Pflügers Archiv

, Volume 410, Issue 1–2, pp 83–91 | Cite as

Alinidine modifies the pacemaker current in sheep Purkinje fibers

  • Dirk J. Snyders
  • Pierre-Paul Van Bogaert
Excitable Tissues and Central Nervous Physiology

Abstract

(1) The “specific bradycardic agent” alinidine reduces the slope of the diastolic depolarization in sinoatrial tissue and Purkinje fibers. In short Purkinje fibers of sheep, alinidine (28 μM) decreased the pacemaker current by a dual action. The voltage dependence ofif activation was shifted in the hyperpolarizing direction by 7.8±0.6 mV (n=18,p<0.001) and the conductance of the fully activated\(\bar i_{\text{f}}\) current was reduced to 73±2% (n=18,p<0.001) of its control value. These effects were reversible and dose-dependent. (2) Ionophoretic injections of alinidine caused reversible reductions of the diastolic depolarization rate and simultaneous transient hyperpolarizing shifts of theif activation range. (3) Some prolongation of the action potential duration was observed at 28 μM and more pronounced at higher concentration. This was presumably the consequence of a reduction by alinidine of outward repolarizing current carried by the background inward rectifier and plateau currentix. (4) The action of alinidine onif resulted in a slower activation of a reduced fraction of the pacemaker current at the maximal diastolic potential level. This explains the decrease of the diastolic depolarization rate observed in Purkinje fibers.

Key words

Alinidine Bradycardic agent Purkinje fibers Diastolic depolarization Pacemaker current Ionophoresis 

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Copyright information

© Springer-Verlag 1987

Authors and Affiliations

  • Dirk J. Snyders
    • 1
  • Pierre-Paul Van Bogaert
    • 1
  1. 1.Laboratory for Electrophysiology, Department of PhysiologyUniversity of Antwerp (R.U.C.A.)AntwerpBelgium

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