Reversibility and cation selectivity of the K+-Cl- cotransport in rat central neurons

Yasuhiro Kakazu, Soko Uchida, Takashi Nakagawa, Norio Akaike, Junichi Nabekura

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Abstract

The reversibility and cation selectivity of the K+-Cl- cotransporter (KCC), which normally extrudes Cl- out of neurons, was investigated in dissociated lateral superior olive neurons of rats using the gramicidin perforated patch technique. Intracellular Cl- activity (α[Cl-](i)) was maintained well below electrochemical equilibrium as determined from the extracellular Cl- activity and the holding potential, where the pipette and external solutions contained 150 mM K+ ([K+](pipette)) and 5 mM K+ ([K+](o)), respectively. Extracellular application of 1 mM furosemide or elevated [K+](o) increased α[Cl-](i). When the pipette solution contained 150 mM Cs+ ([Cs+](pipette)), α[Cl-](i) increased to a value higher than the passive α[Cl-](i). An increase of α[Cl-](i) with the [Cs+](pipette) was not due to the simple blockade of net KCC by the intracellular Cs+ since α[Cl-](i), with the pipette solution containing 75 mM Cs+ and 75 mM K+, reached a value between those obtained using the [K+](pipette) and the [Cs+](pipette). The higher-than-passive α[Cl-](i) with the [Cs+](pipette) was reduced by 1 mM furosemide, but not by 20 μM bumetanide or Na+-free external solution, indicating that the accumulation of [Cl-](i) in the [Cs+](pipette) was mediated by a KCC operating in a reversed mode rather than by Na+-dependent, bumetanide-sensitive mechanisms. Replacement of K+ in the pipette solution with either Li+ or Na+ mimicked the effect of Cs+ on α[Cl-](i). On the other hand, Rb+ mimicked K+ in the pipette solution. These results indicate that K+ and Rb+, but not Cs+, Li+, or Na+, can act as substrates of KCC in LSO neurons.

Original languageEnglish
Pages (from-to)281-288
Number of pages8
JournalJournal of Neurophysiology
Volume84
Issue number1
Publication statusPublished - Aug 9 2000

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Cations
Neurons
Bumetanide
Furosemide
Gramicidin
potassium-chloride symporters

All Science Journal Classification (ASJC) codes

  • Neuroscience(all)
  • Physiology

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Reversibility and cation selectivity of the K+-Cl- cotransport in rat central neurons. / Kakazu, Yasuhiro; Uchida, Soko; Nakagawa, Takashi; Akaike, Norio; Nabekura, Junichi.

In: Journal of Neurophysiology, Vol. 84, No. 1, 09.08.2000, p. 281-288.

Research output: Contribution to journalArticle

Kakazu, Y, Uchida, S, Nakagawa, T, Akaike, N & Nabekura, J 2000, 'Reversibility and cation selectivity of the K+-Cl- cotransport in rat central neurons', Journal of Neurophysiology, vol. 84, no. 1, pp. 281-288.
Kakazu, Yasuhiro ; Uchida, Soko ; Nakagawa, Takashi ; Akaike, Norio ; Nabekura, Junichi. / Reversibility and cation selectivity of the K+-Cl- cotransport in rat central neurons. In: Journal of Neurophysiology. 2000 ; Vol. 84, No. 1. pp. 281-288.
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