Calcium regulation of endothelin-1 synthesis in rat inner medullary collecting duct

Am J Physiol Renal Physiol. 2007 Aug;293(2):F601-6. doi: 10.1152/ajprenal.00085.2007. Epub 2007 Jun 6.


Collecting duct-derived endothelin-1 (ET-1) reduces blood pressure and inhibits Na and water reabsorption. Collecting duct ET-1 production is increased by volume expansion; however, the mechanism by which this occurs is unknown. We hypothesized that intracellular calcium, which is likely to be increased by volume expansion, regulates collecting duct ET-1 synthesis. Rat inner medullary collecting ducts (IMCD) were studied in primary culture. ET-1 release was decreased by 50-70% after chelation of intracellular calcium (BAPTA) or inhibition of CaM (W7) or CaMK (KN-93). These agents reduced ET-1 mRNA to a similar degree. CaM inhibition did not affect ET-1 mRNA stability. Transfection of IMCD with rat ET-1 promoter-luciferase constructs revealed maximal activity within 1.7 kb 5' to the transcription start site; 5, 20, 35, and 90% of this activity were in the 0.08-, 0.37-, 1.0-, and 3.0-kb promoter regions, respectively. W7 markedly inhibited activity of the 3.0-kb but not 0.37- or 1.0-kb promoter regions. In contrast, W7 did not affect ET-1 release by rat aortic endothelial cells. Furthermore, transfected endothelial cells had maximal activity in the 0.37-kb region (as compared with the 1.7- and 3.0-kb regions), whereas W-7 had no effect on the activity of any of these promoter regions. In summary, IMCD ET-1 synthesis is regulated by calcium/CaM/CaMK-dependent pathways. The calcium/CaM-sensitive pathway is active in IMCD, but not endothelial cells. This suggests that IMCD-specific enhancer elements exist within the ET-1 promoter that confer unique calcium responsiveness.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Calcium / physiology*
  • Cells, Cultured
  • Endothelin-1 / biosynthesis*
  • Genes, Reporter / genetics
  • Kidney Medulla / metabolism*
  • Kidney Tubules, Collecting / metabolism*
  • Luciferases / biosynthesis
  • Luciferases / genetics
  • RNA / biosynthesis
  • RNA / genetics
  • RNA, Messenger / biosynthesis
  • RNA, Messenger / genetics
  • Rats
  • Signal Transduction / physiology
  • Transfection


  • Endothelin-1
  • RNA, Messenger
  • RNA
  • Luciferases
  • Calcium