title: Flow regulation of endothelin-1 production in the inner medullary collecting duct.
abstract: Collecting duct-derived endothelin (ET)-1 is an autocrine inhibitor of Na(+) and water reabsorption; its deficiency causes hypertension and water retention. Extracellular fluid volume expansion increases collecting duct ET-1, thereby promoting natriuresis and diuresis; however, how this coupling between volume expansion and collecting duct ET-1 occurs is incompletely understood. One possibility is that volume expansion increases tubular fluid flow. To investigate this, cultured IMCD3 cells were subjected to static or flow conditions. Exposure to a shear stress of 2 dyn/cm(2) for 2 h increased ET-1 mRNA content by ∼2.3-fold. Absence of perfusate Ca(2+), chelation of intracellular Ca(2+), or inhibition of Ca(2+) signaling (calmodulin, Ca(2+)/calmodulin-dependent kinase, calcineurin, PKC, or phospholipase C) prevented the flow response. Evaluation of possible flow-activated Ca(2+) entry pathways revealed no role for transient receptor potential (TRP)C3, TRPC6, and TRPV4; however, cells with TRPP2 (polycystin-2) knockdown had no ET-1 flow response. Flow increased intracellular Ca(2+) was blunted in TRPP2 knockdown cells. Nonspecific blockade of P2 receptors, as well as specific inhibition of P2X7 and P2Y2 receptors, prevented the ET-1 flow response. The ET-1 flow response was not affected by inhibition of either epithelial Na(+) channels or the mitochondrial Na(+)/Ca(2+) exchanger. Taken together, these findings provide evidence that in IMCD3 cells, flow, via polycystin-2 and P2 receptors, engages Ca(2+)-dependent signaling pathways that stimulate ET-1 synthesis.
authors.affiliation: Division of Nephrology, University of Utah Health Sciences Center, Salt Lake City, Utah; Department of Pharmaceutics and Pharmaceutical Chemistry, Salt Lake City, Utah;
authors.forename: Meghana M
authors.initials: MM
authors.lastname: Pandit
authors.affiliation: University of Alabama at Birmingham, Birmingham, Alabama;
authors.forename: Edward W
authors.initials: EW
authors.lastname: Inscho
authors.affiliation: University of Alabama at Birmingham, Birmingham, Alabama;
authors.forename: Shali
authors.initials: S
authors.lastname: Zhang
authors.affiliation: Department of Medical Education, California Northstate University, Elk Grove, California;
authors.forename: Tsugio
authors.initials: T
authors.lastname: Seki
authors.affiliation: Department of Medicine, James J. Peter Veterans Affairs Medical Center, Bronx, New York; Department of Medicine and Pediatrics, Icahn School of Medicine at Mount Sinai, New York, New York; and.
authors.forename: Rajeev
authors.initials: R
authors.lastname: Rohatgi
authors.affiliation: Department of Medicine, James J. Peter Veterans Affairs Medical Center, Bronx, New York; Department of Medicine and Pediatrics, Icahn School of Medicine at Mount Sinai, New York, New York; and.
authors.forename: Luca
authors.initials: L
authors.lastname: Gusella
authors.affiliation: Division of Nephrology, University of Utah Health Sciences Center, Salt Lake City, Utah; Salt Lake Veterans Affairs Medical Center, Salt Lake City, Utah.
authors.forename: Bellamkonda
authors.initials: B
authors.lastname: Kishore
authors.affiliation: Division of Nephrology, University of Utah Health Sciences Center, Salt Lake City, Utah; Department of Pharmaceutics and Pharmaceutical Chemistry, Salt Lake City, Utah; Salt Lake Veterans Affairs Medical Center, Salt Lake City, Utah donald.kohan@hsc.utah.edu.
authors.forename: Donald E
authors.initials: DE
authors.lastname: Kohan
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling; D002460:Cell Line; D004231:Diuresis; D019332:Endothelin-1 / Q000378:metabolism*; D053503:Epithelial Sodium Channels / Q000378:metabolism; D007679:Kidney Medulla / Q000378:metabolism*; D007685:Kidney Tubules, Collecting / Q000378:metabolism*; D008297:Male; D051379:Mice; D009318:Natriuresis; D012333:RNA, Messenger / Q000378:metabolism; D017207:Rats, Sprague-Dawley; D011983:Receptors, Purinergic / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism; D050396:TRPP Cation Channels / Q000378:metabolism*; D050051:Transient Receptor Potential Channels / Q000378:metabolism; D014867:Water / Q000378:metabolism
chemical_list: D002118:Calcium; D019332:Endothelin-1; D053503:Epithelial Sodium Channels; D012333:RNA, Messenger; D011983:Receptors, Purinergic; D012964:Sodium; D050396:TRPP Cation Channels; D050051:Transient Receptor Potential Channels; D014867:Water
keywords: collecting duct; endothelin; flow; purinergic