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

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dc.contributor.authorGregory, R.
dc.contributor.authorRychkov, G.
dc.contributor.authorBarritt, G.
dc.date.issued2001
dc.description.abstractThe 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.
dc.description.statementofresponsibilityRoland B. Gregory, Grigori Rychkov and Greg J. Barritt
dc.identifier.citationBiochemical Journal, 2001; 354(2):285-290
dc.identifier.doi10.1042/bj3540285
dc.identifier.issn0264-6021
dc.identifier.issn1470-8728
dc.identifier.orcidRychkov, G. [0000-0002-2788-2977]
dc.identifier.urihttp://hdl.handle.net/2440/11738
dc.language.isoen
dc.publisherPortland Press
dc.rightsCopyright © 2001 The Biochemical Society
dc.source.urihttp://www.biochemj.org/bj/354/bj3540285.htm
dc.subjectGadolinium (Gd³+)
dc.subjectH4-IIE cells
dc.subjectmaitotoxin
dc.subjectpatchclamp recording
dc.subjectrat hepatocytes
dc.titleEvidence 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
dc.typeJournal article
pubs.publication-statusPublished

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