Spatial buffering of light-evoked potassium increases by retinal Müller (glial) cells

Chester J. Karwoski, Hong Kai Lu, Eric A. Newman

Research output: Contribution to journalArticle

162 Scopus citations

Abstract

Activity-dependent variations in extracellular potassium concentration in the central nervous system may be regulated, in part, by potassium spatial buffering currents in glial cells. The role of spatial buffering in the retina was assessed by measuring light-evoked potassium changes in amphibian eyecups. The amplitude of potassium increases in the vitreous humor was reduced to ∼10 percent by 50 micromolar barium, while potassium increases in the inner plexiform layer were largely unchanged. The decrease in the vitreal potassium response was accurately simulated with a numerical model of potassium current flow through Müller cells, the principal glial cells of the retina. Barium also substantially increased the input resistance of Müller cells and blocked the Müller cell-generated M-wave, indicating that barium blocks the potassium channels of Müller cells. Thus, after a light-evoked potassium increase within the retina, there is a substantial transfer of potassium from the retina to the vitreous humor by potassium current flow through Müller cells.

Original languageEnglish (US)
Pages (from-to)578-580
Number of pages3
JournalScience
Volume244
Issue number4904
DOIs
StatePublished - Jan 1 1989

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