Calcium-dependent release of arachidonic acid in response to purinergic receptor activation in airway epithelium.
The effect of purinergic receptor agonists on arachidonic acid release was investigated in [3H]arachidonic acid-prelabeled human airway epithelial cells. Exposure of bronchial epithelial BEAS39 cells to extracellular ATP resulted in a marked release of unesterified [3H]arachidonic acid with maximal effect observed within 60-90 s. [3H]diacylglycerol and [3H]phosphatidic acid accumulated in parallel with [3H]arachidonic acid. ATP-stimulated [3H]arachidonic acid release with a K0.5 of 9 +/- 2 microM and UTP was equipotent; no effect was observed with P2Y- or P2X-purinergic receptor agonists or with adenosine. Similar results were obtained with primary cultures of normal human nasal epithelium, CF/T43 and HBE1 airway epithelial cell lines derived from a cystic fibrosis patient and from a normal donor, respectively, and HT-29 human colon carcinoma cells. ATP stimulated inositol phosphate formation in BEAS39 cells with a concentration dependence identical to that for [3H]arachidonic acid release. The effect of ATP on both [3H]arachidonic acid release and inositol phosphate formation was equally inhibited by pertussis toxin. The Ca2+ ionophore A-23187 mimicked the effects of ATP or UTP on arachidonic acid release, and a marked inhibitory effect was observed with thapsigargin. The protein kinase C inhibitor staurosporine partially inhibited ATP-stimulated [3H]arachidonic acid release. These data are consistent with the hypothesis that phospholipase A2 activation is secondary to P2U-purinergic receptor stimulation of D-myoinositol 1,4,5-trisphosphate production and calcium mobilization from intracellular stores.
Lazarowski
E R
ER
Department of Medicine, University of North Carolina, Chapel Hill 27599.
Boucher
R C
RC
Harden
T K
TK
D000255:Adenosine Triphosphate / Q000494:pharmacology; D016718:Arachidonic Acid / Q000378:metabolism*; D002118:Calcium / Q000494:pharmacology*; D002478:Cells, Cultured; D003110:Colonic Neoplasms / Q000378:metabolism; D004075:Diglycerides / Q000378:metabolism; D004847:Epithelial Cells; D004848:Epithelium / Q000378:metabolism; D004951:Esterification; D006801:Humans; D007295:Inositol Phosphates / Q000378:metabolism; D050356:Lipid Metabolism; D009711:Nucleotides / Q000494:pharmacology; D010712:Phosphatidic Acids / Q000378:metabolism; D011983:Receptors, Purinergic / Q000502:physiology*; D012137:Respiratory System / Q000166:cytology / Q000378:metabolism*; D014407:Tumor Cells, Cultured
D004075:Diglycerides; D007295:Inositol Phosphates; D009711:Nucleotides; D010712:Phosphatidic Acids; D011983:Receptors, Purinergic; D016718:Arachidonic Acid; D000255:Adenosine Triphosphate; D002118:Calcium