Thiamine triphosphate activates an anion channel of large unit conductance in neuroblastoma cells

J Membr Biol. 1993 Dec;136(3):281-8. doi: 10.1007/BF00233667.


In neuroblastoma cells, the intracellular thiamine triphosphate (TTP) concentration was found to be about 0.5 microM, which is several times above the amount of cultured neurons or glial cells. In inside-out patches, addition of TTP (1 or 10 microM) to the bath activated an anion channel of large unit conductance (350-400 pS) in symmetrical 150 mM NaCl solution. The activation occurred after a delay of about 4 min and was not reversed when TTP was washed out. A possible explanation is that the channel has been irreversibly phosphorylated by TTP. The channel open probability (Po) shows a bell-shaped behavior as a function of pipette potential (Vp). Po is maximal for -25 mV < Vp < 10 mV and steeply decreases outside this potential range. From reversal potentials, permeability ratios of PCl/PNa = 20 and PCl/Pgluconate = 3 were estimated. ATP (5 mM) at the cytoplasmic side of the channel decreased the mean single channel conductance by about 50%, but thiamine derivatives did not affect unit conductance; 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (0.1 mM) increased the flickering of the channel between the open and closed state, finally leading to its closure. Addition of oxythiamine (1 mM), a thiamine antimetabolite, to the pipette filling solution potentiates the time-dependent inactivation of the channel at Vp = -20 mV but had the opposite effect at +30 mV. This finding corresponds to a shift of Po towards more negative resting membrane potentials. These observations agree with our previous results showing a modulation of chloride permeability by thiamine derivatives in membrane vesicles from rat brain.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / pharmacology
  • Adenosine Triphosphate / pharmacology
  • Animals
  • Cell Membrane Permeability / drug effects
  • Chloride Channels / drug effects*
  • Chloride Channels / metabolism
  • Electric Conductivity
  • Membrane Potentials
  • Mice
  • Neuroblastoma / metabolism*
  • Oxythiamine / pharmacology
  • Phosphorylation
  • Thiamine Triphosphate / pharmacology*
  • Tumor Cells, Cultured / metabolism


  • Chloride Channels
  • Oxythiamine
  • Thiamine Triphosphate
  • Adenosine Triphosphate
  • 4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid