title: Characterization of P2X7 purinergic receptors and their function in rat lacrimal gland.
abstract: OBJECTIVE
  To characterize the effects of P2X(7) purinergic receptors on lacrimal gland function.
  
  
  METHODS
  P2X(7) purinergic receptors were identified by RT-PCR, Western blot analysis, and immunofluorescence techniques. Rat lacrimal gland acini were isolated by collagenase digestion. Acini were incubated with the fluorescent indicator molecule fura 2, and [Ca(2+)](i) was measured by a fluorescence imaging system. Protein secretion was measured with a fluorescence assay system. Activation of ERK 1/2 was determined by Western blot analysis with an antibody against phosphorylated (active) ERK 1/2.
  
  
  RESULTS
  P2X(7) receptors were present in the lacrimal gland by RT-PCR and Western blot analysis. These receptors were located in the membranes of acinar and ductal cells and the cytoplasm of acinar cells. Activation of P2X(7) receptors with (benzoylbenzoyl)adenosine 5'-triphosphate increased [Ca(2+)](i), peroxidase secretion, and ERK 1/2 activation, each of which was inhibited by the P2X(7) receptor inhibitors Brilliant Blue G or A 438079.
  
  
  CONCLUSIONS
  P2X(7) purinergic receptors are present in rat lacrimal gland and when stimulated increase [Ca(2+)](i), protein secretion, and ERK 1/2 activation.
authors.affiliation: Schepens Eye Research Institute, Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts 02114, USA. robin.hodges@schepens.harvard.edu
authors.forename: Robin R
authors.initials: RR
authors.lastname: Hodges
authors.forename: Joanna
authors.initials: J
authors.lastname: Vrouvlianis
authors.forename: Marie A
authors.initials: MA
authors.lastname: Shatos
authors.forename: Darlene A
authors.initials: DA
authors.lastname: Dartt
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D004789:Enzyme Activation; D019084:Fluorescent Antibody Technique, Indirect; D016257:Fura-2 / Q000378:metabolism; D007765:Lacrimal Apparatus / Q000378:metabolism*; D008297:Male; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D010766:Phosphorylation; D051381:Rats; D017207:Rats, Sprague-Dawley; D018048:Receptors, Purinergic P2 / Q000378:metabolism*; D058486:Receptors, Purinergic P2X7; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: C546470:P2rx7 protein, rat; D018048:Receptors, Purinergic P2; D058486:Receptors, Purinergic P2X7; C535149:Mapk1 protein, rat; D019950:Mitogen-Activated Protein Kinase 1; D002118:Calcium; D016257:Fura-2