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Pflügers Archiv

, Volume 414, Issue 2, pp 171–177 | Cite as

Calcium-dependent slow outward current in visceral primary afferent neurones of the rabbit

  • K. Morita
  • Y. Katayama
Excitable Tissues and Central Nervous Physiology

Abstract

Slow outward currents were recorded from voltage-clamped neurones in nodose ganglia excised from rabbits. In the majority of Type C neurones, a short depolarizing command pulse evoked a slow outward tail current (ISAH) with a decay time constant ranging from 0.5 to 2 s. TheISAH was due to an increase in membrane conductance to K+ because its reversal potential was approximately equal to the Nernst potential for K+. TheISAH was reversibly blocked by removal of external Ca2+ or by Ca2+ antagonists. A Ca2+ ionophore, A23187, produced an outward current which was similar to theISAH. TheISAH was resistant to tetraethylammonium and depressed by Ba2+, whereas it was not affected by Cs+ and 4-aminopyridine. TheISAH was initially augmented and subsequently depressed by apamin (1–10 nM) and (+)-tubocurarine (100–600 μM). It is concluded that theISAH in visceral primary neurones may be due to a long-lasting increase in K+ conductance caused by an increase in the concentration of intracellular Ca2+, resulting from Ca2+ entry during the depolarizing command pulse.

Key words

Calcium-dependent potassium channel Nodose ganglion Rabbit Voltage-clamp Slow outward tail current Slow after-hyperpolarization 

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Copyright information

© Springer-Verlag 1989

Authors and Affiliations

  • K. Morita
    • 1
  • Y. Katayama
    • 1
  1. 1.Department of Autonomic Physiology, Medical Research InstituteTokyo Medical and Dental UniversityChiyoda-ku, TokyoJapan

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