Stimulation of nucleoside efflux and inhibition of adenosine kinase by A1 adenosine receptor activation
| Autor: | Jonathan D. Geiger, Christopher J. D. Sinclair, P. Nicholas Shepel, Fiona E. Parkinson |
|---|---|
| Rok vydání: | 2000 |
| Předmět: |
Pharmacology
Adenosine biology Receptors Purinergic P1 Membrane Proteins Biological Transport Nucleoside Transport Proteins Adenosine kinase Transport inhibitor Biochemistry Adenosine receptor Molecular biology Adenosine A1 receptor Adenine nucleotide Cricetinae Tumor Cells Cultured biology.protein medicine Animals Adenosine kinase activity Carrier Proteins Adenosine Kinase Nucleoside medicine.drug |
| Zdroj: | Biochemical Pharmacology. 59:477-483 |
| ISSN: | 0006-2952 |
| DOI: | 10.1016/s0006-2952(99)00350-0 |
| Popis: | Adenosine is produced intracellularly during conditions of metabolic stress and is an endogenous agonist for four subtypes of G-protein linked receptors. Nucleoside transporters are membrane-bound carrier proteins that transfer adenosine, and other nucleosides, across biological membranes. We investigated whether adenosine receptor activation could modulate transporter-mediated adenosine efflux from metabolically stressed cells. DDT1 MF-2 smooth muscle cells were incubated with 10 microM [3H]adenine to label adenine nucleotide pools. Metabolic stress with the glycolytic inhibitor iodoacetic acid (1AA, 5 mM) increased tritium release by 63% (P0.01), relative to cells treated with buffer alone. The IAA-induced increase was blocked by the nucleoside transport inhibitor nitrobenzylthioinosine (1 microM), indicating that the increased tritium release was primarily a purine nucleoside. HPLC verified this to be [3H]adenosine. The adenosine A1 receptor selective agonist N6-cyclohexyladenosine (CHA, 300 nM) increased the release of [3H]purine nucleoside induced by IAA treatment by 39% (P0.05). This increase was blocked by the A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (10 microM). Treatment of cells with UTP (100 microM), histamine (100 microM), or phorbol-12-myristate-13-acetate (PMA, 10 microM) also increased [3H]purine nucleoside release. The protein kinase C inhibitor chelerythrine chloride (500 nM) inhibited the increase in [3H]purine nucleoside efflux induced by CHA or PMA treatment. The adenosine kinase activity of cells treated with CHA or PMA was found to be decreased significantly compared with buffer-treated cells. These data indicated that adenosine A1 receptor activation increased nucleoside efflux from metabolically stressed DDT1 MF-2 cells by a PKC-dependent inhibition of adenosine kinase activity. |
| Databáze: | OpenAIRE |
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