Effects of phorbol ester on intracellular Ca2+ and membrane currents in cultured human microglia

Andrew S.J. Yoo, James G. McLarnon, Rending L. Xu, Yong Beom Lee, Charles Krieger, Seung U. Kim

Research output: Contribution to journalArticle

9 Scopus citations


The effects of protein kinase C (PKC) activation by phorbol ester on intracellular Ca2+ concentration ([Ca2+](i)) and membrane currents in human microglia grown in culture were investigated. Treatment of microglia with phorbol myristate acetate (PMA) resulted in a large increase in [Ca2+](i) in cells loaded with fura-2. The increased levels of [Ca2+](i) were not altered following removal of the phorbol ester. In Ca2+-free medium, application of PMA did not increase [Ca2+](i). In addition, PMA application in standard Ca2+-solution containing lanthanum (1.8 mM) had no effect on the microglial response to PMA, suggesting that the phorbol ester actions were due to transmembrane influx of Ca2+ but not through voltage-gated Ca2+ channels. Whole-cell patch clamp measurements demonstrated that PMA potentiated an outward K+ current and inhibited an inward rectifier K+ current. This study is the first demonstration that PKC activation by phorbol ester leads to increased intracellular [Ca2+] and changes in membrane currents in human microglia.

Original languageEnglish
Pages (from-to)37-40
Number of pages4
JournalNeuroscience Letters
Issue number1
StatePublished - Oct 25 1996
Externally publishedYes


  • Fura-2
  • Human microglia
  • Intracellular calcium
  • K current
  • Patch clamp
  • Phorbol ester

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