The Experts below are selected from a list of 190836 Experts worldwide ranked by ideXlab platform

Katsunori Noritake - One of the best experts on this subject based on the ideXlab platform.

  • lightweight virtualized evolved packet core architecture for future mobile communication
    Wireless Communications and Networking Conference, 2015
    Co-Authors: Hiroki Baba, Minoru Matsumoto, Katsunori Noritake
    Abstract:

    The accommodation of machine-to-machine (M2M) terminals in mobile networks is important; therefore, future network architecture supporting M2M services is of intense interest to mobile network operators. We propose an implemental architecture of a virtualized evolved packet core (vEPC) to accommodate M2M services. The proposed architecture deploys dedicated vEPCs based on the functional requirements of services. Every vEPC is optimized by eliminating EPC components or replacing standardized interface protocols with Internal Application interworking. We confirm the validity of the proposed architecture by experimentally evaluating CPU resource consumption. We also confirm that the proposed architecture reduces CPU time consumption by up to 27% by reducing signaling message volume, and improved performance is observed independently with M2M terminal mobility or communication characteristics.

  • WCNC - Lightweight virtualized evolved packet core architecture for future mobile communication
    2015 IEEE Wireless Communications and Networking Conference (WCNC), 2015
    Co-Authors: Hiroki Baba, Matsumoto Minoru, Katsunori Noritake
    Abstract:

    The accommodation of machine-to-machine (M2M) terminals in mobile networks is important; therefore, future network architecture supporting M2M services is of intense interest to mobile network operators. We propose an implemental architecture of a virtualized evolved packet core (vEPC) to accommodate M2M services. The proposed architecture deploys dedicated vEPCs based on the functional requirements of services. Every vEPC is optimized by eliminating EPC components or replacing standardized interface protocols with Internal Application interworking. We confirm the validity of the proposed architecture by experimentally evaluating CPU resource consumption. We also confirm that the proposed architecture reduces CPU time consumption by up to 27% by reducing signaling message volume, and improved performance is observed independently with M2M terminal mobility or communication characteristics.

Hiroki Baba - One of the best experts on this subject based on the ideXlab platform.

  • lightweight virtualized evolved packet core architecture for future mobile communication
    Wireless Communications and Networking Conference, 2015
    Co-Authors: Hiroki Baba, Minoru Matsumoto, Katsunori Noritake
    Abstract:

    The accommodation of machine-to-machine (M2M) terminals in mobile networks is important; therefore, future network architecture supporting M2M services is of intense interest to mobile network operators. We propose an implemental architecture of a virtualized evolved packet core (vEPC) to accommodate M2M services. The proposed architecture deploys dedicated vEPCs based on the functional requirements of services. Every vEPC is optimized by eliminating EPC components or replacing standardized interface protocols with Internal Application interworking. We confirm the validity of the proposed architecture by experimentally evaluating CPU resource consumption. We also confirm that the proposed architecture reduces CPU time consumption by up to 27% by reducing signaling message volume, and improved performance is observed independently with M2M terminal mobility or communication characteristics.

  • WCNC - Lightweight virtualized evolved packet core architecture for future mobile communication
    2015 IEEE Wireless Communications and Networking Conference (WCNC), 2015
    Co-Authors: Hiroki Baba, Matsumoto Minoru, Katsunori Noritake
    Abstract:

    The accommodation of machine-to-machine (M2M) terminals in mobile networks is important; therefore, future network architecture supporting M2M services is of intense interest to mobile network operators. We propose an implemental architecture of a virtualized evolved packet core (vEPC) to accommodate M2M services. The proposed architecture deploys dedicated vEPCs based on the functional requirements of services. Every vEPC is optimized by eliminating EPC components or replacing standardized interface protocols with Internal Application interworking. We confirm the validity of the proposed architecture by experimentally evaluating CPU resource consumption. We also confirm that the proposed architecture reduces CPU time consumption by up to 27% by reducing signaling message volume, and improved performance is observed independently with M2M terminal mobility or communication characteristics.

Katsuhiko Muraki - One of the best experts on this subject based on the ideXlab platform.

  • cromakalim induced membrane current in guinea pig tracheal smooth muscle cells
    European Journal of Pharmacology, 2000
    Co-Authors: Yuichiro Matsushita, Katsuhiko Muraki, Yuji Imaizumi, Satoshi Henmi, Minoru Watanabe
    Abstract:

    The characteristics of the cromakalim-induced membrane current were examined in single tracheal myocytes of the guinea-pig under voltage-clamp conditions. When K(+) concentrations in the pipette and bathing solutions were approximately 140 mM, cromakalim activated a membrane current (I(crom)) which was inward at -60 mV and reversed at -2 mV. I(crom) was blocked by 10 microM glibenclamide and potentiated when the ATP concentration in the pipette solution was decreased. The K(d) and Hill coefficient of glibenclamide for I(crom) block were 200 nM and 1.05, respectively. Application of the tyrosine kinase inhibitors, genistein and alpha-cyano-3-ethoxy-4-hydroxy-5-phenylthiomethylcinnamamid (ST638), reduced I(crom) in a concentration-dependent manner. Daidzein, which does not inhibit tyrosine kinase, was about 10 times less effective than genistein. Herbimycin A had no effect on I(crom). Internal Application of these inhibitors from the pipette did not affect I(crom). In conclusion, cromakalim is a potent activator of the ATP-sensitive K(+) channel (K(ATP) channel) in guinea-pig tracheal myocytes. The inhibition of I(crom) by genistein and ST638 may be due to the direct block of the channel from outside.

  • Effects of noradrenaline on membrane currents and action potential shape in smooth muscle cells from guinea-pig ureter.
    The Journal of Physiology, 1994
    Co-Authors: Katsuhiko Muraki, Yuji Imaizumi, M. Watanabe
    Abstract:

    1. The effects of noradrenaline (NA) on action potential shape and underlying membrane currents were examined in single smooth muscle cells freshly isolated from the ureter of the guinea-pig. 2. The voltage-dependent Ca2+ current (ICa) elicited upon depolarization from -50 to 0 mV was reduced by 27% upon Application of 10 microM NA. This reduction was inhibited or converted to potentiation by Internal Application of low molecular weight heparin or 5 mM EGTA, indicating that it may be mediated by Ca(2+)-dependent Ca2+ channel inactivation via inositol 1,4,5-trisphosphate production and subsequent Ca2+ release from intracellular Ca2+ storage sites. 3. In contrast, Ba2+ current (IBa) through Ca2+ channels was potentiated by 36% in the presence of 10 microM NA. Internal Application of GTP gamma S made it difficult to remove potentiation of IBa by wash-out; Internal Application of GDP beta S abolished potentiation. 4. NA caused a greater reduction in the transient Ca(2+)-dependent K+ current (IK(Ca)) upon depolarization than it did in ICa. This reduction was inhibited by Internally applied heparin, suggesting that the amount of releasable Ca2+ in the storage sites was markedly reduced in the presence of NA. The sustained component of IK(Ca) which gradually increased during depolarization was also reduced by NA. 5. Action potential duration, which was recorded in a standard solution containing Ca2+, was prolonged by the Application of NA. 6. It can be concluded that Ca2+ channel activity in ureter smooth muscle cells is regulated by a dual mechanism: Ca(2+)-dependent inhibition and GTP-binding protein-mediated potentiation. Under physiological conditions, both ICa and IK(Ca) were reduced by NA but the reduction of IK(Ca) was much larger than that of ICa; this results in an increase in net inward current during the action potential plateau and prolongs the action potential.

R. J. French - One of the best experts on this subject based on the ideXlab platform.

  • Sodium current inhibition by Internal calcium: A combination of open-channel block and surface charge screening?
    The Journal of Membrane Biology, 1995
    Co-Authors: Gerald W Zamponi, R. J. French
    Abstract:

    Internal Application of millimolar concentrations of calcium to batrachotoxin (BTX)-activated rat skeletal muscle sodium channels, bathed symmetrically in 200 m m NaCl, causes a reduction in apparent singlechannel amplitude without visibly increasing noise at a bandwidth of 50 Hz. A greater calcium-induced reduction occurred upon removal of external sodium ions. Internal calcium acted similarly in high ionic strength solutions (3 m NaCl), where surface charges are effectively screened, suggesting that calcium acts, in part, by binding within the pore and occluding the conducting pathway. In low ionic strength solutions (20 m m NaCl), Internal addition of N-Methyl-Glucamine (NMG) ions decreased the single channel amplitude consistent with screening of negative surface charges. An accurate description of the dose dependence of calcium inhibition, using either a simple blocking model, or rate theory calculations of ion permeation and block, also required surface charge screening. Hence, our data support the view that sodium current inhibition by Internal calcium arises from a combination of both open-channel block and surface charge effects.

Yuji Imaizumi - One of the best experts on this subject based on the ideXlab platform.

  • cromakalim induced membrane current in guinea pig tracheal smooth muscle cells
    European Journal of Pharmacology, 2000
    Co-Authors: Yuichiro Matsushita, Katsuhiko Muraki, Yuji Imaizumi, Satoshi Henmi, Minoru Watanabe
    Abstract:

    The characteristics of the cromakalim-induced membrane current were examined in single tracheal myocytes of the guinea-pig under voltage-clamp conditions. When K(+) concentrations in the pipette and bathing solutions were approximately 140 mM, cromakalim activated a membrane current (I(crom)) which was inward at -60 mV and reversed at -2 mV. I(crom) was blocked by 10 microM glibenclamide and potentiated when the ATP concentration in the pipette solution was decreased. The K(d) and Hill coefficient of glibenclamide for I(crom) block were 200 nM and 1.05, respectively. Application of the tyrosine kinase inhibitors, genistein and alpha-cyano-3-ethoxy-4-hydroxy-5-phenylthiomethylcinnamamid (ST638), reduced I(crom) in a concentration-dependent manner. Daidzein, which does not inhibit tyrosine kinase, was about 10 times less effective than genistein. Herbimycin A had no effect on I(crom). Internal Application of these inhibitors from the pipette did not affect I(crom). In conclusion, cromakalim is a potent activator of the ATP-sensitive K(+) channel (K(ATP) channel) in guinea-pig tracheal myocytes. The inhibition of I(crom) by genistein and ST638 may be due to the direct block of the channel from outside.

  • Effects of noradrenaline on membrane currents and action potential shape in smooth muscle cells from guinea-pig ureter.
    The Journal of Physiology, 1994
    Co-Authors: Katsuhiko Muraki, Yuji Imaizumi, M. Watanabe
    Abstract:

    1. The effects of noradrenaline (NA) on action potential shape and underlying membrane currents were examined in single smooth muscle cells freshly isolated from the ureter of the guinea-pig. 2. The voltage-dependent Ca2+ current (ICa) elicited upon depolarization from -50 to 0 mV was reduced by 27% upon Application of 10 microM NA. This reduction was inhibited or converted to potentiation by Internal Application of low molecular weight heparin or 5 mM EGTA, indicating that it may be mediated by Ca(2+)-dependent Ca2+ channel inactivation via inositol 1,4,5-trisphosphate production and subsequent Ca2+ release from intracellular Ca2+ storage sites. 3. In contrast, Ba2+ current (IBa) through Ca2+ channels was potentiated by 36% in the presence of 10 microM NA. Internal Application of GTP gamma S made it difficult to remove potentiation of IBa by wash-out; Internal Application of GDP beta S abolished potentiation. 4. NA caused a greater reduction in the transient Ca(2+)-dependent K+ current (IK(Ca)) upon depolarization than it did in ICa. This reduction was inhibited by Internally applied heparin, suggesting that the amount of releasable Ca2+ in the storage sites was markedly reduced in the presence of NA. The sustained component of IK(Ca) which gradually increased during depolarization was also reduced by NA. 5. Action potential duration, which was recorded in a standard solution containing Ca2+, was prolonged by the Application of NA. 6. It can be concluded that Ca2+ channel activity in ureter smooth muscle cells is regulated by a dual mechanism: Ca(2+)-dependent inhibition and GTP-binding protein-mediated potentiation. Under physiological conditions, both ICa and IK(Ca) were reduced by NA but the reduction of IK(Ca) was much larger than that of ICa; this results in an increase in net inward current during the action potential plateau and prolongs the action potential.