title: Effect of adenosine receptor agonists on release of the nucleoside analogue [3H]formycin B from cultured smooth muscle DDT1 MF-2 cells.
abstract: Adenosine has receptor-mediated effects in a variety of cell types and is predominantly formed from ATP by a series of nucleotidase reactions. Adenosine formed intracellularly can be released by bidirectional nucleoside transport processes to activate cell surface receptors. We examined whether stimulation of adenosine receptors has a regulatory effect on transporter-mediated nucleoside release. DDT1 MF-2 smooth muscle cells, which possess nitrobenzylthioinosine-sensitive (ES) transporters as well as both adenosine A1 and A2 receptors, were loaded with the metabolically stable nucleoside analogue [3H]formycin B. N6-cyclohexyladenosine (CHA), a selective adenosine A1 receptor agonist, produced a concentration-dependent inhibition of [3H]formycin B release with an IC50 value of 2.7 microM. Further investigation revealed CHA interacts directly with nucleoside transporters with a Ki value of 3.3 microM. Neither 5'-N-ethylcarboxamidoadenosine (NECA), a mixed adenosine A1 and A2 receptor agonist, nor CGS 21680, a selective adenosine A2A receptor agonist, affected nucleoside release. We conclude that release of the nucleoside formycin B from DDT1 MF-2 cells is not regulated by adenosine A1 or A2 receptor activation.
authors.affiliation: Department of Pharmacology and Therapeutics, University of Manitoba, Winnipeg, Canada.
authors.forename: S L
authors.initials: SL
authors.lastname: Borgland
authors.forename: F E
authors.initials: FE
authors.lastname: Parkinson
mesh_terms: D000345:Affinity Labels; D000818:Animals; D002460:Cell Line; D006224:Cricetinae; D000242:Cyclic AMP / Q000096:biosynthesis; D005573:Formycins / Q000378:metabolism*; D008297:Male; D008647:Mesocricetus; D009130:Muscle, Smooth / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D058906:Purinergic P1 Receptor Agonists; D058915:Purinergic P1 Receptor Antagonists; D013868:Thioinosine / Q000031:analogs & derivatives / Q000378:metabolism; D014649:Vas Deferens / Q000166:cytology / Q000187:drug effects / Q000378:metabolism
chemical_list: D000345:Affinity Labels; D005573:Formycins; D058906:Purinergic P1 Receptor Agonists; D058915:Purinergic P1 Receptor Antagonists; C034561:formycin B; D013868:Thioinosine; D000242:Cyclic AMP; C001789:4-nitrobenzylthioinosine