Effects of IBMX on the rod ERG of the isolated perfused cat eye: antagonism with light, calcium or L-cis-diltiazem

Vision Res. 1991;31(7-8):1093-7. doi: 10.1016/0042-6989(91)90035-4.


Full-field electroretinograms (ERGs) were recorded from isolated cat eyes perfused through the ophthalmociliary artery with the cGMP-PDE inhibitor, 3-isobutylmethylxanthine (IBMX). Under dark-adapted conditions perfusion with IBMX resulted in reduced ERG b-wave amplitudes at low stimulus luminances and supernormal b-wave amplitudes at high stimulus luminances with reduced b-wave sensitivity; b-wave implicit times were more delayed at low than at high stimulus luminances. Presentation of a steady white background or high calcium fully reversed the supernormal amplitudes and partially reversed the delayed implicit times produced by IBMX. Rod ERG b-wave sensitivity, reduced with IBMX alone, was partially reversed with calcium but further reduced with background light. Perfusion with the cation channel blocker, L-cis-diltiazem, also reversed the supernormal amplitudes produced by IBMX but had no effect on implicit times or b-wave sensitivity. Possible mechanisms of action of these antagonists and clinical implications of these findings are considered.

Publication types

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

MeSH terms

  • 1-Methyl-3-isobutylxanthine / pharmacology*
  • Animals
  • Calcium / pharmacology
  • Cats
  • Dark Adaptation
  • Diltiazem / pharmacology*
  • Electroretinography / drug effects
  • In Vitro Techniques
  • Light
  • Photoreceptor Cells / drug effects
  • Photoreceptor Cells / physiology*


  • Diltiazem
  • Calcium
  • 1-Methyl-3-isobutylxanthine