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Regional differences in the pacemaker activity of the heart

Research Project

Project/Area Number 07044244
Research Category

Grant-in-Aid for international Scientific Research

Allocation TypeSingle-year Grants
SectionJoint Research
Research InstitutionRes.Inst.of Environ.Med., Nagoya Univ.

Principal Investigator

KODAMA Itsuo  Res.Inst.of Environ.Med., Nagoya Univ., Prof., 環境医学研究所, 教授 (30124720)

Co-Investigator(Kenkyū-buntansha) BOYATT Mark R  Dept.of Physiol., Univ.of Leeds, UK,Prof., 生理学, 教授
HONJO Haruo  Res.Inst.of Environ.Med., Nagoya Univ., Res.Assoc., 環境医学研究所, 助手 (70262912)
TOYAMA Junji  Res.Inst.of Environ.Med., Nagoya Univ., Prof., 環境医学研究所, 教授 (20023658)
Project Period (FY) 1995 – 1996
Project Status Completed (Fiscal Year 1996)
Budget Amount *help
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 1996: ¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1995: ¥1,800,000 (Direct Cost: ¥1,800,000)
Keywordssinoatrial node / spontaneous activity / action potential / ion channel / electrophysiology / heart / 自発活動電位 / イオン電流 / パッチクランプ / 4-aminopyridine / 細胞歩調取り機能 / 電気生理学的多様性 / 細胞内イオン動態
Research Abstract

The SA node is an inhomogeneous structure in terms of structure, properties and function. We have investigated the possible regional deferences in the role of various membrane currents in the pacemaker activity in rabbit SA node preparations. Block of L type Ca^<2+> current (I_<Ca>) by 2muM nifedipine abolished spontaneous action potentials in the center, but not in the periphery, in the intact SA node and small ball-like specimens of the SA node. In contrast, block of Na^+ current (I_<Na>) by 20muM TTX had no effect on the electrical activity in small balls from the center, but it slowed the spontaneous acivity in balls from the periphery of the SA node. An application of 2 mM Cs^+,1muM UL-SF 49 or 3muM ZD7288, which has been reported to block hyperpolarization-activated current (I_f), decreased pacemaker slope and spontaneous rate of small balls of the SA node. The decrease was largest in balls from the periphery and least in balls from the center. These results suggest that I_<Ca> Plays an obligatory role in pacemaking in the center, whereas I_<Na> Plays a major role in pacemaking in the periphery, and that the contribution of I_f to spontaneous activity is greater in the periphery than in the center of the SA node. 4-aminopyridine (4-AP), which is known to block a population of K^+ current, caused a marked prolongation of action potential and a slowing of spontaneous rate in the periphery, but it accelerated spontaneous activity in the center of the SA node. This suggests that 4-AP-sensitive currents are also involved in the heterogeneity of the electrical activity within the SA node.

Report

(3 results)
  • 1996 Annual Research Report   Final Research Report Summary
  • 1995 Annual Research Report
  • Research Products

    (37 results)

All Other

All Publications (37 results)

  • [Publications] Mark R.Boyett: "Ionic basis of the chronotropic effect of acetylcholine on the rabbit sinoatrial node" Cardiovascular Research. 29. 867-878 (1995)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] Itsuo Kodama: "Regional differences in the response of the isolated sino-atrial nodeof the rabbit to vagal stimulation" Journal of Physiology. 495. 785-801 (1996)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] Haruo Honjo: "Correlation between electrical activity and the size of rabbit sino-atrial node cells" Journal of Physiology. 496. 795-808 (1996)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] Ei-ichi Watanebe: "Inactivation of calcium current is involved in overdrive suppression of rabbit sino-atrial node cells" American Journal of Physiology. 271. H2097-H2107 (1996)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] Haruo Honjo: "The density of the TTX-sensitive Na^+ current and the hperpolarization-activated current in rabbit sinoatrial node cells depends on cell size" Journal of Physiology. 491P. 154 (1996)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] Muhammad Nikmaram: "The Na^+ current plays an important role in pacemaker activity in the periphery,but not in centre,of the rabbit sinoatrial node" Journal of Physiology. 491P. 154 (1996)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] Junji Toyama: "Computer simulation of the electrotonic modulation of pacemaker activity in the sinoatrial node by atrial muscle" Journal of Electrocardiology. 28 (Suppl.). 212-215 (1996)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] Mitsuru Yamamoto: "Extracellular electrical activity of the sinoatrial node in rabbit hearts" Environmental Medicine. 40. 78-81 (1996)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] Haruo Honjo: "Heterogeniety of the transient outward current in rabbit sinoatrial node cells" Environmental Medicine. 40 (in press). (1996)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] 児玉逸雄: "洞房結節における迷走神経刺激効果の部位差と2相性陰性変時作用" 環境医学研究所年報. 47. 130-134 (1996)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] 本荘晴朗: "洞房結節細胞の形態および機能の多様性に関する研究:TTX感受性Na^+電流と細胞の大きさとの関係" 環境医学研究所年報. 47. 135-137 (1996)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] 鈴木良子: "洞房結節細胞ペースメーカー機構の結節内部位差:Na^+電流L型Ca^<2+>電流及び過分極活性化電流の寄与" Japanese Circulation Journal. 60 (Suppl.). 123 (1996)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] 鈴木良子: "4-aminopyridineが洞房結節活動電位波形に及ぼす作用:結節内部位差について" Japanese Journal of Electrocardiology. 16. 517 (1996)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] Muhammad Nikmaram: "Variation in the effects of Cs^+,UL-SF 49 and ZD 7288 within the sino-atrial node" American Journal of Physiology. (in press). (1997)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] Itsuo Kodama: "Regional differences in the role of Ca^<2+> and Na^+ currents in pacemaker activity in the sinoatrial node" American Journal of Physiology. (in press). (1997)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] Mark R.Boyett: "Ionic basis of the chronotropic effect of acetylcholine on the rabbit sinoatrial node" Cardiovascular Research. 29. 867-878 (1995)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] Itsuo Kodama: "Regional differences in the response of the isolated sino-atrial node of the rebbit to vagal stimulation" Journal of Physiology. 495. 785-801 (1996)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] Haruo Honjo: "Correlation between electrical activity and the size of rabbit sino-atrial node cells" Journal of Physiology. 496. 795-808 (1996)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] Ei-ichi Watanabe: "Inactivation of calcium current is involved in overdrive suppression of rabbit sino-atrial node cells" American Journal of Physiology. 271. H2097-H2107 (1996)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] Haruo Honjo: "The density of the TTX-sensitive Na^+ current and the hperpolarization-activated current in rabbit sinoatrial node cells depends on cell size" Journal of physiology. 491P. 154 (1996)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] Muhammad Nikmaram: "The Na^+ current plays an important role inpacemaker activity in the periphery, but not in center, of the rabbit sinoatrial node" Journal of Physiology. 491P. 154 (1996)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] Junji Toyama: "Computer simulation of the electrotonic modulation of pacemaker activity in the sinoatrial node by atrial muscle" Journal of Electrocardiology. 28(Suppl.). 212-215 (1996)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] Mitsuru Yamamoto: "Extracellular electrical activity of the sinoatrial node in rabbit hearts" Environmental Medicine. 40. 78-81 (1996)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] Haruo Honjo: "Heterogeniety of the transient outward current in rabbit sinoatrial node cells" Environmental Medicine. 40(in press). (1996)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] Muhammad Nikmaram: "Variation in the effects of Cs^+, UL-SF 49 and ZD 7288 within the sino-atrial node" American Journal of Physiology. (in press). (1997)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] Itsuo Kodama: "Regional differences in the role of Ca^<2+> and Na^+ currents in pacemaker activity in the sinoatrial node" American Journal of Physiology. (in press). (1997)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] Itsuo Kodama: "Regional differences in the response of the isolated sino-atrial node of the rabbit to vagal stimulation" Journal of Physiology. 495. 785-801 (1996)

    • Related Report
      1996 Annual Research Report
  • [Publications] Haruo Honjo: "Correlation between electrical activity and the size of rabbit sino-atrial node cells" Journal of Physiology. 496. 795-808 (1996)

    • Related Report
      1996 Annual Research Report
  • [Publications] Ei-ichi Watanabe: "Inactivation of calcium current is involved in overdrive suppression of rabbit sinoatrial node cells" American Journal of Physiology. 271. H2097-H2107 (1996)

    • Related Report
      1996 Annual Research Report
  • [Publications] Muhammad Nikmaram: "Variation in the effects of Cs^+,UL-SF 49 and ZD 7288 within the sino-atrial node" American Journal of Physiology. (in press). (1997)

    • Related Report
      1996 Annual Research Report
  • [Publications] Itsuo Kodama: "Regional differences in the role of Ca^<2+> and Na^+ currents in pacemaker activity in the sinoatrial node" American Journal of Physiology. (in press). (1997)

    • Related Report
      1996 Annual Research Report
  • [Publications] 児玉逸雄: "洞房結節における迷走神経刺激効果の部位差と2相性陰性変時作用" 環境医学研究所年報. 47(in press). (1996)

    • Related Report
      1995 Annual Research Report
  • [Publications] 本荘晴朗: "洞房結節細胞の形態および機能の多様性に関する研究-TTX感受性Na+電流と細胞の大きさとの関係" 環境医学研究所年報. 47(in press). (1996)

    • Related Report
      1995 Annual Research Report
  • [Publications] Muhammad R. Nikmaram: "The Na+ current plays an importent role in pacemaker activity in the periphery, but not the centre, of the rabbit sinoatrial node" Journal of Physiology. (in press). (1996)

    • Related Report
      1995 Annual Research Report
  • [Publications] Haruo Honjo: "The density of the TTX-sensitive Na+current and the hyperpolarization-activated current in rabbit sinoatrial node cells depends on cell size" Journal of Physiology. (in press). (1996)

    • Related Report
      1995 Annual Research Report
  • [Publications] Mark R. Boyett: "Ionic basis of the chronotropic effect of acetylcholine on the rabbit sinoatrial node" Cardiovascular. Research. 29. 867-878 (1995)

    • Related Report
      1995 Annual Research Report
  • [Publications] Itsuo Kodama: "The effects of zatebradine(UF-SF49)on the negative chronotropic effects of actylcholine on the sinoatrial node" Environmental Medicine. 39. 69-72 (1995)

    • Related Report
      1995 Annual Research Report

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Published: 1995-04-01   Modified: 2016-04-21  

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