Pflügers Archiv

, Volume 388, Issue 3, pp 255–260 | Cite as

Potassium current during the pacemaker depolarization in rabbit sinoatrial node cell

  • Kaoru Yanagihara
  • Hiroshi Irisawa
Excitable Tissues and Central Nervous Physiology

Abstract

Voltage clamp experiments were carried out on the rabbit sinoatrial (S-A) node. The delayed outward current in the voltage range between −60 mV and −22 mV almost disappeared in the presence of 5 mM Ba2+. The slow inward current and the hyperpolarization-activated current remained unaffected. In the absence of the time-dependent potassium current the S-A node cell generated spontaneous action potentials, provided that the membrane was hyperpolarized by constant outward current. Therefore it seems unlikely that the potassium current plays an essential role in generating the pacemaker potential in the S-A node. The time course of the potassium current (iK) during the cardiac cycle was calculated using equations simulating the kinetics ofiK. According to this computation, the change ofiK.in the S-A node is small during pacemaker depolarization. It is proposed that the gradual decay of potassium conductance is less important for the development of the pacemaker potential than the contribution of the slow inward current.

Key words

S-A node Pacemaker potential Potassium current Slow inward current Barium ion 

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Copyright information

© Springer-Verlag 1980

Authors and Affiliations

  • Kaoru Yanagihara
    • 1
  • Hiroshi Irisawa
    • 1
  1. 1.National Institute for Physiological SciencesOkazakiJapan

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