, the hydrophilic sulfhydryl oxidizing agent, thimerosal at 50-100 microM little affected Na+ permeation through the Na-channel. The Hg2+-induced block of Na+ current could be readily reversed by 1,4-dithiothreitol (DTT), an agent that reduces disulfide bonds. These results indicate that the formation of sulfur-Hg-sulfur bridge is essential for Hg2+ block. Pretreatment with DTT prevented the Hg2+ block of Na+ current, whereas Zn2+ and Cd2+ retained their abilities to block Na+ current after DTT treatment. An application of Zn2+ or Cd2+ resulted in the restoration of Hg2+ sensitivity of the DTT-treated channel. A conformational model for the Na-channel with multiple free sulfhydryl groups and native disulfide bonds could account for our experimental data regarding the effects of sulfhydryl modifying agents on the channel permeability. We conclude that the cardiac TTX-insensitive Na-channel contains functionally important free sulfhydryl groups and disulfide bonds which are accessible from the extracellular side by an aqueous pathway. These sulfhydryls would be capable of modulating the Na-channel permeability by affecting the conformation of channel pore region.
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Affiliation(s)
- Y Kurata
- Department of Physiology, Kanazawa Medical University, Ishikawa, Japan
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15
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Saito M, Sato R, Muñoz NM, Herrnreiter A, Oyaizu M, Kasugai H, Narahashi T, Leff AR. Association of granular exocytosis with Ca(2+)-activated K+ channels in human eosinophils. Am J Physiol 1997; 273:L16-21. [PMID: 9252535 DOI: 10.1152/ajplung.1997.273.1.l16] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We studied the mechanism of degranulation caused by Ca(2+)-activated K+ channels (KCa channels) in eosinophils isolated from mildly atopic donors using negative immunoselection. Stimulation of eosinophils with 0.1 microM platelet-activating factor (PAF) caused activation of single channels as recorded by the cell-attached patch-clamp technique. These channels were selectively permeable to K+ because the reversal potential was close to the equilibrium potential for K+. However, the channels were not permeable to Na+ or Cl- as demonstrated by ion substitution experiments. The calcium ionophore A-23187, at 1 microM, increased the K+ channel activity in the presence of Ca2+ in the external perfusate but did not induce channel activity in the absence of Ca2+. Similar results were obtained with another calcium ionophore, ionomycin (1 microM), and the Ca(2+)-releasing agent thapsigargin (10 microM). K+ channels activated by PAF and A-23187 had similar characteristics: two levels of single-channel conductances were observed, 10 +/- 1.5 and 22 +/- 1.7 pS as induced by PAF and 11 +/- 1.3 and 24 +/- 1.9 pS by A-23187; the mean open times of the large-conductance channels were 1.45 +/- 0.3 ms as induced by PAF and 1.26 +/- 0.5 ms by A-23187. These results indicate that PAF activates KCa channels. Both KCa currents and major basic protein release caused by A-23187 were blocked by quinidine. It is suggested that KCa channels are associated with granule secretion in human eosinophils.
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Affiliation(s)
- M Saito
- Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Medical School, Chicago 60611-3008, USA
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16
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Ishikawa K, Nakai S, Takenaka T, Kanamasa K, Hama J, Ogawa I, Yamamoto T, Oyaizu M, Kimura A, Yamamoto K, Yabushita H, Katori R. Short-acting nifedipine and diltiazem do not reduce the incidence of cardiac events in patients with healed myocardial infarction. Secondary Prevention Group. Circulation 1997; 95:2368-73. [PMID: 9170398 DOI: 10.1161/01.cir.95.10.2368] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [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: 02/04/2023]
Abstract
BACKGROUND The administration of calcium antagonists to patients with healed myocardial infarction is a controversial treatment. This study was conducted to elucidate the effect of short-acting nifedipine and diltiazem on cardiac events in patients with healed myocardial infarction. METHODS AND RESULTS A controlled clinical open trial of 1115 patients with healed myocardial infarction was carried out between 1986 and 1994. The patients included 595 who received no calcium antagonist, 341 who received short-acting nifedipine 30 mg/d, and 179 who received short-acting diltiazem 90 mg/d. The primary end points were cardiac events, which were defined as fatal or nonfatal recurrent myocardial infarction; death from congestive heart failure; sudden death; and hospitalization because of worsening angina, congestive heart failure, or premature ventricular contractions. Cardiac events occurred in 51 patients (8.6%) in the no-calcium-antagonist group and 54 (10.4%) in the calcium-antagonist group (odds ratio, 1.24; 95% CI, 0.83 to 1.85), demonstrating that the calcium antagonists did not reduce the incidence of cardiac events. Subgroup analysis revealed no beneficial effects of these drugs for reducing cardiac events in patients with such complications as hypertension or angina pectoris. CONCLUSIONS This study showed that use of short-acting nifedipine and diltiazem in this postmyocardial infarction population was associated with a 24% higher cardiac event rate, but this strong adverse trend did not reach statistical significance.
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Affiliation(s)
- K Ishikawa
- Kinki University, School of Medicine, Osaka, Japan
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17
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Ishikawa K, Kanamasa K, Hama J, Ogawa I, Takenaka T, Naito T, Yamamoto T, Nakai S, Oyaizu M, Kimura A, Yamamoto K, Katori R. Aspirin plus either dipyridamole or ticlopidine is effective in preventing recurrent myocardial infarction. Secondary Prevention Group. Jpn Circ J 1997; 61:38-45. [PMID: 9070958 DOI: 10.1253/jcj.61.38] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The efficacy of combining antiplatelet agents with low doses of aspirin to prevent cardiac events in patients with myocardial infarction was examined. A total of 1,083 patients with prior myocardial infarction were randomly divided into those who were (618) and were not (465) treated with antiplatelet agents, and observed for 12.5 +/- 18.5 months. Those treated with antiplatelet agents included 113 patients treated with aspirin (50 mg) plus dipyridamole (150 mg/day), 253 treated with aspirin (50 mg) plus ticlopidine (200 mg/day), and 252 treated with only 1 of the 3 antiplatelet agents. Cardiac events, including fatal or nonfatal recurrent myocardial infarction, death by congestive heart failure, and sudden death, occurred in 34 patients (7.3%) in the nontreatment group and in 19 patients (3.1%; p < 0.01) in the treatment group; odds ratio 0.40, 95% confidence interval 0.23-0.71. There were only 2 cardiac events (1.8%) in the aspirin + dipyridamole group (p < 0.05 vs nontreatment group: odds ratio 0.28: 0.08-1.03), and 5 such events (2.0%) in the aspirin + ticlopidine group (p < 0.01; odds ratio 0.28: 0.11-0.69). Subgroup analysis to exclude differences in the patients' background confirmed the efficacy of these antiplatelet agents. We conclude that combined treatment with low doses of aspirin plus either dipyridamole or ticlopidine is effective in preventing cardiac events in patients who have had prior myocardial infarction.
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Affiliation(s)
- K Ishikawa
- First Department of Internal Medicine, Kinki University, School of Medicine, Osaka, Japan
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18
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Ishikawa K, Kanamasa K, Ogawa I, Takenaka T, Naito T, Kamata N, Yamamoto T, Nakai S, Hama J, Oyaizu M, Kimura A, Yamamoto K, Aso N, Arai M, Yabushita H, Katori Y. Long-term nitrate treatment increases cardiac events in patients with healed myocardial infarction. Secondary Prevention Group. Jpn Circ J 1996; 60:779-88. [PMID: 8933241 DOI: 10.1253/jcj.60.779] [Citation(s) in RCA: 59] [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: 02/03/2023]
Abstract
BACKGROUND Nitrates dilate coronary arteries, ameliorate myocardial ischemia, minimize left ventricular remodeling, and reduce mortality in patients with acute myocardial infarction. However, the effects of long-term treatment with nitrates on cardiac events in patients with healed myocardial infarction are not known. METHODS AND RESULTS A total of 1,002 patients with healed myocardial infarction (789 male and 213 female) were randomly divided into 2 groups: treatment with nitrates or nontreatment. The mean observation period was 18.0 +/- 19.9 months. Primary end points were nonfatal and fatal recurrent myocardial infarction, death from congestive heart failure, and sudden death. Baseline characteristics of the 2 groups were also compared to determine any effects on outcome. Among the 621 cases treated with nitrates, 41 cases (6.6%) experienced cardiac events during the observation period, whereas only 12 of the 381 cases that were not treated with nitrates (3.1%) had cardiac events. This difference was statistically significant (p < 0.05; odds ratio 2.17; 95% confidence interval 1.13-4.19). There were no differences in the incidence of noncardiac death or being lost to follow-up between the 2 groups. Although the precise mechanism of this increase in the occurrence of cardiac events by long-term treatment with nitrates is not clear, nitrate tolerance with possible rebound and neurohormonal effects may be involved. CONCLUSION Long-term treatment with nitrates increased cardiac events in patients with healed myocardial infarction.
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Affiliation(s)
- K Ishikawa
- First Department of Medicine, Kinki University, School of Medicine, Osaka, Japan
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19
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Matzno S, Sato R, Takai H, Aida Y, Karasaki S, Oyaizu M, Nakamura N, Katori R. The effect of AL0671, a novel potassium channel opener, on potassium current in rat aortic smooth muscle cells. Gen Pharmacol 1995; 26:1327-34. [PMID: 7590127 DOI: 10.1016/0306-3623(94)00282-r] [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: 01/26/2023]
Abstract
1. We evaluated the mechanism of activation by AL0671, a novel potassium channel opener, of potassium current in rat aortic smooth muscle cells. 2. Under conditions of whole cell recording, AL0671 (1-1000 microM) markedly increased potassium current with a Hill coefficient of 2 and dissociation constant of 1.5 x 10(-4) M. This activation was completely inhibited by intracellular ATP. 3. Under inside-out patch conditions, the ATP-sensitive K+ channels (KATP) treated with AL0671 (100 microM) showed prolongation of the slower open time component and shortening of the slower closed time component without modification of channel conductance.
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Affiliation(s)
- S Matzno
- Basic Research Laboratories, Green Cross Corporation, Osaka, Japan
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Sato R, Koumi S, Hisatome I, Takai H, Aida Y, Oyaizu M, Karasaki S, Mashiba H, Katori R. A new class III antiarrhythmic drug, MS-551, blocks the inward rectifier potassium channel in isolated guinea pig ventricular myocytes. J Pharmacol Exp Ther 1995; 274:469-74. [PMID: 7616432] [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] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
We have studied the effects of MS-551 on the inward rectifier potassium channel (IK1) in isolated guinea-pig ventricular myocytes by use of whole-cell and single-channel recording techniques. MS-551 (5 microM) blocked the IK1 current. The percent blockade of the peak and steady-state IK1 current by MS-551 was constant at each test potential. In contrast 50 microM MS-551 failed to block either the sodium or the calcium current. Under cell-attached patch conditions, MS-551 reduced the open probability of IK1 channel activity by prolonging the interburst interval without changing either the unitary amplitude or the equilibrium potential. The blockade of IK1 was concentration-dependent. MS-551 did not change either the mean open time or mean closed time within a burst. Extracellular acidification (pH 6.4) strongly attenuated the effect of MS-551 on the open probability of IK1 channel activity when compared with its effect at pH 7.4. In summary, our results demonstrated that MS-551 blocked the IK1 channel. The neutral form of this drug molecules may penetrate the cardiac cell membrane via a hydrophobic pathway to block the steady-state IK1 current by reduction of open probability.
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Affiliation(s)
- R Sato
- First Department of Internal Medicine, Kinki University, Osaka, Japan
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Yoshida A, Hisatome I, Kotake H, Hirai S, Taniguchi S, Oyaizu M, Sato R, Kouchi T, Ueta Y, Mitani Y. Antiarrhythmic drugs inhibit the G-protein and K+ channels in the cultured thyroid cell line. J Pharmacol Exp Ther 1995; 273:702-8. [PMID: 7752073] [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] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
We examined the effects of antiarrhythmic drugs on the induction of cAMP by TSH (thyroid-stimulating hormone), using continuously cultured FRTL-5 rat thyroid cells. Group Ia antiarrhythmic drugs had no effect, but Group Ib antiarrhythmic drugs suppressed cAMP induction by TSH. These drugs suppressed cAMP induction in response to cholera toxin but did not inhibit TSH receptor binding or cAMP induction by forskolin. These results indicate that Group Ib antiarrhythmic drugs inhibit thyroid G-protein, resulting in a decrease in cAMP induction by TSH. We also examined the effect of antiarrhythmic drugs on K+ channels. Group Ia antiarrhythmic drugs had no effect on K+ channel activation by TSH and cAMP. On the other hand, Group Ib antiarrhythmic drugs suppressed K+ channel activation by TSH and cAMP. This indicates that the mechanism of suppression is not inhibition of TSH receptors or G-proteins but the direct suppression of K+ channels. Group Ib antiarrhythmic drugs inhibited thyroid Gs-protein and thyroid K+ channels. Considering the close relationship between G-protein and ion channels in the cardiac cell membrane, these different effects of Group Ia and Group Ib antiarrhythmic drugs on G-proteins and K+ channels are of interest. Further investigation is necessary to clarify the relationship between thyroid G-proteins and thyroid K+ channels.
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Affiliation(s)
- A Yoshida
- First Department of Internal Medicine, Tottori University School of Medicine, Yonago, Japan
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Ishikawa K, Kanamasa K, Hama J, Ogawa I, Takenaka T, Naito T, Kamata N, Nakai S, Yamamoto T, Oyaizu M. [Effects of drugs on preventing recurrent myocardial infarction in patients with healed myocardial infarction]. Jpn Circ J 1994; 58 Suppl 4:1288-1292. [PMID: 7699777 DOI: 10.1253/jcj.58.supplementiv_1288] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Affiliation(s)
- K Ishikawa
- First Department of Internal Medicine, Kinki University School of Medicine
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