December 2002
Volume 43, Issue 13
ARVO Annual Meeting Abstract  |   December 2002
Calcium Waves in Isolated Müller Cells Do Not Require an Internally Propagated Signal
Author Affiliations & Notes
  • SA Keirstead
    Ophthalmology University of Minnesota Minneapolis MN
  • JM Reifel Saltzberg
    Ophthalmology University of Minnesota Minneapolis MN
  • Footnotes
    Commercial Relationships   S.A. Keirstead, None; J.M. Reifel Saltzberg, None. Grant Identification: NIH Grant EY11736, Research to Prevent Blindness unrestricted grant to Department of Ophthalmology
Investigative Ophthalmology & Visual Science December 2002, Vol.43, 671. doi:
  • Views
  • Share
  • Tools
    • Alerts
      This feature is available to authenticated users only.
      Sign In or Create an Account ×
    • Get Citation

      SA Keirstead, JM Reifel Saltzberg; Calcium Waves in Isolated Müller Cells Do Not Require an Internally Propagated Signal . Invest. Ophthalmol. Vis. Sci. 2002;43(13):671.

      Download citation file:

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

  • Supplements

Abstract: : Purpose: Purinergic agonists evoke a wave-like increase in intracellular calcium ion concentration ([Ca2+]i) in isolated tiger salamander Müller cells This response occurs first in the distal/soma region and later in the endfoot. The purpose of this study was to determine whether these calcium waves are mediated by an internally propagated signal or if they are due to some inherent delay in the response in the endfoot region. Methods: Müller cells were enzymatically and mechanically dissociated from retinas of larval tiger salamanders and loaded with the calcium-sensitive dye Fura-2 AM. Cells were plated onto a coverslip-bottomed perfusion chamber which was placed on the stage of an inverted fluorescence microscope equipped with a computer-controlled filter wheel and digital camera. Fluorescence ratioes were measured in selected regions and plotted versus time. ATP (10-100 microM), 2-methylthio ATP (2MeSATP; 0.5 microM) and MRS2179 (500 microM) were applied either to the bath or locally by pressure ejection with a micropipette. Tetramethyl rhodamine (0.35%) was included in the pipette to monitor the distribution of the ejected solution. Results: Local application of ATP to either the distal region or endfoot of single Müller cells resulted in an increase in ([Ca2+]i) in the region to which ATP was applied. Thus, responses in either the distal region or endfoot region were localized and were not propagated to other regions of the cells. Localized application of the P2Y1 receptor antagonist MRS2179 to the endfoot of Müller cells inhibited responses to bath-applied 2MeSATP in the endfoot while the distal and somatic region of the cells responded as in the control situation. When the shaft connecting the soma and endfoot of Müller cells was transected, the endfoot retained the ability to respond to bath-applied ATP and the cells exhibited wave-like [Ca2+]i increases similar to those in intact cells. Conclusion: Wave-like [Ca2+]i responses in isolated Müller cells are not mediated by an internally propagated signal but rather the endfoot is capable of responding to purinergic agonists independent of the rest of the cell. These data suggest that the endfoot responses to purinergic agonists are inherently delayed with respect to distal/somatic responses. The mechanism for this delay is not yet clear, but these data indicate that the endfeet of Müller cells could respond to ATP released by amacrine cells in the inner retina.

Keywords: 479 Muller cells • 334 calcium • 490 neurotransmitters/neurotransmitter systems 

This PDF is available to Subscribers Only

Sign in or purchase a subscription to access this content. ×

You must be signed into an individual account to use this feature.