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1988 Fiscal Year Final Research Report Summary

Electrophysiological studies on single ionic channels in smooth muscle cell membrane.

Research Project

Project/Area Number 61480097
Research Category

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

Allocation TypeSingle-year Grants
Research Field General physiology
Research InstitutionNagoya University

Principal Investigator

TOMITA Tadao  Nagoya University, School of Medicine, 医学部, 教授 (50078763)

Co-Investigator(Kenkyū-buntansha) NAKAYAMA Shinsuke  Nagoya University, School of Medicine, 医学部, 助手 (30192230)
TOKUNO Hiroyuki  Nagoya University, School of Medicine, 医学部, 助手 (60155520)
Project Period (FY) 1986 – 1988
KeywordsSmooth muscle / Ionic channel / Patch-clamp / K-channel / Ca-channel / pH / カテコルアミン
Research Abstract

Excitability of cell membrane is determined by a relative intensity of inward and outward currents across the membrane, and in smooth muscle inward current is carried by Ca ions and outwaed current K ions. In this study, we have recorded channel current or membrane currents with so-called patch-clamp methods after isolating single cells. The most commonly odserved K-channel is activated by intracellular Ca, but calmodulin is not involved in this process. Its gating mechanism is affected by many other factors, such as membrane potential, pH, and ATP. Intracellular acidification decreases, while alkalinization increases channel activity. It was also found that this channel is involved in the inhibitory action of catecholamines,likely to be mediated by an increase in intracellular Ca concentrations. Ca-channel current was also increased by intracellular alkalinization. In the porcine coronary artery, which has predominantly L-type Ca channels,Ca-channel current was increased by activatio of -adrenergic receptors. Since forskolin, which directly activates adenylate cyclase, had the similar effect to catecholamines, it is considered that -action is mediated by intracellular cyclic AMP. It is, however, necessary to find out the physiological significance of the potentiation of Ca current by activation of -receptors, which ptoduces relaxation.

  • Research Products

    (11 results)

All Other

All Publications (11 results)

  • [Publications] Takai,A.;Tomita,T.: Journal of Physiology.381. 65-75 (1986)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Chihara,S.;Tomita,T.: British Journal of Pharmacology.91. 789-798 (1987)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Tokuno,H.;Tomita,T.;: European Journal of Pharmacology.141. 131-133 (1987)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Bulbring,E.;Tomita,T.: Pharmacological Reviews.39. 49-96 (1987)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Gonda,H.;Baba,K.;Satake,T.;Takagi,K.;Tomita,T.: Pulmonary Pharmacology.1. 7-13 (1988)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Tomita,T.: Japanese Journal of Physiology.38. 1-18 (1988)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Chihara, S.; Tomita, T.: "Mechanical and electrical responses to -adrenoceptor activation in the circular muscle of quinea-pig stomach." British Journal of Pharmacology.91. 789-798 (1987)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Tokuno, H.; Tomita, T.: "Collagenase eliminates the electrical responses of smooth muscle to catecholamines." European Journal of Pharmacology.141. 131-133 (1987)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Bulbring, E.; Tomita, T.: "Catecholamine action on smooth muscle." Pharmacological Reviews.39. 49-96 (1987)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Gonda, H.; Baba, K.; Satake, T.; Takagi, K.; Tomita, T.: "The dissociation constant of verapamil estimated from its effect on Ca concentration-tension curves in guinea-pig tracheal muscle." Pulmonary Pharmacology.1. 7-13 (1988)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Tomita, T.: "Ionic channels in smooth muscle studied with patch-clamp methods." Japanese Journal of Physiology.38. 1-18 (1988)

    • Description
      「研究成果報告書概要(欧文)」より

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Published: 1990-03-20  

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