title: ATP receptor regulation of adenylate cyclase and protein kinase C activity in cultured renal LLC-PK1 cells.
abstract: In cultured intact LLC-PK1 renal epithelial cells, a nonhydrolyzable ATP analogue, ATP gamma S, inhibits AVP-stimulated cAMP formation. In LLC-PK1 membranes, several ATP analogues inhibit basal, GTP-, forskolin-, and AVP-stimulated adenylate cyclase activity in a dose-dependent manner. The rank order potency of inhibition by ATP analogues suggests that a P2y type of ATP receptor is involved in this inhibition. The compound ATP gamma S inhibits agonist-stimulated adenylate cyclase activity in solubilized and in isobutylmethylxanthine (IBMX) and quinacrine pretreated membranes, suggesting that ATP gamma S inhibition occurs independent of AVP and A1 adenosine receptors and of phospholipase A2 activity. The ATP gamma S inhibition of AVP-stimulated adenylate cyclase activity is not affected by pertussis toxin but is attenuated by GDP beta S, suggesting a possible role for a pertussis toxin insensitive G protein in the inhibition. Exposure of intact LLC-PK cells to ATP gamma S results in a significant increase in protein kinase C activity. However, neither of two protein kinase C inhibitors (staurosporine and H-7) prevents ATP gamma S inhibition of AVP-stimulated adenylate cyclase activity, suggesting that this inhibition occurs by a protein kinase C independent mechanism. These findings suggest the presence of functional P2y purinoceptors coupled to two signal transduction pathways in cultured renal epithelial cells. The effect of P2y purinoceptors to inhibit AVP-stimulated adenylate cyclase activity may be mediated, at least in part, by a pertussis toxin insensitive G protein.
authors.affiliation: Medical Service, Denver Veterans Affairs Medical Center, Colorado 80220.
authors.forename: R J
authors.initials: RJ
authors.lastname: Anderson
authors.forename: R
authors.initials: R
authors.lastname: Breckon
authors.forename: B S
authors.initials: BS
authors.lastname: Dixon
mesh_terms: D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000032:analysis; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D000262:Adenylyl Cyclases / Q000032:analysis*; D001127:Arginine Vasopressin / Q000494:pharmacology; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000096:biosynthesis; D019204:GTP-Binding Proteins / Q000502:physiology; D007668:Kidney / Q000201:enzymology*; D011493:Protein Kinase C / Q000032:analysis*; D011983:Receptors, Purinergic / Q000187:drug effects / Q000502:physiology*
chemical_list: D011983:Receptors, Purinergic; D001127:Arginine Vasopressin; C022571:adenosine 5'-O-(3-thiotriphosphate); D000255:Adenosine Triphosphate; D000242:Cyclic AMP; D011493:Protein Kinase C; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D019204:GTP-Binding Proteins; D000262:Adenylyl Cyclases