title: Endogenous and exogenous citrate transport and release in prostatic preparations: semi-polarized two-dimensional cultures of human PNT2-C2 cells and isolated tubules and segments of rat prostate.
abstract: BACKGROUND
  Electrophysiological characterization of normal human prostate epithelial cells showed exogenous trivalent citrate transport (release) to be K(+)-dependent.
  
  
  METHODS
  (1) Ussing chamber recordings of short circuit current (SCC) were used to study citrate transport in the same (PNT2-C2) cell line grown on micro-pore filters as a monolayer. (2) Release of endogenous citrate from confluent cultures and tubules and segments of rat prostate was measured using a fluorescence technique. (3) Enzyme-spectrophotometry was employed to detect citrate release from segments of rat prostate.
  
  
  RESULTS
  Citrate transport across the PNT2-C2 monolayer was asymmetrical, consistent with release into the lumen-side. Fluorescence and/or enzyme-spectrophotometric measurements showed that time-dependent citrate release (endogeneous and preabsorbed) occurred from rat prostate (tubules and segments), but not kidney or lung. The release was dependent on extracellular K(+) but not Na(+).
  
  
  CONCLUSIONS
  Citrate release from prostatic cells and tissues (rat and human) was K(+)-dependent, consistent with the previous electrophysiological data.
authors.affiliation: Department of Biological Sciences, Neuroscience Solutions to Cancer Research Group, Imperial College London, London SW7 2AZ, United Kingdom. m.mycielska@imperial.ac.uk
authors.forename: Maria E
authors.initials: ME
authors.lastname: Mycielska
authors.forename: Monika
authors.initials: M
authors.lastname: Krasowska
authors.forename: Zbigniew
authors.initials: Z
authors.lastname: Grzywna
authors.forename: Mustafa B A
authors.initials: MB
authors.lastname: Djamgoz
mesh_terms: D000818:Animals; D001224:Aspartic Acid / Q000494:pharmacology; D001692:Biological Transport; D016764:Cell Polarity; D002478:Cells, Cultured; D019343:Citric Acid / Q000378:metabolism*; D006801:Humans; D008297:Male; D018408:Patch-Clamp Techniques; D011188:Potassium / Q000494:pharmacology; D011467:Prostate / Q000378:metabolism*; D051381:Rats
chemical_list: D019343:Citric Acid; D001224:Aspartic Acid; D011188:Potassium