title: Buffer-dependent regulation of aquaporin-1 expression and function in human peritoneal mesothelial cells.
abstract: BACKGROUND
  Biocompatible peritoneal dialysis fluids (PDF) are buffered with lactate and/or bicarbonate. We hypothesized that the reduced toxicity of the biocompatible solutions might unmask specific effects of the buffer type on mesothelial cell functions.
  
  
  METHODS
  Human peritoneal mesothelial cells (HPMC) were incubated with bicarbonate (B-)PDF or lactate-buffered (L-)PDF followed by messenger RNA (mRNA) and protein analysis. Gene silencing was achieved using small interfering RNA (siRNA), functional studies using Transwell culture systems, and monolayer wound-healing assays.
  
  
  RESULTS
  Incubation with B-PDF increased HPMC migration in the Transwell and monolayer wound-healing assay to 245 ± 99 and 137 ± 11% compared with L-PDF. Gene silencing showed this effect to be entirely dependent on the expression of aquaporin-1 (AQP-1) and independent of AQP-3. Exposure of HPMC to B-PDF increased AQP-1 mRNA and protein abundance to 209  ± 80 and 197  ±  60% of medium control; the effect was pH dependent. L-PDF reduced AQP-1 mRNA. Addition of bicarbonate to L-PDF increased AQP-1 abundance by threefold; mRNA half-life remained unchanged. Immunocytochemistry confirmed opposite changes of AQP-1 cell-membrane abundance with B-PDF and L-PDF.
  
  
  CONCLUSIONS
  Peritoneal mesothelial AQP-1 abundance and migration capacity is regulated by pH and buffer agents used in PD solutions. In vivo studies are required to delineate the impact with respect to long-term peritoneal membrane integrity and function.
authors.affiliation: Division of Pediatric Nephrology, Center for Pediatric and Adolescent Medicine, University of Heidelberg, Heidelberg, Germany.
authors.forename: Yihui
authors.initials: Y
authors.lastname: Zhai
authors.forename: Jacek
authors.initials: J
authors.lastname: Bloch
authors.forename: Meike
authors.initials: M
authors.lastname: Hömme
authors.forename: Julia
authors.initials: J
authors.lastname: Schaefer
authors.forename: Thilo
authors.initials: T
authors.lastname: Hackert
authors.forename: Bärbel
authors.initials: B
authors.lastname: Philippin
authors.forename: Vedat
authors.initials: V
authors.lastname: Schwenger
authors.forename: Franz
authors.initials: F
authors.lastname: Schaefer
authors.forename: Claus P
authors.initials: CP
authors.lastname: Schmitt
mesh_terms: D051398:Aquaporin 1 / Q000096:biosynthesis*; D001639:Bicarbonates / Q000494:pharmacology; D015153:Blotting, Western; D002021:Buffers; D002465:Cell Movement / Q000187:drug effects; D002478:Cells, Cultured; D004847:Epithelial Cells / Q000187:drug effects* / Q000378:metabolism; D004848:Epithelium / Q000187:drug effects / Q000378:metabolism; D015312:Hemodialysis Solutions / Q000494:pharmacology*; D006801:Humans; D019344:Lactic Acid / Q000494:pharmacology; D010530:Peritoneal Dialysis / Q000009:adverse effects*; D010537:Peritoneum / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: C496020:AQP1 protein, human; D001639:Bicarbonates; D002021:Buffers; D015312:Hemodialysis Solutions; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D051398:Aquaporin 1; D019344:Lactic Acid