Human retinal pigment epithelial cells in culture possess A2-adenosine receptors

Zvi Friedman, Sean F. Hackett, Joel Linden, Peter A. Campochiaro

Research output: Contribution to journalArticlepeer-review

40 Scopus citations


Adenosine agonists cause a marked stimulation in cyclic AMP accumulation in whole human retinal pigment epithelial (RPE) cells in the presence of adenosine deaminase and papaverine, a phosphodiesterase inhibitor. N-Ethylcarboxamidoadenosine (NECA) stimulate cyclic AMP accumulation 16.1-fold above basal with an EC50 of 2.5 × 10-7 M. It is also an effective (1.9-fold) stimulator of adenylate cyclase activity in RPE membrane preparations and a modest (1.22-fold) stimulator in the presence of forskolin in RPE cell membranes prepared from freshly isolated porcine RPE. N6-Cyclopentyladenosine (CPA) and N6-phenylisopropyladenosine (PIA) also increase cyclic AMP levels with EC50s of 4.9 × 106 M (8.9-fold above basal) and 3.5 × 10-6 M (8.0-fold above basal) respectively. This potency order (NECA > PIA > CPA) is typical of A2-adenosine receptors. The relatively A1-selective agonist CPA and PIA, failed to decrease isoproterenol-stimulated cyclic AMP accumulation at concentrations ranging between 10-10 and 10-7 M indicating that RPE cells do not have A1-receptors which inhibit adenylate cyclase. Three adenosine receptor antagonists, BW-A1433U, 8-cyclopentyltheophylline and 8-sulfophenyltheophylline, blocked the NECA-induced stimulation of cyclic AMP accumulation with IC50s of 0.36 μM, 1.5 μM, and 75 μM respectively. Since alteration of cAMP levels has been demonstrated to affect several RPE functions, including cell migration, resorption of subretinal fluid, and phagocytosis, adenosine may play a significant regulatory role in RPE.

Original languageEnglish (US)
Pages (from-to)29-35
Number of pages7
JournalBrain research
Issue number1-2
StatePublished - Jul 17 1989
Externally publishedYes


  • A-adenosine receptor
  • Adenosine
  • Adenylate cyclase
  • Cyclic adenosine monophosphate
  • Purinergic receptor
  • Retinal pigment epithelium

ASJC Scopus subject areas

  • General Neuroscience
  • Molecular Biology
  • Clinical Neurology
  • Developmental Biology


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