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 language | English |
|---|---|
| Pages (from-to) | 281-288 |
| Number of pages | 8 |
| Journal | Journal of Neurophysiology |
| Volume | 84 |
| Issue number | 1 |
| Publication status | Published - Aug 9 2000 |
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All Science Journal Classification (ASJC) codes
- Neuroscience(all)
- Physiology
Cite this
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 journal › Article
}
TY - JOUR
T1 - Reversibility and cation selectivity of the K+-Cl- cotransport in rat central neurons
AU - Kakazu, Yasuhiro
AU - Uchida, Soko
AU - Nakagawa, Takashi
AU - Akaike, Norio
AU - Nabekura, Junichi
PY - 2000/8/9
Y1 - 2000/8/9
N2 - 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.
AB - 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.
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UR - http://www.scopus.com/inward/citedby.url?scp=0033930643&partnerID=8YFLogxK
M3 - Article
C2 - 10899203
AN - SCOPUS:0033930643
VL - 84
SP - 281
EP - 288
JO - Journal of Neurophysiology
JF - Journal of Neurophysiology
SN - 0022-3077
IS - 1
ER -