title: The glomerular filtration barrier function:  new concepts.
abstract: OBJECTIVE
  Each day, the human kidneys filter about 140 l of primary urine from plasma. Although this ultrafiltrate is virtually free of plasma protein, the glomerular filter never clogs under physiological conditions. Upto today it is still not entirely resolved as to how the kidney accomplishes this extraordinary task. Most of the proposed models for glomerular filtration have not considered electrical effects.
  
  
  RESULTS
  In micropuncture studies, we have directly measured an electrical field across the glomerular filtration barrier. This potential difference is most likely generated by forced passage of the ionic solution of the plasma across the charged glomerular filter ('electrokinetic potential'). As all plasma proteins are negatively charged, the electrical field across the glomerular filtration barrier is predicted to drive plasma proteins from the filter toward the capillary lumen by electrophoresis.
  
  
  CONCLUSIONS
  In this review, we examine our novel model for glomerular filtration in more detail. We outline the physical mechanisms by which electrokinetic effects (streaming potentials) are generated. We investigate the potential impact of the electrical field on the passage of albumin across the glomerular filtration barrier. We review the mathematical heteroporous model including electrical effects and analyse a selection of experimental studies for indications that electrical effects influence glomerular permeability significantly.
authors.affiliation: University Hospital of RWTH Aachen University, Institute for Numerical Mathematics, RWTH Aachen University, Aachen, Germany.
authors.forename: Ralf
authors.initials: R
authors.lastname: Hausmann
authors.forename: Martin
authors.initials: M
authors.lastname: Grepl
authors.forename: Volker
authors.initials: V
authors.lastname: Knecht
authors.forename: Marcus J
authors.initials: MJ
authors.lastname: Moeller
mesh_terms: D000818:Animals; D004553:Electric Conductivity; D004586:Electrophoresis; D004705:Endocytosis; D060730:Glomerular Filtration Barrier / Q000378:metabolism*; D005919:Glomerular Filtration Rate; D006801:Humans; D017136:Ion Transport; D008954:Models, Biological; D010539:Permeability; D012709:Serum Albumin / Q000378:metabolism*
chemical_list: D012709:Serum Albumin