Imaging of intracellular calcium stores in single permeabilized lens cells

Am J Physiol. 1999 Feb;276(2):C426-34. doi: 10.1152/ajpcell.1999.276.2.C426.


Intracellular Ca2+ stores in permeabilized sheep lens cells were imaged with mag-fura 2 to characterize their distribution and sensitivity to Ca2+-releasing agents. Inositol 1,4,5-trisphosphate (IP3) or cyclic ADP-ribose (cADPR) released Ca2+ from intracellular Ca2+ stores that were maintained by an ATP-dependent Ca2+ pump. The IP3 antagonist heparin inhibited IP3- but not cADPR-mediated Ca2+ release, whereas the cADPR antagonist 8-amino-cADPR inhibited cADPR- but not IP3-mediated Ca2+ release, indicating that IP3 and cADPR were operating through separate mechanisms. A Ca2+ store sensitive to IP3, cADPR, and thapsigargin appeared to be distributed throughout all intracellular regions. In some cells a Ca2+ store insensitive to IP3, cADPR, thapsigargin, and 2,4-dinitrophenol, but not ionomycin, was present in a juxtanuclear region. We conclude that lens cells contain intracellular Ca2+ stores that are sensitive to IP3, cADPR, and thapsigargin, as well as a Ca2+ store that appears insensitive to all these agents.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adenosine Diphosphate Ribose / analogs & derivatives
  • Adenosine Diphosphate Ribose / pharmacology
  • Animals
  • Calcium / metabolism*
  • Cell Membrane Permeability / physiology
  • Cells, Cultured
  • Cyclic ADP-Ribose
  • Drug Resistance
  • Fluorescent Dyes
  • Fura-2 / analogs & derivatives
  • Inositol 1,4,5-Trisphosphate / pharmacology
  • Intracellular Membranes / drug effects
  • Intracellular Membranes / metabolism*
  • Lens, Crystalline / cytology
  • Lens, Crystalline / drug effects
  • Lens, Crystalline / metabolism*
  • Microscopy, Fluorescence
  • Osmolar Concentration
  • Sheep
  • Substrate Specificity
  • Thapsigargin / pharmacology
  • Tissue Distribution


  • Fluorescent Dyes
  • Cyclic ADP-Ribose
  • Mag-Fura-2-acetoxymethyl ester
  • Adenosine Diphosphate Ribose
  • Thapsigargin
  • Inositol 1,4,5-Trisphosphate
  • Calcium
  • Fura-2