Cyclosporine stimulates Na+-K+-Cl- cotransport activity in cultured mouse medullary thick ascending limb cells

Kidney Int. 2000 Oct;58(4):1652-63. doi: 10.1046/j.1523-1755.2000.00326.x.


Background: Cyclosporine (CsA) has been shown to alter the activity of plasma membrane transporters in kidney epithelial cells. In this study, we have investigated the effects of CsA on Na+,K+-ATPase and Na+-K+-Cl- cotransport activities in cultured cells derived from microdissected mouse medullary thick ascending limb (mTAL) cells.

Methods: Experiments were carried out on subcultured confluent mouse TAL cells. Reverse transcription-polymerase chain reaction experiments showed that they expressed the mNKCC2 electroneutral Na+-K+-Cl- cotransporter and ROM-K1 and ROMK2 potassium channel mRNA. Western blotting also revealed the presence of the 40 kD ROMK protein using an anti-ROMK antibody. The effect of CsA (100 ng/mL) on ion transport was assessed by measuring the influx and efflux of rubidium (86Rb+) and 36Cl-, used as tracers of K+ and Cl- movements, on cells grown on Petri dishes or permeable filters.

Results: CsA inhibited by 38% the ouabain-sensitive component of 86Rb+ influx mediated by the Na+,K+-ATPase pumps. CsA also increased by 38% the ouabain-resistant furosemide-sensitive component (Or-Fs) of 86Rb+ influx, reflecting the Na+-K+-Cl- cotransport activity and stimulated the basolateral efflux of 36Cl- from mTAL cells grown on filters. The CsA-stimulated basal efflux of Cl- was prevented by the basal addition of the Cl- channel blocker 5-nitro-2-(3-phenylpropylamino) benzoate (NPPB, 10-4 mol/L). Apical addition of the K+ channel blocking agent Ba2+ (10-4 mol/L) partially prevented the CsA-stimulated basal efflux of Cl-. Adding Ba2+ to the luminal side of cells grown on Petri dishes also prevented the rise in apical 86Rb+ efflux and the increased Or-Fs component of 86Rb+ influx caused by CsA.

Conclusion: These results indicated that CsA may stimulate the Na+-K+-Cl- cotransport activity and also suggested that this immunosuppressive agent may interfere in the recycling of apical K+ in this model of cultured mouse TAL cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Barium / pharmacology
  • Biological Transport / drug effects
  • Biological Transport / physiology
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism*
  • Cells, Cultured
  • Chlorides / metabolism
  • Cyclosporine / pharmacology*
  • Epithelial Cells / cytology
  • Epithelial Cells / drug effects
  • Epithelial Cells / metabolism
  • Gene Expression / physiology
  • Graft Rejection / drug therapy
  • Graft Rejection / metabolism
  • Immunosuppressive Agents / pharmacology*
  • Kidney Medulla / cytology
  • Kidney Medulla / metabolism*
  • Kidney Transplantation / physiology
  • Loop of Henle / cytology
  • Loop of Henle / metabolism*
  • Mice
  • Potassium / metabolism
  • Potassium Channels / genetics
  • Potassium Channels / metabolism
  • Potassium Channels, Inwardly Rectifying*
  • Rubidium Radioisotopes / pharmacokinetics
  • Sodium-Potassium-Chloride Symporters
  • Sodium-Potassium-Exchanging ATPase / metabolism


  • Carrier Proteins
  • Chlorides
  • Immunosuppressive Agents
  • Kcnj1 protein, mouse
  • Potassium Channels
  • Potassium Channels, Inwardly Rectifying
  • Rubidium Radioisotopes
  • Sodium-Potassium-Chloride Symporters
  • Barium
  • Cyclosporine
  • Sodium-Potassium-Exchanging ATPase
  • Potassium