Contribution of Na(+)-K(+)-Cl(-) cotransporter to high-[K(+)](o)- induced swelling and EAA release in astrocytes

Am J Physiol Cell Physiol. 2002 May;282(5):C1136-46. doi: 10.1152/ajpcell.00478.2001.

Abstract

We hypothesized that high extracellular K(+) concentration ([K(+)](o))-mediated stimulation of Na(+)-K(+)-Cl(-) cotransporter isoform 1 (NKCC1) may result in a net gain of K(+) and Cl(-) and thus lead to high-[K(+)](o)-induced swelling and glutamate release. In the current study, relative cell volume changes were determined in astrocytes. Under 75 mM [K(+)](o,) astrocytes swelled by 20.2 +/- 4.9%. This high-[K(+)](o)-mediated swelling was abolished by the NKCC1 inhibitor bumetanide (10 microM, 1.0 +/- 3.1%; P < 0.05). Intracellular (36)Cl(-) accumulation was increased from a control value of 0.39 +/- 0.06 to 0.68 +/- 0.05 micromol/mg protein in response to 75 mM [K(+)](o). This increase was significantly reduced by bumetanide (P < 0.05). Basal intracellular Na(+) concentration ([Na(+)](i)) was reduced from 19.1 +/- 0.8 to 16.8 +/- 1.9 mM by bumetanide (P < 0.05). [Na(+)](i) decreased to 8.4 +/- 1.0 mM under 75 mM [K(+)](o) and was further reduced to 5.2 +/- 1.7 mM by bumetanide. In addition, the recovery rate of [Na(+)](i) on return to 5.8 mM [K(+)](o) was decreased by 40% in the presence of bumetanide (P < 0.05). Bumetanide inhibited high-[K(+)](o)-induced (14)C-labeled D-aspartate release by ~50% (P < 0.05). These results suggest that NKCC1 contributes to high-[K(+)](o)-induced astrocyte swelling and glutamate release.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • 4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / metabolism
  • Animals
  • Aspartic Acid / metabolism
  • Astrocytes / drug effects
  • Astrocytes / metabolism*
  • Bumetanide / pharmacology
  • Cell Size
  • Cells, Cultured
  • Chlorides / metabolism*
  • Diuretics / pharmacology
  • Osmolar Concentration
  • Potassium / metabolism*
  • Rats
  • Rats, Sprague-Dawley
  • Sodium / metabolism*
  • Sodium Potassium Chloride Symporter Inhibitors
  • Sodium-Potassium-Chloride Symporters / metabolism*

Substances

  • Chlorides
  • Diuretics
  • Sodium Potassium Chloride Symporter Inhibitors
  • Sodium-Potassium-Chloride Symporters
  • Bumetanide
  • Aspartic Acid
  • Sodium
  • 4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid
  • Potassium