Fluorescent Ca 2+ indicators directly inhibit the Na,K-ATPase and disrupt cellular functions

Sci Signal. 2018 Jan 30;11(515):eaal2039. doi: 10.1126/scisignal.aal2039.

Abstract

Fluorescent Ca2+ indicators have been essential for the analysis of Ca2+ signaling events in various cell types. We showed that chemical Ca2+ indicators, but not a genetically encoded Ca2+ indicator, potently suppressed the activity of Na+- and K+-dependent adenosine triphosphatase (Na,K-ATPase), independently of their Ca2+ chelating activity. Loading of commonly used Ca2+ indicators, including Fluo-4 acetoxymethyl (AM), Rhod-2 AM, and Fura-2 AM, and of the Ca2+ chelator BAPTA AM into cultured mouse or human neurons, astrocytes, cardiomyocytes, or kidney proximal tubule epithelial cells suppressed Na,K-ATPase activity by 30 to 80%. Ca2+ indicators also suppressed the agonist-induced activation of the Na,K-ATPase, altered metabolic status, and caused a dose-dependent loss of cell viability. Loading of Ca2+ indicators into mice, which is carried out for two-photon imaging, markedly altered brain extracellular concentrations of K+ and ATP. These results suggest that a critical review of data obtained with chemical Ca2+ indicators may be necessary.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adenosine Triphosphate / metabolism
  • Aniline Compounds / pharmacology
  • Animals
  • Astrocytes / drug effects
  • Astrocytes / enzymology
  • Astrocytes / metabolism*
  • Cells, Cultured
  • Enzyme Inhibitors / pharmacology*
  • Fluorescent Dyes / pharmacology*
  • Fura-2 / pharmacology
  • Heterocyclic Compounds, 3-Ring / pharmacology
  • Humans
  • Kidney Tubules, Proximal / drug effects
  • Kidney Tubules, Proximal / enzymology
  • Kidney Tubules, Proximal / metabolism*
  • Mice
  • Mice, Inbred C57BL
  • Myocytes, Cardiac / drug effects
  • Myocytes, Cardiac / enzymology
  • Myocytes, Cardiac / metabolism*
  • Neurons / drug effects
  • Neurons / enzymology
  • Neurons / metabolism*
  • Potassium / metabolism
  • Sodium-Potassium-Exchanging ATPase / antagonists & inhibitors*
  • Xanthenes / pharmacology

Substances

  • Aniline Compounds
  • Enzyme Inhibitors
  • Fluo 4
  • Fluorescent Dyes
  • Heterocyclic Compounds, 3-Ring
  • Xanthenes
  • rhod-2
  • Adenosine Triphosphate
  • Sodium-Potassium-Exchanging ATPase
  • Potassium
  • Fura-2