title: Endogenously released ATP mediates shear stress-induced Ca2+ influx into pulmonary artery endothelial cells.
abstract: The mechanisms by which flow-imposed shear stress elevates intracellular Ca2+ in cultured endothelial cells (ECs) are not fully understood. Here we report finding that endogenously released ATP contributes to shear stress-induced Ca2+ responses. Application of flow of Hanks' balanced solution to human pulmonary artery ECs (HPAECs) elicited shear stress-dependent increases in Ca2+ concentrations. Chelation of extracellular Ca2+ with EGTA completely abolished the Ca2+ responses, whereas the phospholipase C inhibitor U-73122 or the Ca2+-ATPase inhibitor thapsigargin had no effect, which thereby indicates that the response was due to the influx of extracellular Ca2+. The Ca2+ influx was significantly suppressed by apyrase, which degrades ATP, or antisense oligonucleotide targeted to P2X4 purinoceptors. A luciferase luminometric assay showed that shear stress induced dose-dependent release of ATP. When the ATP release was inhibited by the ATP synthase inhibitors angiostatin or oligomycin, the Ca2+ influx was markedly suppressed but was restored by removal of these inhibitors or addition of extracellular ATP. These results suggest that shear stress stimulates HPAECs to release ATP, which activates Ca2+ influx via P2X4 receptors.
authors.affiliation: Department of Biomedical Engineering, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Kimiko
authors.initials: K
authors.lastname: Yamamoto
authors.forename: Takaaki
authors.initials: T
authors.lastname: Sokabe
authors.forename: Norihiko
authors.initials: N
authors.lastname: Ohura
authors.forename: Hideki
authors.initials: H
authors.lastname: Nakatsuka
authors.forename: Akira
authors.initials: A
authors.lastname: Kamiya
authors.forename: Joji
authors.initials: J
authors.lastname: Ando
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D043168:Angiostatins; D000970:Antineoplastic Agents / Q000494:pharmacology; D001081:Apyrase / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D009840:Oligomycins / Q000494:pharmacology; D010446:Peptide Fragments / Q000494:pharmacology; D010958:Plasminogen / Q000494:pharmacology; D011651:Pulmonary Artery / Q000166:cytology / Q000378:metabolism*; D011673:Pulsatile Flow / Q000502:physiology; D018048:Receptors, Purinergic P2 / Q000235:genetics / Q000378:metabolism*; D058848:Receptors, Purinergic P2X4; D013314:Stress, Mechanical
chemical_list: D000970:Antineoplastic Agents; D004791:Enzyme Inhibitors; D009840:Oligomycins; C548226:P2RX4 protein, human; D010446:Peptide Fragments; D018048:Receptors, Purinergic P2; D058848:Receptors, Purinergic P2X4; D043168:Angiostatins; D000255:Adenosine Triphosphate; D010958:Plasminogen; D001081:Apyrase; D002118:Calcium