title: Ischaemia/reperfusion in rat renal cortex: vesicle leakiness and Na+, K+-ATPase activity in membrane preparations.
abstract: BACKGROUND
  Despite the central role of Na(+), K(+)-ATPase (NKA) in ischaemic renal injury (IRI), cortical NKA activity values during renal ischaemia remain controversial. In this study, we explore why cortical NKA activity shows such behaviour during ischaemia in rats.
  
  
  METHODS
  Ischaemia was induced by unilateral renal artery clamping (40 min, I) followed or not by reperfusion (60 min, IR). NKA alpha- and beta-subunit abundance was analysed by western blot. We studied the NKA detergent sodium dodecyl sulphate (SDS) enzymatic activation in isolated membrane preparations from control and ischaemic kidneys.
  
  
  RESULTS
  NKA activity was diminished in I cortical homogenates (C = 9.3 +/- 1.1, I = 4.7 +/- 1.1* micromol Pi/h mg Prot, n = 4-6, *P < 0.05 versus C). This was rapidly recovered after reperfusion (IR = 9.9 +/- 1.2 micromol Pi/h mg Prot). alpha-subunit levels were increased, while beta-subunit was unchanged. At SDS 0.9 mg/ml (maximal detergent activation), the activities were indistinguishable (C = 90.5 +/- 2.2, I = 91.4 +/- 15.1 micromol Pi/h mg Prot). The analysis of detergent activation of NKA activity is widely used to estimate membrane leakiness in plasma membrane preparations. Our results suggest a higher population of sealed impermeable vesicles in preparations from ischaemic renal tissue.
  
  
  CONCLUSIONS
  The well-known effect of ischaemia on renal cell cytoskeleton could explain the observed changes in the leakiness of membrane vesicles.
authors.affiliation: Consejo Nacional de Investigaciones Científicas y Tcnicas (CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina.
authors.forename: Gabriela
authors.initials: G
authors.lastname: Coux
authors.forename: Maria Mónica
authors.initials: MM
authors.lastname: Elías
authors.forename: Laura
authors.initials: L
authors.lastname: Trumper
mesh_terms: D000818:Animals; D007672:Kidney Cortex / Q000098:blood supply* / Q000201:enzymology*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D015427:Reperfusion Injury / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000502:physiology*; D022161:Transport Vesicles / Q000201:enzymology*
chemical_list: D000254:Sodium-Potassium-Exchanging ATPase