Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.17.3.2 (xanthine oxidase)
 8,383 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

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.
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PMID:Nitric oxide interacts with oxygen free radicals to evoke the release of adenosine and adenine nucleotides from rat hippocampal slices. 1086 5

P-selectin and circulating xanthine oxidase are involved in the process of neutrophil infiltration into the lung associated with acute pancreatitis. This study investigated the mediators that trigger the upregulation of P-selectin in this process. Pancreatitis was induced in rats by intraductal administration of 5% sodium taurocholate. P-selectin expression was measured using radiolabeled antibodies. Neutrophil infiltration and PAF levels were also evaluated. The role of superoxide radical, H(2)O(2), or the enzyme poly (ADP-ribose) synthetase (PARS) on these processes was determined in groups of animals treated with the corresponding inhibitors. Pancreatitis was associated with an increase in P-selectin expression in the lung. Inhibition of PARS or H(2)O(2) abrogated P-selectin upregulation, PAF generation, and neutrophil recruitment. Superoxide dismutation prevented neutrophil recruitment and PAF generation, but had no effect on P-selectin expression. We conclude that during acute pancreatitis, upregulation of P-selectin in the pulmonary endothelium is triggered by H(2)O(2) and PARS activity.
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PMID:H(2)O(2) and PARS mediate lung P-selectin upregulation in acute pancreatitis. 1088 59