Involvement of adenosine A1 receptors in upregulation of nitric oxide by acyclic nucleotide analogues.
Acyclic nucleoside phosphonates are a novel class of virostatics effective against replication of both DNA-viruses and retroviruses. They are synthetic analogues of natural nucleotide monophosphates, and purine derivatives thus represent counterparts of AMP. Mono- and di-phosphorylated species are analogues of natural ADP and ATP, respectively. A number of these compounds are endowed with immunostimulatory and immunomodulatory potential. We investigated whether their augmenting effect on the interferon-gamma-primed production of nitric oxide (NO) by murine macrophages is mediated by purinoceptors. The test compounds comprise alterations at the N(6)-group of the heterocyclic base, i.e., adenine or 2,6-diaminopurine, and at the N(9)-side chain, represented by 9-[2-(phosphonomethoxy)ethyl] and 9-[2-(phosphonomethoxy)propyl] moieties: 9-[2-(phosphonomethoxy)propyl]adenine [(R)-PMPA; tenofovir], N(6)-cyclopropyl-(R)-9-[2-(phosphonomethoxy)propyl]2,6-diaminopurine [N(6)-cyclopropyl-(R)-PMPDAP], N(6)-cyclopentyl-(R)-9-[2-(phosphonomethoxy)propyl]2,6-diaminopurine [N(6)-cyclopentyl-(R)-PMPDAP], N(6)-dimethylaminoethyl-(R)-9-[2-(phosphonomethoxy)propyl]2,6-diaminopurine [N(6)-dimethylaminoethyl-(R)-PMPDAP], N(6)-isobutyl-9-[2-(phosphonomethoxy)ethyl]2,6-diaminopurine (N(6)-isobutyl-PMEDAP), N(6)-cyclopentyl-9-[2-(phosphonomethoxy)ethyl]2,6-diaminopurine (N(6)-cyclopentyl-PMEDAP), N(6)-cyclooctyl-9-[2-(phosphonomethoxy)ethyl]2,6-diaminopurine (N(6)-cyclooctyl-PMEDAP), and N(6)-cyclohexylmethyl-9-[2-(phosphonomethoxy)ethyl]2,6-diaminopurine (N(6)-cyclohexylmethyl-PMEDAP). The cells were cultured in the presence of interferon-gamma (5000 pg/ml) and test compounds (2-50 microM). Formation of nitrites was determined after 24 h using Griess reagent. It was inhibited by specific and nonspecific antagonists of adenosine A(1) receptors (IC(50) for 8-cyclopentyl-1,3-dipropylxanthine [CPX] was approximately 10 microM), while all other purine P(1) and purine P(2) receptor antagonists remained ineffective to suppress the NO-synergistic effect of acyclic nucleoside phosphonates.
Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, Vídenská 1083, 142 20 Prague 4, Czech Republic. zidekz@biomed.cas.cz
Zdenĕk
Z
Zídek
Eva
E
Kmonícková
Antonín
A
Holý
D058916:Adenosine A1 Receptor Antagonists; D000818:Animals; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005260:Female; D017737:Macrophages, Peritoneal / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D009569:Nitric Oxide / Q000096:biosynthesis*; D009712:Nucleotides, Cyclic / Q000737:chemistry / Q000494:pharmacology*; D043682:Receptor, Adenosine A1 / Q000378:metabolism*; D011983:Receptors, Purinergic / Q000502:physiology*; D015854:Up-Regulation / Q000187:drug effects* / Q000502:physiology
D058916:Adenosine A1 Receptor Antagonists; D009712:Nucleotides, Cyclic; D043682:Receptor, Adenosine A1; D011983:Receptors, Purinergic; D009569:Nitric Oxide