Microglia generate external proton and potassium ion gradients utilizing a member of the H/K ATPase family

Orian Shirihai, Peter Smith, Kassia Hammar, Daniel Dagan

Research output: Contribution to journalArticlepeer-review

30 Scopus citations


An ion selective electrode in self-referencing mode was employed to detect ionic concentration gradients at the vicinity of microglia isolated from newborn rat brains. At 5 mM extracellular potassium concentration, a gradient of -9.43 ± 4.2 μM (n = 48) was recorded dissipating over a distance of 10 μm from the outer surface of the cell membrane. Pharmacological studies indicated that neither the Na+/K+-ATPase nor the inward rectifier potassium channel makes significant contributions to generation of this gradient. The recorded potassium gradient was found to be augmented by increase in extracellular potassium or proton concentrations and could be inhibited by Omeprazole (10 μM) and by the specific H+/K+-ATPase blocker SCH28080 (1 μM). These, along with the coexistence of a gradient of excess of protons, strongly suggest that a K/H ATPase is the major generator of both the potassium and the proton gradients. The Kd of the glial transporter for K ions is an order of magnitude higher (3.7 mM) than that of the epithelial H+/K+-ATPase. This is a first report of an H+/K+ transporter in microglia cells with a Kd in the physiological range of [K+](out). Implications of the H+/K+-ATPase on potassium homeostasis in microglia under high extracellular potassium and low pH, as found at the site of brain injury, are discussed.

Original languageEnglish
Pages (from-to)339-348
Number of pages10
Issue number4
StatePublished - 1 Aug 1998
Externally publishedYes


  • Inward rectifier
  • Ion selective probe
  • Omeprazole
  • SCH28080

ASJC Scopus subject areas

  • Neurology
  • Cellular and Molecular Neuroscience


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