Intracellular spermine confers rectification on rat calcium-permeable AMPA and kainate receptors

J Physiol. 1995 Jul 15;486 ( Pt 2)(Pt 2):297-303. doi: 10.1113/jphysiol.1995.sp020812.


1. Whole-cell recordings were made from cerebellar granule cells cultured in high-K+ medium to induce expression of Ca(2+)-permeable AMPA receptors. Current-voltage (I-V) plots of agonist-evoked responses showed varying degrees of inward rectification, but became linear within 5-10 min. 2. Recombinant Ca(2+)-permeable kainate receptors, composed of GluR6(Q)/KA-2 subunits, exhibited rectifying whole-cell I-V plots that became linear in outside-out patches. 3. Loss of rectification in granule cells was prevented by including 100 microM spermine in the pipette; the degree of rectification was then correlated with Ca2+ permeability. 4. Spermine also prevented loss of rectification in patches containing GluR6(Q)/KA-2 receptors (IC50, 1.7 microM). 5. We suggest that spermine, or a similar cellular constituent, may act as a cytoplasmic factor conferring inward rectification on Ca(2+)-permeable non-NMDA receptors, and that 'washout' of this factor underlies the observed loss of rectification.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium / metabolism*
  • Cells, Cultured
  • Cerebellum / cytology
  • Cerebellum / metabolism
  • Intracellular Membranes / metabolism
  • Permeability
  • Rats
  • Rats, Sprague-Dawley
  • Receptors, AMPA / drug effects
  • Receptors, AMPA / metabolism*
  • Receptors, Kainic Acid / drug effects
  • Receptors, Kainic Acid / metabolism*
  • Recombinant Proteins
  • Spermine / physiology*


  • Receptors, AMPA
  • Receptors, Kainic Acid
  • Recombinant Proteins
  • Spermine
  • Calcium