title: Nitric oxide interacts with oxygen free radicals to evoke the release of adenosine and adenine nucleotides from rat hippocampal slices.
abstract: The present study examined some possible mechanisms underlying the previously demonstrated release of adenosine by nitric oxide (NO) donors. Perfusion with the NO-donor S-nitroso-N-acetyl penicillamine (SNAP; 300 microM) led to a significant increase in the release of [3H]purines from both unstimulated and electrically stimulated hippocampal slices prelabeled with [3H]adenine. The NO-donor also evoked the release of endogenous ATP and ADP from unstimulated slices and, when combined with electrical stimulation, the release of ATP, AMP and adenosine. The SNAP-induced [3H]purine release was calcium-dependent, but not affected by the glutamate receptor antagonists MK-801 ((+)-5-methyl-10,11-dihydro-5H-dibenzo[a, d]-cyclohepten-5,10-imine;100 nM) and CNQX (6-cyano-7-nitroquinoxaline-2,3-dione; 10 microM). Zaprinast (5 microM), an inhibitor of the cyclic GMP-dependent phosphodiesterase and 8-Br-cyclic GMP (0.01-1 mM) failed to evoke the release of purines, whereas generation of oxygen free radicals by xanthine plus xanthine oxidase did evoke purine release. Coperfusion of SNAP with the free radical scavengers superoxide dismutase (SOD; 60 microg/ml) and catalase (50 microg/ml) reduced or eliminated the ability of the NO-donor to enhance [3H]purine release, but the poly (ADP-ribosyl) synthetase (PARS) inhibitor benzamide (500 microM) did not affect it. These data indicate that NO interacts with superoxide, likely forming peroxynitrite, which subsequently acts to release adenosine and adenine nucleotides from hippocampal tissue.
authors.affiliation: Department of Physiology and Pharmacology, Section of Molecular Neuropharmacology, Karolinska Institute, S-171 77, Stockholm, Sweden.
authors.forename: R M
authors.initials: RM
authors.lastname: Broad
authors.forename: N
authors.initials: N
authors.lastname: Fallahi
authors.forename: B B
authors.initials: BB
authors.lastname: Fredholm
mesh_terms: D000227:Adenine Nucleotides / Q000378:metabolism*; D000241:Adenosine / Q000378:metabolism*; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D004558:Electric Stimulation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016166:Free Radical Scavengers / Q000494:pharmacology; D018698:Glutamic Acid / Q000378:metabolism; D006624:Hippocampus / Q000378:metabolism*; D066298:In Vitro Techniques; D009569:Nitric Oxide / Q000378:metabolism / Q000502:physiology*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D010396:Penicillamine / Q000031:analogs & derivatives / Q000494:pharmacology; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species / Q000502:physiology*; D026423:S-Nitroso-N-Acetylpenicillamine
chemical_list: D000227:Adenine Nucleotides; D004791:Enzyme Inhibitors; D016166:Free Radical Scavengers; D020030:Nitric Oxide Donors; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D017382:Reactive Oxygen Species; D009569:Nitric Oxide; D018698:Glutamic Acid; D026423:S-Nitroso-N-Acetylpenicillamine; D010396:Penicillamine; D000241:Adenosine