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Extracellular Adenosine Diphosphate Ribose Mobilizes Intracellular Ca 2+ via Purinergic‐dependent Ca 2+ Pathway in Rat Pulmonary Artery Smooth Muscle Cells
Author(s) -
Huang Chun,
Hu Jinxing,
Subedi Krishna P.,
Lin Amanda H.Y.,
Sham James S.K.
Publication year - 2016
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.30.1_supplement.775.4
Subject(s) - extracellular , purinergic receptor , ryanodine receptor , adenosine , phospholipase c , chelerythrine , adenosine receptor antagonist , chemistry , biology , intracellular , biophysics , medicine , biochemistry , receptor , protein kinase c , signal transduction , adenosine receptor , agonist
Adenosine diphosphate ribose (ADPR), a product of β‐NAD + metabolism 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. Here we sought to characterize the Ca 2+ mobilizing and proliferative effects of extracellular ADPR and compared with the ATP‐induced responses in rat PASMCs. 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 IP 3 ‐receptor inhibitor xestospongin C caused a partial inhibition of the peak and the sustained phase, while ryanodine had no effect on the ADPR‐induced Ca response. 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 mRNA of most P2X and P2Y subtypes are expressed in PAs. In 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. Support or Funding Information This work was supported by NIH grants HL071835 and HL075134,, National Natural Science Foundation of China grant NSFC31371165, and Fujian Province “Hundred Experts Award”