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Pflügers Archiv

, Volume 439, Issue 6, pp 700–704 | Cite as

Inhibition of apamin-sensitive K+ current by hypoxia in adult rat adrenal chromaffin cells

  • J. Lee
  • W. Lim
  • S.-Y. Eun
  • S.J. Kim
  • J. Kim
Original Article
  • 30 Downloads

Abstract

The effect of hypoxia on small-conductance Ca2+-activated K+ current was investigated in a study of adult rat adrenomedullary chromaffin cells (AMCs), which were maintained in short-term culture. The nystatin-perforated, whole-cell patchclamp technique was used to study the effect of hypoxia with minimum perturbation of the intracellular milieu. Under voltage-clamp conditions, acute hypoxia (P O2≅25 mmHg) suppressed the whole-cell outward currents of more than half the AMCs (24/46). This suppression was eliminated after application of apamin (400 nM), a selective inhibitor of small-conductance Ca2+-activated K+ current (I SK(Ca)) (n=5), suggesting that an apamin-sensitive component of whole-cell currents is suppressed during hypoxia. In contrast to I SK(Ca), Ca2+ current (I Ca) (n=10) was not affected by hypoxia. Finally, under current-clamp conditions, hypoxia reversibly depolarized the resting membrane potential of adult AMCs (34/40). Apamin, however, eliminated the hypoxia-induced depolarization (400 nM) (7/8), suggesting that hypoxic depolarization is related to the suppression of I SK(Ca). From the above results, we conclude that adult AMCs are sensitive to hypoxia, and that I SK(Ca) contributes to the hypoxia-induced suppression of whole-cell outward current and depolarization of the resting membrane potential in adult AMCs.

Adrenomedullary chromaffin cell Apamin Hypoxia Hypoxic depolarization Small-conductance Ca2+-activated K+ current Whole-cell patch clamp 

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Copyright information

© Springer-Verlag 2000

Authors and Affiliations

  • J. Lee
    • 1
  • W. Lim
    • 1
  • S.-Y. Eun
    • 1
  • S.J. Kim
    • 2
  • J. Kim
    • 1
  1. 1.Department of Physiology and Biophysics, Seoul National University College of Medicine, 28 Yongon-dong, Chongno-gu, Seoul, 110–799Korea
  2. 2.Department of Physiology, Kangwon National University, College of Medicine, Chunchon, Kangwon-doKorea

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