title: Extracellular Adenosine Diphosphate Ribose Mobilizes Intracellular Ca2+ via Purinergic-Dependent Ca2+ Pathways in Rat Pulmonary Artery Smooth Muscle Cells.
abstract: OBJECTIVE
  Adenosine diphosphate ribose (ADPR), a product of β-NAD+ metabolism generated by the multifunctional enzyme CD38, is recognized as a novel signaling molecule. The catalytic site of CD38 orients extracellularly or intracellularly, capable of generating ADPR outside and inside the cells. CD38-dependent pathways have been characterized in pulmonary artery smooth muscle cells (PASMCs); however the physiological function of extracellular ADPR is unclear.
  
  
  METHODS
  Ca2+ mobilizing and proliferative effects of extracellular ADPR were characterized and compared with the ATP-induced responses in rat PASMCs; and the expression of purinergic receptor (P2X and P2Y) subtypes were examined in pulmonary arteries.
  
  
  RESULTS
  ADPR elicited concentration-dependent increase in [Ca2+]i with a fast transient and a sustained phase in PASMCs. The sustained phase was abolished by Ca2+ removal and inhibited by the non-selective cation channel blocker SKF-96365, but was unaffected by TRPM2 antagonists or nifedipine. The purinergic receptor (P2X) antagonist pyridoxal-phosphate-6-azophenyl-2', 4'-disulfonate inhibited partially the transient and the sustained Ca2+ response, while the P2(XY) inhibitor suramin and the phospholipase C inhibitor U73122 abolished the sustained Ca2+ influx. The P2Y1 antagonist MRS2179 had no effect on the response. By contrast, ATP and ADP activated Ca2+ response exhibited a high and a low affinity component, and the pharmacological profile of ATP-induced Ca2+ response was distinctive from that of ADPR. BrdU incorporation assay showed that ADPR caused significant inhibition whereas ATP caused slight stimulation of PASMC proliferation. RT-PCR analysis found that almost all P2X and P2Y subtypes are expressed in PAs.
  
  
  CONCLUSIONS
  ADPR and ATP activate Ca2+ responses through different combinations of multiple purinergic receptor subtypes; and extracellular ADPR may exert an autocrine/paracrine action via purinergic receptors on PASMCs.
authors.forename: Chun
authors.initials: C
authors.lastname: Huang
authors.forename: Jinxing
authors.initials: J
authors.lastname: Hu
authors.forename: Krishna P
authors.initials: KP
authors.lastname: Subedi
authors.forename: Amanda H Y
authors.initials: AH
authors.lastname: Lin
authors.forename: Omkar
authors.initials: O
authors.lastname: Paudel
authors.forename: Pixin
authors.initials: P
authors.lastname: Ran
authors.forename: James S K
authors.initials: JS
authors.lastname: Sham
mesh_terms: D000246:Adenosine Diphosphate Ribose / Q000494:pharmacology*; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects*; D002478:Cells, Cultured; D004963:Estrenes / Q000494:pharmacology; D007093:Imidazoles / Q000494:pharmacology; D007477:Ions / Q000737:chemistry / Q000378:metabolism; D008297:Male; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D009543:Nifedipine / Q000494:pharmacology; D011651:Pulmonary Artery / Q000166:cytology / Q000378:metabolism; D058920:Purinergic P2X Receptor Antagonists / Q000494:pharmacology; D058921:Purinergic P2Y Receptor Antagonists / Q000494:pharmacology; D011760:Pyrrolidinones / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D058469:Receptors, Purinergic P2X / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D058472:Receptors, Purinergic P2Y1 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013498:Suramin / Q000494:pharmacology; D050053:TRPM Cation Channels / Q000378:metabolism; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D004963:Estrenes; D007093:Imidazoles; D007477:Ions; D058920:Purinergic P2X Receptor Antagonists; D058921:Purinergic P2Y Receptor Antagonists; D011760:Pyrrolidinones; D058469:Receptors, Purinergic P2X; D058472:Receptors, Purinergic P2Y1; D050053:TRPM Cation Channels; C557080:Trpm2 protein, rat; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; D000246:Adenosine Diphosphate Ribose; D013498:Suramin; D000255:Adenosine Triphosphate; D010738:Type C Phospholipases; C063159:1-(2-(3-(4-methoxyphenyl)propoxy)-4-methoxyphenylethyl)-1H-imidazole; D009543:Nifedipine; D002118:Calcium