Fractional contribution of calcium to the cation current through glutamate receptor channels

R. Schneggenburger, Z. Zhou, A. Konnerth, E. Neher

Research output: Contribution to journalArticlepeer-review

249 Scopus citations

Abstract

The Ca2+ fraction of the ion current flowing through glutamatergic NMDA and AMPA/kainate receptor channels was determined in forebrain neurons of the medial septum. The neurons were overloaded with the Ca2+ indicator dye fura-2 (1 mM) via the recording patch pipettes. This approach allowed the direct determination of the Ca2+ influx from changes in the Ca2+-sensitive fura-2 fluorescence. We found that, at negative membrane potentials and at an extracellular free Ca2+ concentration of 1.6 mM, the Ca2+ fraction of the current through the NMDA receptor channels is only 6.8%, about 2-fold lower than previously estimated from reversal potential measurements. Interestingly, a quite high fractional Ca2+ current of 1.4% was determined for the linearly conducting AMPA/kainate receptor channels found in these neurons.

Original languageEnglish
Pages (from-to)133-143
Number of pages11
JournalNeuron
Volume11
Issue number1
DOIs
StatePublished - Jul 1993
Externally publishedYes

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