Extracellular Adenosine Diphosphate Ribose Mobilizes Intracellular Ca 2+ via Purinergic-Dependent Ca 2+ Pathways in Rat Pulmonary Artery Smooth Muscle Cells

Chun Huang, Jinxing Hu, Krishna P. Subedi, Amanda H.Y. Lin, Omkar Paudel, Pixin Ran, James S.K. Sham

Research output: Contribution to journalArticle

Abstract

Background/Aims: 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: Ca 2+ 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 [Ca 2+ ] i with a fast transient and a sustained phase in PASMCs. The sustained phase was abolished by Ca 2+ 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 Ca 2+ response, while the P2(XY) inhibitor suramin and the phospholipase C inhibitor U73122 abolished the sustained Ca 2+ influx. The P2Y1 antagonist MRS2179 had no effect on the response. By contrast, ATP and ADP activated Ca 2+ response exhibited a high and a low affinity component, and the pharmacological profile of ATP-induced Ca 2+ 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. Conclusion: ADPR and ATP activate Ca 2+ responses through different combinations of multiple purinergic receptor subtypes; and extracellular ADPR may exert an autocrine/paracrine action via purinergic receptors on PASMCs.

Original languageEnglish (US)
Pages (from-to)2043-2059
Number of pages17
JournalCellular Physiology and Biochemistry
Volume37
Issue number5
DOIs
StatePublished - Nov 1 2015

Keywords

  • Adenosine diphosphate ribose
  • Ca mobilization
  • Pulmonary arterial smooth muscle cells
  • Purinergic receptors

ASJC Scopus subject areas

  • Physiology

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