title: [P2X4 or P2X7: which of these two receptors is the best target to promote salivation?].
abstract: P2X purinergic receptors are receptors which, after ATP binding, form a channel permeant to monovalent and divalent cations. Acinar and ductal cells from salivary glands express P2X4 and P2X7 receptors. The P2X4 receptor has a high affinity for ATP, rapidly desensitizes and is mostly located on the basal membrane of acinar cells. The P2X7 receptor has a very low affinity for ATP. After a sustained activation, the permeability of the channel formed by this receptor increases eventually leading to the death of the cell. This receptor is located mostly on the apical membrane of acinar and ductal cells. It is suggested that the sequential activation of the two receptors contributes to the secretory response to ATP. A low concentration of ATP released by nerve endings transiently activates the P2X4 receptors and promotes the release of secretory granules containing ATP. The local increase of the concentration of the nucleotide at the vicinity of P2X7 receptors accounts for their activation. This further increases the exocytosis.
authors.affiliation: Laboratoire de chimie biologique et médicale et de microbiologie pharmaceutique, laboratoire de physiologie et de pharmacologie, faculté de pharmacie, université libre de Bruxelles, Bruxelles, Belgique.
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Pochet
authors.forename: Michèle
authors.initials: M
authors.lastname: Seil
authors.forename: Malika
authors.initials: M
authors.lastname: El Ouaaliti
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Dehaye
mesh_terms: D006801:Humans; D058848:Receptors, Purinergic P2X4 / Q000502:physiology*; D058486:Receptors, Purinergic P2X7 / Q000502:physiology*; D012469:Salivary Glands / Q000378:metabolism*; D012472:Salivation / Q000502:physiology*; D015398:Signal Transduction
chemical_list: D058848:Receptors, Purinergic P2X4; D058486:Receptors, Purinergic P2X7