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 μM [3H]adenine to label adenine nucleotide pools. Metabolic stress with the glycolytic inhibitor iodoacetic acid (IAA, 5 mM) increased tritium release by 63% (P < 0.01), relative to cells treated with buffer alone. The IAA-induced increase was blocked by the nucleoside transport inhibitor nitrobenzylthioinosine (1 μM), 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% (P < 0.05). This increase was blocked by the A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (10 μM). Treatment of cells with UTP (100 μM), histamine (100 μM), or phorbol-12-myristate-13-acetate (PMA, 10 μM) 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.

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   |wiki=    Wicri/Canada
   |area=    ParkinsonCanadaV1
   |flux=    Main
   |étape=   Exploration
   |type=    RBID
   |clé=     ISTEX:4FC2ADCBA661D4DD95133E0A6442C2B02E2DE317
   |texte=   Stimulation of nucleoside efflux and inhibition of adenosine kinase by A1 adenosine receptor activation
}}