Evidence that 2-aminoethyl diphenylborate is a novel inhibitor of store-operated Ca2+ channels in liver cells, and acts through a mechanism which does not involve inositol trisphosphate receptors

R. B. Gregory, G. Rychkov, G. J. Barritt

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The compound 2-aminoethyl diphenylborate (2-APB), an inhibitor of Ins(1,4,5)P3 receptor action in some cell types, has been used to assess the role of Ins(1,4,5)P3 receptors in the activation of store-operated Ca2+ channels (SOCs) [Ma. Patterson, van Rossum, Birnbaumer, Mikoshiba and Gill (2000) Science 287. 1647 1651]. In freshly-isolated rat hepatocytes, 2-APB inhibited thapsigargin- and vasopressin-stimulated Ca2+ inflow (measured using fura-2) with no detectable effect on the release of Ca2+ from intracellular stores. The concentration of 2-APB which gave half-maximal inhibition of Ca2+ inflow was approx. 10μM. 2-APB also inhibited Ca2+inflow initiated by a low concentration of adenophostin A but had no effect on maitotoxin-stimulated Ca2+ inflow through non-selective cation channels. The onset of the inhibitory effect of 2-APB on thapsigargin-stimulated Ca2+ inflow was rapid. When 2-APB was added to rat hepatocytes in the presence of extracellular Ca2+ after a vasopressin-induced plateau in the cytoplasmic free Ca2+ concentration ([Ca2+]cyt) had been established, the kinetics of the decrease in [Ca2+]cyt were identical with those induced by the addition of 50μM Gd3+ (gadolinium). 2-APB did not inhibit the release of Ca2+ from intracellular stores induced by the addition of Ins(1,4,5)P3 to permeabilized hepatocytes. In the H4-IIE rat hepatoma cell line. 2-APB inhibited thapsigargin-stimulated Ca2+ inflow (measured using fura-2) and, in whole-cell patch-clamp experiments, the Ins(1,4,5)P3-induced inward current carried by Ca2+. It was concluded that, in liver cells, 2-APB inhibited SOCs through a mechanism which involved the binding of 2-APB to either the channel protein or an associated regulatory protein. 2-APB appeared to be a novel inhibitor of SOCs in liver cells with a mechanism of action which, in this cell type, is unlikely to involve an interaction of 2-APB with Ins(1,4,5)P3 receptors. The need for caution in the use of 2-APB as a probe for the involvement of Ins(1,4,5)P3 receptors in the activation of SOCs in other cell types is briefly discussed.

Original languageEnglish
Pages (from-to)285-290
Number of pages6
JournalBiochemical Journal
Issue number2
Publication statusPublished or Issued - 1 Mar 2001


  • Gadolinium (Gd)
  • H4-IIE cells
  • Maitotoxin
  • Patch-clamp recording
  • Rat hepatocytes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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