title: Properties of heterologously expressed hTRP3 channels in bovine pulmonary artery endothelial cells.
abstract: 1. We combined patch clamp and fura-2 fluorescence methods to characterize human TRP3 (hTRP3) channels heterologously expressed in cultured bovine pulmonary artery endothelial (CPAE) cells, which do not express the bovine trp3 isoform (btrp3) but express btrp1 and btrp4. 2. ATP, bradykinin and intracellular InsP3 activated a non-selective cation current (IhTRP3) in htrp3-transfected CPAE cells but not in non-transfected wild-type cells. During agonist stimulation, the sustained rise in [Ca2+]i was significantly higher in htrp3-transfected cells than in control CPAE cells. 3. The permeability for monovalent cations was PNa > PCs approximately PK >> PNMDG and the ratio PCa/PNa was 1.62 +/- 0.27 (n = 11). Removal of extracellular Ca2+ enhanced the amplitude of the agonist-activated IhTRP3 as well as that of the basal current The trivalent cations La3+ and Gd3+ were potent blockers of IhTRP3 (the IC50 for La3+ was 24.4 +/- 0.7 microM). 4. The single-channel conductance of the channels activated by ATP, assessed by noise analysis, was 23 pS. 5. Thapsigargin and 2,5-di-tert-butyl-1, 4-benzohydroquinone (BHQ), inhibitors of the organellar Ca2+-ATPase, failed to activate IhTRP3. U-73122, a phospholipase C blocker, inhibited IhTRP3 that had been activated by ATP and bradykinin. Thimerosal, an InsP3 receptor-sensitizing compound, enhanced IhTRP3, but calmidazolium, a calmodulin antagonist, did not affect IhTRP3. 6. It is concluded that hTRP3 forms non-selective plasmalemmal cation channels that function as a pathway for agonist-induced Ca2+ influx.
authors.affiliation: Laboratorium voor Fysiologie, Campus Gasthuisberg, KU Leuven, B-3000 Leuven, Belgium.
authors.forename: M
authors.initials: M
authors.lastname: Kamouchi
authors.forename: S
authors.initials: S
authors.lastname: Philipp
authors.forename: V
authors.initials: V
authors.lastname: Flockerzi
authors.forename: U
authors.initials: U
authors.lastname: Wissenbach
authors.forename: A
authors.initials: A
authors.lastname: Mamin
authors.forename: L
authors.initials: L
authors.lastname: Raeymaekers
authors.forename: J
authors.initials: J
authors.lastname: Eggermont
authors.forename: G
authors.initials: G
authors.lastname: Droogmans
authors.forename: B
authors.initials: B
authors.lastname: Nilius
mesh_terms: D000255:Adenosine Triphosphate / Q000502:physiology; D000465:Algorithms; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001920:Bradykinin / Q000502:physiology; D015220:Calcium Channels / Q000502:physiology; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors; D002417:Cattle; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005456:Fluorescent Dyes; D016257:Fura-2; D053496:Inositol 1,4,5-Trisphosphate Receptors; D007473:Ion Channels / Q000235:genetics* / Q000378:metabolism*; D008969:Molecular Sequence Data; D010539:Permeability; D011651:Pulmonary Artery / Q000166:cytology / Q000378:metabolism*; D018160:Receptors, Cytoplasmic and Nuclear / Q000502:physiology; D050052:TRPC Cation Channels; D019284:Thapsigargin / Q000494:pharmacology
chemical_list: D015220:Calcium Channels; D004791:Enzyme Inhibitors; D005456:Fluorescent Dyes; C506926:ITPR1 protein, human; D053496:Inositol 1,4,5-Trisphosphate Receptors; D007473:Ion Channels; D018160:Receptors, Cytoplasmic and Nuclear; D050052:TRPC Cation Channels; C104603:TRPC3 cation channel; D019284:Thapsigargin; D000255:Adenosine Triphosphate; D000252:Calcium-Transporting ATPases; D001920:Bradykinin; D016257:Fura-2