Adenosine inhibits calcium channel currents via A1 receptors on salamander retinal ganglion cells in a mini-slice preparation

J Neurochem. 2002 May;81(3):550-6. doi: 10.1046/j.1471-4159.2002.00832.x.


The effects of adenosine on high-voltage-activated calcium channel currents in tiger salamander retinal ganglion cells were investigated in a mini-slice preparation. Adenosine produced a concentration-dependent decrease in the amplitude of calcium channel current with a maximum inhibition of 26%. The effects of adenosine on calcium channel current were both time- and voltage-dependent. In cells dialyzed with GTP-gamma-s, adenosine caused a sustained and irreversible inhibition of calcium channel current, suggesting involvement of a GTP-binding protein. The inhibitory effect of adenosine on calcium channel current was blocked by the A1 antagonist 8-cyclopentyltheophylline (DPCPX, 1-10 microm), but not by the A2 antagonist 3-7-dimethyl-1-propargylxanthine (DMPX, 10 microm), and was mimicked by the A1 agonist N6-cyclohexyladenosine (CHA, 1 microm) but not by the A2 agonist 5'-(N-cyclopropyl) carbox-amidoadenosine (CPCA, 1 microm). Adenosine's inhibition of calcium channel current was not affected by the L-type calcium channel blocker nifedipine (5 microm). However, adenosine's inhibition of calcium channel current was reduced to approximately 10% after application of omega-conotoxin GVIA (1 microm), suggesting that adenosine inhibits N-type calcium channels. These results show that adenosine acts on an A1 adenosine receptor subtype via a G protein-coupled pathway to inhibit the component of calcium channel current carried in N-type calcium channels.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine / pharmacology*
  • Ambystoma
  • Animals
  • Calcium / metabolism
  • Calcium Channel Blockers / pharmacology
  • Calcium Channels / drug effects*
  • Calcium Channels / metabolism*
  • Dialysis
  • Fluorescent Dyes
  • Guanosine 5'-O-(3-Thiotriphosphate) / pharmacology
  • In Vitro Techniques
  • Patch-Clamp Techniques
  • Purinergic P1 Receptor Antagonists
  • Receptors, Purinergic P1 / metabolism*
  • Retinal Ganglion Cells / cytology
  • Retinal Ganglion Cells / drug effects
  • Retinal Ganglion Cells / metabolism*
  • Theobromine / analogs & derivatives*
  • Theobromine / pharmacology
  • Xanthines / pharmacology


  • Calcium Channel Blockers
  • Calcium Channels
  • Fluorescent Dyes
  • Purinergic P1 Receptor Antagonists
  • Receptors, Purinergic P1
  • Xanthines
  • Guanosine 5'-O-(3-Thiotriphosphate)
  • 3,7-dimethyl-1-propargylxanthine
  • 1,3-dipropyl-8-cyclopentylxanthine
  • Adenosine
  • Theobromine
  • Calcium