Agonist Activity of 2- And 5'-substituted Adenosine Analogs and Their N6-cycloalkyl Derivatives at A1- And A2-adenosine Receptors Coupled to Adenylate Cyclase

Biochem Pharmacol. 1992 Mar 3;43(5):1089-93. doi: 10.1016/0006-2952(92)90616-q.

Abstract

The activity of N6-cycloalkyl derivatives of adenosine, 2-chloroadenosine, 5'-chloroadenosine and N-ethylcarboximidoadenosine (NECA) and of 2-fluoroadenosine and 5-methylthioadenosines were compared at the A1-adenosine receptor inhibitory to adenylate cyclase in rat fat cell membranes and at the A2A-adenosine receptors stimulatory to adenylate cyclase in rat PC12 cell membranes. The N6-cycloalkyl derivatives in all cases were more potent (4- to 23-fold) than the parent compound at the A1 receptor, and were less potent (1.6- to 11-fold) than the parent compound at the A2A receptor. N6-Cyclopentyl-5'-chloroadenosine was the most selective agonist (900-fold) for the A1 receptor, while 2-fluoroadenosine was the only agonist with some selectivity (4.8-fold) for the A2A receptor. 5'-Methylthioadenosine was a weak agonist at both adenosine receptors. A 2-fluoro derivative of 5'-methylthioadenosine was somewhat more potent. Affinities of these analogs for inhibition of binding of radioligands to rat brain A1 and A2A receptors are presented.

MeSH terms

  • Adenosine / analogs & derivatives*
  • Adenylyl Cyclase Inhibitors
  • Adenylyl Cyclases / metabolism*
  • Animals
  • Cerebral Cortex / drug effects*
  • Cerebral Cortex / metabolism
  • Fibroblasts / drug effects
  • Fibroblasts / metabolism
  • Humans
  • PC12 Cells / drug effects
  • Rats
  • Receptors, Purinergic / drug effects*
  • Receptors, Purinergic / metabolism

Substances

  • Adenylyl Cyclase Inhibitors
  • Receptors, Purinergic
  • Adenylyl Cyclases
  • Adenosine