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On the mechanism of slow calcium channel block in heart

  • Excitable Tissues and Central Nervous Physiology
  • Letters and Notes
  • Published:
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Abstract

  1. 1.

    D600 (methoxyverapamil, 2×10−6 M) has little activity when it is applied during a rest interval. Its ability to depress Isi and contraction is much reduced when the muscle is rested.

  2. 2.

    Upon each activation the blockade of the slow channel increases until the use-dependent increase of blockade equals the diastolic removal, thus resulting in a frequency-dependent steady-state blockade.

  3. 3.

    Removal of block during a variable rest interval at various holding potentials is the faster the more negative the holding potential and gets slower in the more positive potential range. This process can be described by two voltage-dependent time constants (τ1, τ2).

Similarities in the action of D600 on the si-channel to the action of local anaesthetics on the Na+-channel in nerve and heart are pointed out.

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Author notes

  1. T. F. McDonald

    Present address: Department of Physiology and Biophysics, Dalhousie University, Halifax, N.S., Canada

Authors and Affiliations

  1. II. Physiologisches Institut der Universität des Saarlandes, 6650, Homburg/Saar, Federal Republic of Germany

    T. F. McDonald, D. Pelzer & W. Trautwein

Authors
  1. T. F. McDonald
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  2. D. Pelzer
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  3. W. Trautwein
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supported by the Deutsche Forschungsgemeinschaft, SFB 38, project G1

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McDonald, T.F., Pelzer, D. & Trautwein, W. On the mechanism of slow calcium channel block in heart. Pflugers Arch. 385, 175–179 (1980). https://doi.org/10.1007/BF00588699

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  • DOI: https://doi.org/10.1007/BF00588699

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