title: Characterization and localization of P2 receptors in rat submandibular gland acinar and duct cells.
abstract: [Ca2+]i and the Cl- current were measured in isolated submandibular gland acinar and duct cells to characterize and localize the purinergic receptors expressed in these cells. In both cell types 2'-3'-benzoylbenzoyl (Bz)-ATP and ATP increased [Ca2+]i mainly by activation of Ca2+ influx. UTP had only minimal effect on [Ca2+]i at concentrations between 0.1 and 1 mM. However, a whole cell current recording showed that all nucleotides effectively activated Cl- currents. Inhibition of signal transduction through G proteins by guanyl-5'-beta-thiophosphate revealed that the effect of ATP on Cl- current was mediated in part by activation of a G protein-coupled and in part by a G protein-independent receptor. BzATP activated exclusively the G protein-independent portion, whereas UTP activated only the G protein-dependent portion of the Cl- current. Measurement of [Ca2+]i in the microperfused duct showed that ATP stimulated a [Ca2+]i increase when applied to the luminal or the basolateral sides. BzATP increased [Ca2+]i only when applied to the luminal side, whereas UTP at 100 microM increased -Ca2+-i only when applied to the basolateral side. The combined results suggest that duct and possibly acinar cells express P2z receptors in the luminal and P2u receptors in the basolateral membrane.
authors.affiliation: Department of Physiology, University of Texas Southwestern Medical Center, Dallas, Texas 75235, USA.
authors.forename: M G
authors.initials: MG
authors.lastname: Lee
authors.forename: W
authors.initials: W
authors.lastname: Zeng
authors.forename: S
authors.initials: S
authors.lastname: Muallem
mesh_terms: D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism; D018118:Chloride Channels / Q000378:metabolism; D016257:Fura-2 / Q000378:metabolism; D006153:Guanosine Diphosphate / Q000031:analogs & derivatives / Q000378:metabolism; D008274:Magnesium / Q000378:metabolism; D051381:Rats; D018048:Receptors, Purinergic P2 / Q000378:metabolism*; D058486:Receptors, Purinergic P2X7; D058473:Receptors, Purinergic P2Y2; D013363:Submandibular Gland / Q000166:cytology* / Q000378:metabolism; D013873:Thionucleotides / Q000378:metabolism; D014544:Uridine Triphosphate / Q000378:metabolism
chemical_list: D018118:Chloride Channels; C546470:P2rx7 protein, rat; C546387:P2ry2 protein, rat; D018048:Receptors, Purinergic P2; D058486:Receptors, Purinergic P2X7; D058473:Receptors, Purinergic P2Y2; D013873:Thionucleotides; D006153:Guanosine Diphosphate; C033901:3'-O-(4-benzoyl)benzoyladenosine 5'-triphosphate; C023427:guanosine 5'-O-(2-thiodiphosphate); D000255:Adenosine Triphosphate; D008274:Magnesium; D002118:Calcium; D016257:Fura-2; D014544:Uridine Triphosphate