May 2007
Volume 48, Issue 13
Free
ARVO Annual Meeting Abstract  |   May 2007
Manganese-Enhanced MRI Studies of Intraretinal Dyshomeostasis
Author Affiliations & Notes
  • B. A. Berkowitz
    Wayne State Univ Sch of Med, Detroit, Michigan
    Anatomy & Cell Biology and Ophthalmology,
  • R. Roberts
    Wayne State Univ Sch of Med, Detroit, Michigan
    Anatomy & Cell Biology,
  • H. Luan
    Wayne State Univ Sch of Med, Detroit, Michigan
    Anatomy & Cell Biology,
  • D. Bissig
    Wayne State Univ Sch of Med, Detroit, Michigan
    Anatomy & Cell Biology,
  • B. V. Bui
    Department of Optometry and Vision Sciences, The University of Melbourne, Parkville, Australia
  • A. J. Vingrys
    Department of Optometry and Vision Sciences, The University of Melbourne, Parkville, Australia
  • M. Gradianu
    Wayne State Univ Sch of Med, Detroit, Michigan
    Anatomy & Cell Biology,
  • Footnotes
    Commercial Relationships B.A. Berkowitz, None; R. Roberts, None; H. Luan, None; D. Bissig, None; B.V. Bui, None; A.J. Vingrys, None; M. Gradianu, None.
  • Footnotes
    Support NIH Grant EY013831 (BAB), JDRF (BAB), NH&MRC 400127 (BVB) and 350224 (AJV)
Investigative Ophthalmology & Visual Science May 2007, Vol.48, 113. doi:https://doi.org/
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    • Get Citation

      B. A. Berkowitz, R. Roberts, H. Luan, D. Bissig, B. V. Bui, A. J. Vingrys, M. Gradianu; Manganese-Enhanced MRI Studies of Intraretinal Dyshomeostasis. Invest. Ophthalmol. Vis. Sci. 2007;48(13):113. doi: https://doi.org/.

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

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Abstract

Purpose:: To test the hypothesis that uptake of manganese, detected with manganese-enhanced MRI (MEMRI), is a sensitive and non-toxic metric of intraretinal ion dyshomeostasis as demonstrated following suppression of retinal Na-K ATPase activity with ouabain.

Methods:: To assess choroidal contribution, high resolution images were collected on 5 light adapted rats before and after Gd-DTPA injection i.v. To assess toxicity, ERGs were collected over an 8 log unit range of exposures (-6.1 to 2.2 log scot cd.s/m2) on 6 dark adapted (>12 hrs) rats before and after (4 hrs, 7 days) injection of MnCl2. Waveforms were collected (4 kHz, 0.3-1000 Hz) with corneal and scleral electrodes (Ag-AgCl) with a tail ground. Retinal layer-specific ion demand and retinal thickness were non-invasively and simultaneously measured from high resolution MEMRI data 4 hrs after MnCl2 (44 mg/kg,i.p.) injection. Two light adapted groups were studied with MEMRI: 5 control rats given phosphate buffered saline (PBS, 3 µl) intravitreally 20 hrs prior to MnCl2 injection, and 5 experimental rats given PBS+ouabain (0.55mM/3µl) intravitreally 20 hrs prior to MnCl2 injection). .

Results:: Comparing pre and post-Gd-DTPA images allowed for an estimate of choroidal thickness (65.5 + 7.6 mm (n = 5)) and a demonstration of a minimal choroidal contribution to intraretinal analysis. The ERG showed no effect on photoreceptor a-wave and post-receptor b-wave at either observation time (0 v 4 hrs or 7 days). After ouabain injection, receptor and post-receptor uptake of manganese was subnormal (P < 0.05).

Conclusions:: Uptake of systemically administered and non-toxic dose of manganese appears to provide a powerful approach for measuring alterations in intraretinal ion homeostasis.

Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • NaK ATPase • choroid 
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