April 2010
Volume 51, Issue 13
Free
ARVO Annual Meeting Abstract  |   April 2010
The Role of Endothelin B in Endothelin-1 Induced Rat Optic Nerve Head Astrocyte Proliferation and Ca2+ Signaling
Author Affiliations & Notes
  • J. A. Murphy
    Ophthalmology,
    Dalhousie University, Halifax, Nova Scotia, Canada
  • M. L. Archibald
    Physiology & Biophysics,
    Dalhousie University, Halifax, Nova Scotia, Canada
  • W. H. Baldridge
    Anat/Neuro/Ophthal -Tupper Bldg,
    Dalhousie University, Halifax, Nova Scotia, Canada
  • B. C. Chauhan
    Ophthalmology & Visual Sciences,
    Dalhousie University, Halifax, Nova Scotia, Canada
  • Footnotes
    Commercial Relationships  J.A. Murphy, None; M.L. Archibald, None; W.H. Baldridge, None; B.C. Chauhan, None.
  • Footnotes
    Support  Canadian Institute of Health grant MOP-57851, Dalhousie Medical Research Foundation Postdoctoral Fellowship (JM).
Investigative Ophthalmology & Visual Science April 2010, Vol.51, 2099. doi:https://doi.org/
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      J. A. Murphy, M. L. Archibald, W. H. Baldridge, B. C. Chauhan; The Role of Endothelin B in Endothelin-1 Induced Rat Optic Nerve Head Astrocyte Proliferation and Ca2+ Signaling. Invest. Ophthalmol. Vis. Sci. 2010;51(13):2099. doi: https://doi.org/.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose: : The goal of this research was to characterize the influence of endothelin-1 (ET-1) on rat optic nerve head astrocyte (ONHA) proliferation and Ca2+ signaling in cells lacking functional endothelin B (ETB) receptors.

Methods: : Optic nerve head astrocytes (ONHAs) were isolated from adult wild type (WT) and transgenic spotted lethal (TSL) rats which lack functional ETB receptors. Astrocyte specificity was determined immunohistochemically with positive labeling for glial fibrillary acidic protein (GFAP), and negative labeling for A2B5 (a marker for Type II astrocytes located outside the optic nerve head) and myelin basic protein (MBP). The mitogenic effects of ET-1 at concentrations of 10-7, or 10-9 M or vehicle were investigated for 48 or 72 hrs in TSL and WT ONHAs. To investigate intracellular calcium ([Ca2+]i) in ONHAs, cells were loaded with fura-2 AM calcium indicator dye.

Results: : The specificity of the cultured cells as ONHAs was confirmed with positive labeling for GFAP, and negative labeling for A2B5 and MBP. In TSL cells, ET-1 induced proliferation was significantly blunted at 48 hrs (by 37% at 10-7 M, p = 0.072; and by 33% at 10-9 M, p = 0.039) and 72 hrs (by 117% at 10-7 M, p = 0.004; and by 100% at 10-9 M) compared with WT cells. There was, however, significant proliferation of TSL cells with ET-1 compared to vehicle compared with WT cells; at 48 hrs (by 36% at 10-7 M, p<0.001; and by 25% at 10-9 M, p = 0.002) and at 72 hrs (by 30% at 10-7 M, p = 0.002; and by 30% at 10-9 M, p = 0.003). Increases in ONHA [Ca2+]i following ET-1 exposure were significantly greater in TSL cells (by 20% at 10-7 M, p=0.001; and by 48% at 10-8 M, p=0.001). ET-1 at 10-9 M did not alter [Ca2+]i.

Conclusions: : These findings indicate that (1) ET-1 induces proliferation of ONHAs which lack functional ETB receptors, (2) that this proliferation is reduced compared to cells which possess both ETB and ETA receptors, and (3) that absence of functional ETB receptors increases ET-1 induced [Ca2+]i.

Keywords: optic nerve • astrocyte • proliferation 
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