title: ATP inhibits Mg(2+) uptake in MDCT cells via P2X purinoceptors.
abstract: Nucleotides have diverse effects on water and electrolyte reabsorption within the distal tubule of the nephron. As the distal tubule is important in control of renal Mg(2+) balance, we determined the effects of ATP on cellular Mg(2+) uptake in this segment. The effects of ATP on immortalized mouse distal convoluted tubule (MDCT) cells were studied by measuring Mg(2+) uptake with fluorescence techniques. The mean basal Mg(2+) uptake rate was 165 +/- 6 nM/s. ATP inhibited basal Mg(2+) uptake and hormone-stimulated Mg(2+) entry by 40%. Both P2X (P2X1-P2X5 subtypes) and P2Y2 receptor subtypes were identified in MDCT cells using differential RT-PCR. Activation of both receptor subtypes with selective agonists increased intracellular Ca(2+) concentration, P2X purinoceptors by ionotropic-gated channels, and P2Y receptors via G protein-mediated intracellular Ca(2+) release. The more relatively selective P2X agonists [beta,gamma-methylene ATP (beta,gamma-Me-ATP) and 2'- and -3'-O-(4-benzoyl-benzoyl)-ATP] inhibited arginine vasopressin (AVP)- and parathyroid hormone (PTH)-mediated Mg(2+) uptake whereas agonists more selective for P2Y purinoceptors (UTP, ADP, and 2-methylthio-ATP) were without effect. Removal of extracellular Ca(2+) diminished beta,gamma-Me-ATP-mediated increase in intracellular Ca(2+) and inhibition of AVP-stimulated Mg(2+) entry. We conclude from this information that ATP inhibited Mg(2+) uptake in MDCT cells through P2X purinoceptors expressed in this distal convoluted tubule cell line.
authors.affiliation: Department of Medicine, University of British Columbia, Vancouver Hospital and Health Sciences Centre, Vancouver, British Columbia, Canada V6T 1Z3.
authors.forename: L J
authors.initials: LJ
authors.lastname: Dai
authors.forename: H S
authors.initials: HS
authors.lastname: Kang
authors.forename: D
authors.initials: D
authors.lastname: Kerstan
authors.forename: G
authors.initials: G
authors.lastname: Ritchie
authors.forename: G A
authors.initials: GA
authors.lastname: Quamme
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D001127:Arginine Vasopressin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D002461:Cell Line, Transformed; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D015232:Dinoprostone / Q000494:pharmacology; D007213:Indomethacin / Q000494:pharmacology; D007686:Kidney Tubules, Distal / Q000378:metabolism*; D007700:Kinetics; D008274:Magnesium / Q000378:metabolism*; D051379:Mice; D009711:Nucleotides / Q000494:pharmacology; D010281:Parathyroid Hormone / Q000494:pharmacology; D012333:RNA, Messenger / Q000032:analysis; D018048:Receptors, Purinergic P2 / Q000235:genetics / Q000502:physiology*; D058469:Receptors, Purinergic P2X; D058472:Receptors, Purinergic P2Y1; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment
chemical_list: D016861:Cyclooxygenase Inhibitors; D009711:Nucleotides; C546383:P2ry1 protein, mouse; D010281:Parathyroid Hormone; D012333:RNA, Messenger; D018048:Receptors, Purinergic P2; D058469:Receptors, Purinergic P2X; D058472:Receptors, Purinergic P2Y1; D001127:Arginine Vasopressin; D000255:Adenosine Triphosphate; D008274:Magnesium; D015232:Dinoprostone; D002118:Calcium; D007213:Indomethacin