Ionic mechanism of ouabain-induced swelling of leech Retzius neurons

Pflugers Arch. 2006 Apr;452(1):25-35. doi: 10.1007/s00424-005-0009-6. Epub 2005 Dec 10.

Abstract

By using electrophysiological and microfluorimetric methods, we found that leech Retzius neurons swell after inhibition of the Na(+)-K(+) pump by the cardiac glycoside ouabain. To explore the mechanism of this swelling, we measured the effect of ouabain on [Na(+)](i), [K(+)](i), and [Cl(-)](i), as well as on the membrane potential, by applying triple-barrelled ion-sensitive microelectrodes. As shown previously, ouabain induced a marked [Na(+)](i) increase, a [K(+)](i) decrease, and a membrane depolarization, and it also evoked an increase in [Cl(-)](i). The analysis of the data revealed a net uptake of NaCl, which quantitatively explained the ouabain-induced cell swelling. In the absence of extracellular Na(+) or Cl(-), NaCl uptake was excluded, and the cell volume remained unaffected. Likewise, NaCl uptake and, hence, cell swelling did not occur when the Na(+)-K(+) pump was inhibited by omitting bath K(+). Also, in K(+)-free solution, [Na(+)](i) increased and [K(+)](i) dropped, but [Cl(-)](i) slightly decreased, and after an initial, small membrane depolarization, the cells hyperpolarized for a prolonged period. It is concluded that the ouabain-induced NaCl uptake is caused by the depolarization of the plasma membrane, which augments the inwardly directed electrochemical Cl(-) gradient.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium / metabolism
  • Cell Membrane / metabolism
  • Chlorides / metabolism
  • Cytosol / drug effects
  • Enzyme Inhibitors / pharmacology*
  • Fura-2
  • Hirudo medicinalis
  • Membrane Potentials / drug effects
  • Neurons / drug effects*
  • Neurons / metabolism
  • Ouabain / pharmacology*
  • Potassium / metabolism
  • Sodium / metabolism
  • Sodium Chloride / metabolism*
  • Sodium-Potassium-Exchanging ATPase / antagonists & inhibitors*

Substances

  • Chlorides
  • Enzyme Inhibitors
  • Sodium Chloride
  • Ouabain
  • Sodium
  • Sodium-Potassium-Exchanging ATPase
  • Potassium
  • Calcium
  • Fura-2