title: Effects of UTP on Na+, Cl- and K+ transport in primary cultures from human sweat gland coils.
abstract: Extracellular ATP and UTP can increase membrane permeability in the sweat gland, but the intracellular signalling regulating the response to these agonists is poorly understood. Stimulation of Cl- transport by nucleotides has been suggested as a pharmacological therapy to improve Cl- secretion in patients with cystic fibrosis. In the present study, regulation of Na+, Cl- and K+ transport in primary cultures of cells from the secretory coil of human sweat glands was investigated by electron probe X-ray microanalysis. Stimulation with 200 microM UTP for 2 min at room temperature caused a significant increase in intracellular Na but did not affect Cl and K. After 5 min, the Na concentration was still increased, but now also a significant decrease in Cl and K was observed, indicating an increase in Cl- and K+ permeability. The effect of UTP on Cl- secretion was enhanced in Mg2+-deficient buffer, indicating that the response is elicited by the extracellular fully ionized form of UTP (UTP4+), but not by MgUTP2+. The effects of UTP were abolished in Ca2+-deficient buffer supplemented with EGTA. Alloxan, an adenylate cyclase inhibitor, did not inhibit the response to UTP. These results indicate that the membrane Cl- and K+ permeability elicited by UTP in primary coil cell cultures is Ca2+-dependent. The response to UTP did not attenuate at 8 degrees C, suggesting that it could be activated, in part, via ligand-gated ion channels. The effect of UTP was not decreased in the presence of ouabain. Pre-treatment of the cells with pertussis toxin (24 h) had minor effects on Cl- secretion activated by UTP, indicating a role for G proteins in the UTP activation of Cl- secretion.
authors: Department of Medical Cell Biology, University of Uppsala, Sweden.
authors: J
authors: J
authors: Hongpaisan
authors: G M
authors: GM
authors: Roomans
mesh_terms: D037361:Adenylate Cyclase Toxin; D002118:Calcium / Q000494:pharmacology; D002463:Cell Membrane Permeability / Q000187:drug effects; D002478:Cells, Cultured; D002712:Chlorides / Q000378:metabolism*; D003080:Cold Temperature; D000242:Cyclic AMP / Q000494:pharmacology; D004577:Electron Probe Microanalysis; D006801:Humans; D017136:Ion Transport / Q000187:drug effects; D008274:Magnesium / Q000494:pharmacology; D008854:Microscopy, Electron; D010042:Ouabain / Q000494:pharmacology; D037342:Pertussis Toxin; D011188:Potassium / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism*; D013545:Sweat Glands / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D014544:Uridine Triphosphate / Q000494:pharmacology*; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
chemical_list: D037361:Adenylate Cyclase Toxin; D002712:Chlorides; D010566:Virulence Factors, Bordetella; D010042:Ouabain; D012964:Sodium; D000242:Cyclic AMP; D037342:Pertussis Toxin; D008274:Magnesium; D011188:Potassium; D002118:Calcium; D014544:Uridine Triphosphate