title: Involvement of P-glycoprotein in the transport of saquinavir and indinavir in rat brain microvessel endothelial and microglia cell lines.
abstract: OBJECTIVE
  Membrane-bound efflux transporters, such as P-glycoprotein (P-gp), may limit the brain entry and distribution of HIV-1 protease inhibitors and be in part responsible for HIV-1-associated dementia treatment failure. The purpose of this study was to characterize the transport properties of saquinavir and indinavir in a brain microvessel endothelial cell line and in microglia, the immune cells of the brain and primary HIV-1 cellular target.
  
  
  METHODS
  Biochemical and transport studies were performed in an immortalized rat brain endothelial cell line (RBE4), a rat microglia cell line (MLS-9), and a P-gp overexpressing Chinese hamster ovary cell line (CHRC5).
  
  
  RESULTS
  Western blot analysis using the P-gp monoclonal antibody C219 detected a single band at approximately 170 to 180 kDa (a size previously reported for P-gp) in all cell lines. Cellular accumulation of [14C]saquinavir and [3H]indinavir by RBE4, MLS-9, and CHRC5 monolayers was significantly enhanced in the presence of P-gp inhibitors, HIV-1 protease inhibitors, the ATPase inhibitor sodium azide, and the ATP depleting agent 2',4'-dinitrophenol respectively. [14C]Saquinavir and [3H]indinavir efflux from both cell systems was rapid and significantly reduced in the presence of PSC833.
  
  
  CONCLUSIONS
  These results provide evidence for P-gp mediated transport of saquinavir and indinavir in RBE4 and MLS-9 and suggest that this transporter can restrict, at least in part, the permeation of HIV-1 protease inhibitors at both the brain barrier site and in brain parenchyma.
authors.affiliation: Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Patrick T
authors.initials: PT
authors.lastname: Ronaldson
authors.forename: Gloria
authors.initials: G
authors.lastname: Lee
authors.forename: Shannon
authors.initials: S
authors.lastname: Dallas
authors.forename: Reina
authors.initials: R
authors.lastname: Bendayan
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000037:antagonists & inhibitors / Q000502:physiology*; D000818:Animals; D019380:Anti-HIV Agents / Q000493:pharmacokinetics*; D000963:Antimetabolites / Q000494:pharmacology; D001693:Biological Transport, Active; D015153:Blotting, Western; D016466:CHO Cells; D002460:Cell Line; D006224:Cricetinae; D042783:Endothelial Cells / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D017320:HIV Protease Inhibitors / Q000493:pharmacokinetics*; D019469:Indinavir / Q000493:pharmacokinetics*; D017628:Microglia / Q000378:metabolism*; D011480:Protease Inhibitors / Q000494:pharmacology; D051381:Rats; D019258:Saquinavir / Q000493:pharmacokinetics*
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D019380:Anti-HIV Agents; D000963:Antimetabolites; D017320:HIV Protease Inhibitors; D011480:Protease Inhibitors; D019469:Indinavir; D019258:Saquinavir