title: Age-dependent changes in the regulation mechanisms for intracellular calcium ions in ganglion cells of the mouse retina.
abstract: The purpose of this study was to investigate the role of intracellular calcium buffering in retinal ganglion cells. We performed a quantitative analysis of calcium homeostasis in ganglion cells of early postnatal and adult mice by simultaneous patch-clamp recordings in sliced tissue and microfluorometric calcium measurements with Fura-2. Endogenous calcium homeostasis was quantified by using the 'added buffer' approach which uses amplitudes and decay time constants of calcium transients to give a standard for intracellular calcium buffering. The recovery phase of depolarization-induced calcium transients was well approximated by a mono-exponential function with a decay time constant that showed a linear dependence on dye concentration. Endogenous calcium binding ratios were found to be 575 (n = 18 cells) in early postnatal and 121 (n = 18 cells) in adult retinal ganglion cells. With respect to ganglion cell degeneration at early postnatal stages, our measurements suggest that neuroprotection of a majority of developing ganglion cells partially results from a specialized calcium homeostasis based on high buffering capacities. Furthermore, the dramatic decrease of the intracellular calcium buffering capacity during ganglion cell development may enhance their vulnerability to neurodegeneration.
authors.affiliation: Department of Ophthalmology II, Augenklinik Abt. II, Forschungsstelle Experimentelle Ophthalmologie, Röntgenweg 11, 72076 Tübingen, Germany.
authors.forename: Miriam
authors.initials: M
authors.lastname: Mann
authors.forename: Wadood
authors.initials: W
authors.lastname: Haq
authors.forename: Thomas
authors.initials: T
authors.lastname: Zabel
authors.forename: Elke
authors.initials: E
authors.lastname: Guenther
authors.forename: Eberhart
authors.initials: E
authors.lastname: Zrenner
authors.forename: Thomas
authors.initials: T
authors.lastname: Ladewig
mesh_terms: D000375:Aging / Q000502:physiology*; D000465:Algorithms; D000818:Animals; D002021:Buffers; D002118:Calcium / Q000502:physiology*; D020013:Calcium Signaling / Q000502:physiology; D004594:Electrophysiology; D006706:Homeostasis / Q000502:physiology; D066298:In Vitro Techniques; D007700:Kinetics; D051379:Mice; D018408:Patch-Clamp Techniques; D012160:Retina / Q000254:growth & development; D012165:Retinal Ganglion Cells / Q000502:physiology*
chemical_list: D002021:Buffers; D002118:Calcium