title: Bovine adrenal endothelial cells express nucleoside transporters nonregulated by protein kinases A and C.
abstract: The present investigation characterizes the nucleoside transporters in bovine adrenomedullary endothelial cells and their possible regulation by the action of protein kinases A and C to establish comparisons with the nucleoside transport system in chromaffin cells. The nucleoside transport proved to be a nitrobenzylthioinosine (NBTI)-sensitive facilitated-diffusion system with high affinity for adenosine. These endothelial cells had a high density of nucleoside transporters (660,000 +/- 130,000 transporters/ cell), measured by NBTI binding, and the efficiency was close to 2 adenosine molecules internalized transporter-1.s-1. The stimulation of the cells with bradykinin and P1,P4-di(adenosine-5')tetraphosphate, which raise the intracellular Ca2+ concentration, did not modulate the adenosine transport. When the cells were stimulated with signals coupled to adenosine 3',5'-cyclic monophosphate intracellular production, such as norepinephrine and isoproterenol, the adenosine transport was not modified. Furthermore, the treatment of the cells with direct activators of both protein kinases A and C had no effect on adenosine transport, in contrast to that reported in chromaffin cells.
authors.affiliation: Department of Biochemistry, Facultad de Veterinaria, Universidad Complutense, Madrid, Spain.
authors.forename: R P
authors.initials: RP
authors.lastname: Sen
authors.forename: L
authors.initials: L
authors.lastname: Sobrevía
authors.forename: E G
authors.initials: EG
authors.lastname: Delicado
authors.forename: D
authors.initials: D
authors.lastname: Yudilevich
authors.forename: M T
authors.initials: MT
authors.lastname: Miras-Portugal
mesh_terms: D000241:Adenosine / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000311:Adrenal Glands / Q000166:cytology / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002352:Carrier Proteins / Q000378:metabolism*; D002417:Cattle; D002478:Cells, Cultured; D017868:Cyclic AMP-Dependent Protein Kinases / Q000502:physiology*; D004727:Endothelium / Q000166:cytology / Q000378:metabolism; D011493:Protein Kinase C / Q000502:physiology*; D013868:Thioinosine / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology
chemical_list: D002352:Carrier Proteins; D013868:Thioinosine; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; C001789:4-nitrobenzylthioinosine; D000241:Adenosine