Cl- channels in basolateral renal medullary membranes VI. Cl- conductance expression in Xenopus oocytes

L. Zimniak, W. B. Reeves, T. E. Andreoli

Research output: Contribution to journalArticle

9 Scopus citations

Abstract

Cl- channels from basolateral membranes of the mammalian thick ascending limb of Henle differ significantly, in certain of their functional characteristics, from Cl- channels in apical membranes of secretory epithelia such as trachea or small intestine and from certain Cl- channels in the central nervous system. Yet there is no sequence information available about basolateral thick ascending limb Cl- channels. As an initial step in the isolation of a Cl- channel from the thick ascending limb of Henle's loop, we attempted a functional expression of a Cl- conductance in oocytes from Xenopus laevis. Oocytes injected with mRNA isolated from the outer medulla of rabbit kidney had a membrane conductance, measured using a two- electrode voltage clamp, which was sixfold greater than in water-injected oocytes (9.05 ± 1.56 vs. 1.43 ± 0.15 μS, respectively). Ion substitution experiments showed the conductance in the RNA-injected oocytes to be Cl- selective. In addition, the Cl- channel blocker diphenylamine-2-carboxylate (1 mM) almost completely inhibited (79 ± 6%) the increased conductance seen in the RNA-injected oocytes. Fractionation of the mRNA by sucrose gradient centrifugation revealed that peak Cl- channel activity was expressed using an mRNA fraction of 1.8-3.2 kb in size. These results demonstrate that a membrane Cl- conductance can be expressed in X. laevis oocytes injected with size-selected fractions of mRNA from rabbit outer renal medulla.

Original languageEnglish (US)
Pages (from-to)F979-F984
JournalAmerican Journal of Physiology - Renal Fluid and Electrolyte Physiology
Volume263
Issue number5 32-5
DOIs
StatePublished - 1992
Externally publishedYes

Keywords

  • Xenopus oocytes
  • chloride channels
  • diphenylamine carboxylate
  • gene expression

ASJC Scopus subject areas

  • Physiology

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