title: An intact kidney slice model to investigate vasa recta properties and function in situ.
abstract: BACKGROUND
  Medullary blood flow is via vasa recta capillaries, which possess contractile pericytes. In vitro studies using isolated descending vasa recta show that pericytes can constrict/dilate descending vasa recta when vasoactive substances are present. We describe a live kidney slice model in which pericyte-mediated vasa recta constriction/dilation can be visualized in situ.
  
  
  METHODS
  Confocal microscopy was used to image calcein, propidium iodide and Hoechst labelling in 'live' kidney slices, to determine tubular and vascular cell viability and morphology. DIC video-imaging of live kidney slices was employed to investigate pericyte-mediated real-time changes in vasa recta diameter.
  
  
  RESULTS
  Pericytes were identified on vasa recta and their morphology and density were characterized in the medulla. Pericyte-mediated changes in vasa recta diameter (10-30%) were evoked in response to bath application of vasoactive agents (norepinephrine, endothelin-1, angiotensin-II and prostaglandin E(2)) or by manipulating endogenous vasoactive signalling pathways (using tyramine, L-NAME, a cyclo-oxygenase (COX-1) inhibitor indomethacin, and ATP release).
  
  
  CONCLUSIONS
  The live kidney slice model is a valid complementary technique for investigating vasa recta function in situ and the role of pericytes as regulators of vasa recta diameter. This technique may also be useful in exploring the role of tubulovascular crosstalk in regulation of medullary blood flow.
authors: Medway School of Pharmacy, The Universities of Kent and Greenwich at Medway, Chatham, UK.
authors: C
authors: C
authors: Crawford
authors: T
authors: T
authors: Kennedy-Lydon
authors: C
authors: C
authors: Sprott
authors: T
authors: T
authors: Desai
authors: L
authors: L
authors: Sawbridge
authors: J
authors: J
authors: Munday
authors: R J
authors: RJ
authors: Unwin
authors: S S P
authors: SS
authors: Wildman
authors: C M
authors: CM
authors: Peppiatt-Wildman
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000804:Angiotensin II / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D000941:Antigens / Q000378:metabolism; D002196:Capillaries / Q000166:cytology / Q000502:physiology*; D002470:Cell Survival / Q000502:physiology; D019332:Endothelin-1 / Q000378:metabolism / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D007213:Indomethacin / Q000494:pharmacology; D007679:Kidney Medulla / Q000098:blood supply* / Q000294:innervation / Q000378:metabolism; D008297:Male; D018613:Microscopy, Confocal; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009638:Norepinephrine / Q000378:metabolism / Q000494:pharmacology; D020286:Pericytes / Q000166:cytology / Q000502:physiology*; D011509:Proteoglycans / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects; D013564:Sympathetic Nervous System / Q000502:physiology; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology*; D014662:Vasoconstrictor Agents / Q000378:metabolism / Q000494:pharmacology; D000099216:Chondroitin Sulfate Proteoglycan 4
chemical_list: D000255:Adenosine Triphosphate; D000804:Angiotensin II; D000941:Antigens; D019332:Endothelin-1; D004791:Enzyme Inhibitors; D007213:Indomethacin; D019331:NG-Nitroarginine Methyl Ester; D009638:Norepinephrine; D011509:Proteoglycans; D014662:Vasoconstrictor Agents; D000099216:Chondroitin Sulfate Proteoglycan 4