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Pflügers Archiv

, Volume 434, Issue 4, pp 413–421 | Cite as

Membrane currents in immature oocytes of the Rana perezi frog

  • I. Ivorra
  • Andrés Morales
ORIGINAL ARTICLE

Abstract

 Immature oocytes of the Rana perezi frog were studied electrophysiologically to see if some of the unusual ionic channels found in Xenopus oocytes were also expressed in these cells. Growing oocytes showed a fairly linear current/voltage relationship (from –200 to +60 mV), whereas fully grown cells had several voltage-dependent conductances. Depolarizing pulses elicited a potassium current blocked by tetraethylammonium (TEA) and two kinetically different Ca2+-dependent Clcurrents (ICl(Ca)), both sensitive to niflumic acid. ICl(Ca), which have not been previously observed in Rana immature oocytes, were also found in response to acetylcholine or rabbit serum superfusion or intracellular injection of Ca2+. In addition, three different Clcurrents were activated in these cells by hyperpolarization: (1) a transient inward current dependent on a critical intracellular Ca2+ concentration; (2) an inward rectifier Clcurrent, which was Ca2+ independent; and (3) a high threshold (over –140 mV), slow Clcurrent, blocked by several divalent cations, 4,4′-diisothiocyanatostilbene-2,2′-disulphonic acid (DIDS) and 4-acetamido-4-isothiocyanatostilbene-2,2′-disulphonic acid (SITS). The presence of most of these infrequent currents in immature oocytes of several frogs and toads suggests that they are not merely the result of random genomic expression but a programmed decision, probably related to a definite functional role.

Key words Immature oocytes Rana perezi Membrane currents Electrophysiology Calcium-dependent chloride channels Hyperpolarization-activated chloride channels Potassium channels 

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Copyright information

© Springer-Verlag Berlin Heidelberg 1997

Authors and Affiliations

  • I. Ivorra
    • 1
  • Andrés Morales
    • 1
  1. 1.Departamento de Fisiología, Universidad de Alicante, E-03080 Alicante, SpainES

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