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The effect of beta-stimulants on mua channels in the frog ventrieular cells

Research Project

Project/Area Number 01570065
Research Category

Grant-in-Aid for General Scientific Research (C)

Allocation TypeSingle-year Grants
Research Field Neurophysiology and muscle physiology
Research InstitutionHiroshima University

Principal Investigator

SEYAMA Issei  Department of Physiology., Professor, 医学部, 教授 (70034006)

Project Period (FY) 1989 – 1990
Project Status Completed (Fiscal Year 1991)
Budget Amount *help
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1990: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1989: ¥1,300,000 (Direct Cost: ¥1,300,000)
KeywordsNa channel / Phosphorylation / Metalolic regulation / A-kinase / beta-stimulant / heart muscle / βー刺識 / オイル隔絶膜電位固定法
Research Abstract

This experiment was designed to study the commitment of A-kinase system in the regulation of Na channel functions in the frog ventricular cells. The voltage clamp method using oilgap method was used to improve the spatical control of the membrane potential. 10 u M propranolol, beta-stimulant, does not change the transient membrane current through Na channel, I_<Na>, neither does so another stimulant, histamine. Forskoline, direct stimulant to adenylate cyclase, also fails to affect it. There are several reports that beta-stimulant suppressed I_<Na> via A-kinase system in the mammalian ventricular cells. One of the most serious problems in studying the change in INa for a long time is the shift of the voltage-dependency of inactivation process to the hyperpolarizing direction. This shift may spuriously produce a change in I_<Na> similar to those reported. Care was exercis in selecting the preparasions which do not produce the shift, comparing the inactivation curve before and after the … More stimulation of A-kinase system. Other concerning point is the expermental method. Because half of the cell membrane of a single cell is disrupted, critical malerials may be washied out from the intracellular phase, leading to an artificial loss of the control of channel. I have negated this possibility by confirming that beta-stimulant only enhances current through Ca channel, I_<Ca> in the experimental condition in which both I_<Na> and I_<Ca> are functioning. In spite of the conservative property in the amino acid sequence of the critical part of the Na channel, differdnce in the sensiivity of Na channel to mu-conotoxin between the skeletal and the nerve cells suggests a subtle change in molecular configuration. Thus, distinction of the response of Na channel to beta-stimulant may be due to differince in species. There remains possibility that this is due to an artifact, because the experimental condition in the mammalian preparatins is very strict and the extent of suppression of I_<Na> reported is very limited. All these experimental findings lead me to the conclusion that Na channels in the frog ventricular cells are not regulated by A-kinase systms. Less

Report

(3 results)
  • 1991 Final Research Report Summary
  • 1990 Annual Research Report
  • 1989 Annual Research Report
  • Research Products

    (9 results)

All Other

All Publications (9 results)

  • [Publications] K.Sumii,H.Miyoshi,K.Yamaoka,I.Seyama: "The effect of β-stimulants on Na channels in the frog ventricular cells"

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1991 Final Research Report Summary
  • [Publications] K.Tsuji,T.Kawanishi,S.Handa,H.Kamano,J.Iwasa,I.Seyama: "The effect of structural modification ofseveral groups on the D-ring of grayanotoxin on its depolarization potency in squid giant axons" J.Phamacol.exp.Therap.

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1991 Final Research Report Summary
  • [Publications] K. Sumii, H. Miyoshi, K. Yamaoka and I. Seyama: "The effect of bera-stimulants on Na channels in the frog ventricular cells."

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1991 Final Research Report Summary
  • [Publications] K. Tsuji, T. Kawanishi, S. Handa, H. Kamano, J. Iwasa and I. Seyama: "The effect of structural moification of several groups on the D-ring of grayanotoxin on its depolairzation potency in squid giant axon" J. Pharmacol exp. therap.

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1991 Final Research Report Summary
  • [Publications] I.Sayama,M.Miyoshi,K.Tsuji: "The effect of βーstimulants on Na channels in the frog ventricular cells."

    • Related Report
      1990 Annual Research Report
  • [Publications] K.Tsuji,T.Kawanishi,S.Handa,H.Kamano,J.Iwasa,I.Seyama: "The effect of structural modification of several groups on the Dーring of grayanotoxin on its depolarization potency in sguid giant axon" J.Phamacol.Exp.Therap.

    • Related Report
      1990 Annual Research Report
  • [Publications] H.Miyoshi,K.Yamaoka & I.Seyama: "Characteristics of sodium channel kinetics in the frog ventricular cell." Excerpta Medica Current Clinical Practice series. 56. 15-24 (1989)

    • Related Report
      1989 Annual Research Report
  • [Publications] H.Miyoshi,M.Yakehiro,A.Fujiwara & I.Seyama: "Characterization of the Inactivation Process of the Sodium Channel in Frog Ventricular Cells" Hiroshima J.Med.Sci. 37. 139-143 (1988)

    • Related Report
      1989 Annual Research Report
  • [Publications] H.Miyoshi & I.Seyama: "An Investigation on the Inactivation Process of Sodium Currents in Single Frog Ventricular Cells." Japanese Journal of Physiology. 39. 371-383 (1989)

    • Related Report
      1989 Annual Research Report

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Published: 1989-04-01   Modified: 2016-04-21  

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