title: 2-Aminoethoxydiphenyl borate (2-APB) antagonises inositol 1,4,5-trisphosphate-induced calcium release, inhibits calcium pumps and has a use-dependent and slowly reversible action on store-operated calcium entry channels.
abstract: The action of 2-aminoethoxydiphenyl borate (2-APB) on Ca(2+) signalling in HeLa cells and cardiac myocytes was investigated. Consistent with other studies, we found that superfusion of cells with 2-APB rapidly inhibited inositol 1,4,5-trisphosphate (InsP(3))-mediated Ca(2+) release and store-operated Ca(2+) entry (SOC). In addition to abrogating hormone-evoked Ca(2+) responses, 2-APB could antagonise Ca(2+) signals evoked by a membrane permeant InsP(3) ester. 2-APB also slowed the recovery of intracellular Ca(2+) signals consistent with an effect on Ca(2+) ATPases. The inhibitory action of 2-APB on InsP(3) receptors (InsP(3)Rs), SOC channels and Ca(2+) pumps persisted for several minutes after washout of the compound. Application of 2-APB to unstimulated cells had no effect on subsequent Ca(2+) responses suggesting that it has a use-dependent action. Mitochondria in cells treated with 2-APB showed a rapid and slowly reversible swelling. 2-APB did not cause the mitochondria to depolarise, but it reduced the extent of mitochondrial calcium uptake. Although 2-APB has been demonstrated not to affect voltage-operated Ca(2+) channels or ryanodine receptors, we found that it gave a concentration-dependent long-lasting inhibition of Ca(2+) signalling in electrically-stimulated cardiac myocytes, where InsP(3)Rs and SOC channels do not play a significant role. Our data suggest that 2-APB has multiple cellular targets, a use-dependent action, is difficult to reverse and may affect Ca(2+) signalling in cell types where InsP(3) and SOC are not active.
authors.affiliation: Laboratory of Molecular Signalling, The Babraham Institute, Babraham, Cambridge CB2 4AT, UK.
authors.forename: Claire M
authors.initials: CM
authors.lastname: Peppiatt
authors.forename: Tony J
authors.initials: TJ
authors.lastname: Collins
authors.forename: Lauren
authors.initials: L
authors.lastname: Mackenzie
authors.forename: Stuart J
authors.initials: SJ
authors.lastname: Conway
authors.forename: Andrew B
authors.initials: AB
authors.lastname: Holmes
authors.forename: Martin D
authors.initials: MD
authors.lastname: Bootman
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Berridge
authors.forename: Jeong T
authors.initials: JT
authors.lastname: Seo
authors.forename: H Llewelyn
authors.initials: HL
authors.lastname: Roderick
mesh_terms: D001896:Boron Compounds / Q000494:pharmacology*; D015220:Calcium Channels / Q000187:drug effects* / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects* / Q000502:physiology; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002463:Cell Membrane Permeability / Q000187:drug effects / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D006367:HeLa Cells; D006801:Humans; D015544:Inositol 1,4,5-Trisphosphate / Q000037:antagonists & inhibitors* / Q000378:metabolism / Q000494:pharmacology; D053496:Inositol 1,4,5-Trisphosphate Receptors; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D032383:Myocytes, Cardiac; D018160:Receptors, Cytoplasmic and Nuclear / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D001896:Boron Compounds; D015220:Calcium Channels; C506926:ITPR1 protein, human; D053496:Inositol 1,4,5-Trisphosphate Receptors; D018160:Receptors, Cytoplasmic and Nuclear; D015544:Inositol 1,4,5-Trisphosphate; C109986:2-aminoethoxydiphenyl borate; D000252:Calcium-Transporting ATPases