title: Differential effects of prostaglandin E2-sensitive receptors on contractility of human ocular cells that regulate conventional outflow.
abstract: OBJECTIVE
  The goal of this study was to functionally compare prostaglandin E2 (PGE2)-sensitive receptors in human primary cells involved in conventional outflow.
  
  
  METHODS
  The expression profile of prostaglandin (PG) receptors in primary cultures of human trabecular meshwork (TM) and Schlemm's canal (SC) cells were determined by quantitative-PCR. The functional activities of endogenous PGE2-sensitive receptors were evaluated using subtype-selective agonists and antagonists with cell impedance technology.
  
  
  RESULTS
  Agonist-sensitive EP1, EP2, and EP4 receptors were present in TM cells, all increasing cell stiffness (or contractility) in a dose-dependent manner. Rank order of efficacy (Emax) for agonists in TM cells were EP1 greater than EP2 greater than EP4 with EC50 1.1 μM, 0.56 μM, and 0.1 μM, respectively, and no functional EP3 receptors were found. Of the four EP receptor subtypes active in SC cells, EP1 and EP3 receptor activation increased cell stiffness, while EP2 and EP4 agonists dose-dependently decreased cell stiffness 47% and 23% with EC50 values of 170 nM and 69 nM, respectively. Consistent with these observations, the Rho kinase inhibitor Y-27632 decreased cell impedance (stiffness) of TM and SC cells (∼60%), while Rho GTPase activator thrombin caused cell impedance to increase in both cell types (168%-190%).
  
  
  CONCLUSIONS
  Cell impedance positively correlates with cellular stiffness/contractility. Because EP2/4 receptors caused decreased cell stiffness in SC, but not in TM cells, both receptors appear to mediate IOP lowering via changes in SC cell stiffness in the conventional outflow pathway.
authors.affiliation: Department of Biological Sciences, Allergan, Inc., Irvine, California 92612, USA. wang_jenny@allergan.com
authors.forename: Jenny W
authors.initials: JW
authors.lastname: Wang
authors.forename: David F
authors.initials: DF
authors.lastname: Woodward
authors.forename: W Daniel
authors.initials: WD
authors.lastname: Stamer
mesh_terms: D000577:Amides / Q000494:pharmacology; D002478:Cells, Cultured; D015232:Dinoprostone / Q000378:metabolism / Q000494:pharmacology; D004548:Elasticity / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D016133:Polymerase Chain Reaction; D011725:Pyridines / Q000494:pharmacology; D011982:Receptors, Prostaglandin / Q000819:agonists / Q000187:drug effects / Q000378:metabolism*; D014129:Trabecular Meshwork / Q000187:drug effects / Q000502:physiology*
chemical_list: D000577:Amides; D004791:Enzyme Inhibitors; D011725:Pyridines; D011982:Receptors, Prostaglandin; C108830:Y 27632; D015232:Dinoprostone
keywords: Schlemm's canal; cell impedance; conventional outflow; prostaglandin E2 receptors; trabecular meshwork