Calcium extrusion from mammalian photoreceptor terminals

Catherine Morgans, Oussama El Far, Amy Berntson, Heinz Wässle, William Taylor

Research output: Contribution to journalArticle

98 Citations (Scopus)

Abstract

Ribbon synapses of vertebrate photoreceptors constantly release glutamate in darkness. Transmitter release is maintained by a steady influx of calcium through voltage-dependent calcium channels, implying the presence of a mechanism that is able to extrude calcium at an equal rate. The two predominant mechanisms of intracellular calcium extrusion are the plasma membrane calcium ATPase (PMCA) and the Na+/Ca2+-exchanger. Immunohistochemical staining of retina sections revealed strong immunoreactivity for the PMCA in rod and cone terminals, whereas staining for the Na+/Ca2+-exchanger was very weak. The PMCA was localized to the plasma membrane along the sides of the photoreceptor terminals and was excluded from the base of the terminals where the active zones are located. The amplitude of a calcium-activated chloride current was used to monitor the intracellular calcium concentration. An upper limit for the time required to remove intracellular free calcium is obtained from two time constants measured for the calcium-activated chloride current tail currents: one of 50 msec and a second of 190 msec. Calcium extrusion was inhibited in the absence of intracellular ATP or in the presence of the PMCA inhibitor orthovanadate, but was unaffected by replacement of external Na+ with Li+. The data indicate that the PMCA, rather than the Na+/Ca2+-exchanger, is the predominant mechanism for calcium extrusion from photoreceptor synaptic terminals.

Original languageEnglish (US)
Pages (from-to)2467-2474
Number of pages8
JournalJournal of Neuroscience
Volume18
Issue number7
StatePublished - Apr 1 1998
Externally publishedYes

Fingerprint

Plasma Membrane Calcium-Transporting ATPases
Calcium
Calcium Chloride
Vertebrate Photoreceptor Cells
Staining and Labeling
Vanadates
Darkness
Presynaptic Terminals
Calcium Channels
Synapses
Retina
Glutamic Acid
Adenosine Triphosphate
Cell Membrane

Keywords

  • Ca-ATPase
  • Calcium extrusion
  • Na/Ca exchanger
  • Photoreceptors
  • Retina

ASJC Scopus subject areas

  • Neuroscience(all)

Cite this

Morgans, C., El Far, O., Berntson, A., Wässle, H., & Taylor, W. (1998). Calcium extrusion from mammalian photoreceptor terminals. Journal of Neuroscience, 18(7), 2467-2474.

Calcium extrusion from mammalian photoreceptor terminals. / Morgans, Catherine; El Far, Oussama; Berntson, Amy; Wässle, Heinz; Taylor, William.

In: Journal of Neuroscience, Vol. 18, No. 7, 01.04.1998, p. 2467-2474.

Research output: Contribution to journalArticle

Morgans, C, El Far, O, Berntson, A, Wässle, H & Taylor, W 1998, 'Calcium extrusion from mammalian photoreceptor terminals', Journal of Neuroscience, vol. 18, no. 7, pp. 2467-2474.
Morgans C, El Far O, Berntson A, Wässle H, Taylor W. Calcium extrusion from mammalian photoreceptor terminals. Journal of Neuroscience. 1998 Apr 1;18(7):2467-2474.
Morgans, Catherine ; El Far, Oussama ; Berntson, Amy ; Wässle, Heinz ; Taylor, William. / Calcium extrusion from mammalian photoreceptor terminals. In: Journal of Neuroscience. 1998 ; Vol. 18, No. 7. pp. 2467-2474.
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