title: Ischemic conditioning prevents Na,K-ATPase dissociation from the cytoskeletal cellular fraction after repeat renal ischemia in rats.
abstract: Recent studies have suggested that heat shock proteins (HSPs) are involved in the restoration of the cytoskeletal anchorage of Na,K-ATPase after renal ischemia. To determine their role in ischemic conditioning, we investigated whether cytoskeletal Na,K-ATPase was stabilized during repeat ischemia concurrent with 25-kD and 70-kD HSPs induction. Anesthetized rats either underwent single unilateral renal ischemia or were conditioned with bilateral renal ischemia and, after 18 h of reflow, were then subjected to repeat unilateral renal ischemia. Renal cortex was harvested, and effects of single versus repeat ischemia were compared by Triton X-100 extraction, by immunohistochemistry, and by an in vitro assay of Na,K-ATPase association with isolated cytoskeletal fractions. In contrast to single ischemia, repeat ischemia did not result in increased Triton X-100 extractability of Na,K-ATPase. Levels of 25-kD and 70-kD HSPs were significantly induced by ischemic conditioning and redistributed into the cytoskeletal fraction after single and repeat ischemia. Immunohistochemistry also showed significant disruption of Na,K-ATPase within proximal tubules only after a single episode of ischemia, whereas repeat ischemia did not alter the pattern of restored Na,K-ATPase localization in conditioned renal cortex. The preserved association of Na,K-ATPase with the cytoskeletal fraction of conditioned renal cortex was effectively abolished in vitro by addition of antibodies against 25-kD or 70-kD HSP. These results suggest that 25-kD and 70-kD HSPs induced by ischemic conditioning stabilize the cytoskeletal anchorage of Na,K-ATPase during repeat renal ischemia.
authors.affiliation: Kinderdialyse, Department of Pediatrics, AKH Wien, A-1090 Vienna, Austria. christoph.aufricht@akh-wien.ac.at
authors.forename: Christoph
authors.initials: C
authors.lastname: Aufricht
authors.forename: Bettina
authors.initials: B
authors.lastname: Bidmon
authors.forename: Dagmar
authors.initials: D
authors.lastname: Ruffingshofer
authors.forename: Heinz
authors.initials: H
authors.lastname: Regele
authors.forename: Kurt
authors.initials: K
authors.lastname: Herkner
authors.forename: Norman J
authors.initials: NJ
authors.lastname: Siegel
authors.forename: Michael
authors.initials: M
authors.lastname: Kashgarian
authors.forename: Scott K
authors.initials: SK
authors.lastname: Van Why
mesh_terms: D000818:Animals; D002458:Cell Fractionation; D003599:Cytoskeleton; D055551:HSP27 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D006360:Heat-Shock Proteins; D007511:Ischemia / Q000378:metabolism* / Q000503:physiopathology; D019194:Ischemic Preconditioning; D007672:Kidney Cortex / Q000201:enzymology* / Q000503:physiopathology; D008163:Luminescent Measurements; D008297:Male; D009363:Neoplasm Proteins / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*
chemical_list: D055551:HSP27 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; C486114:Hspb1 protein, rat; D009363:Neoplasm Proteins; D000254:Sodium-Potassium-Exchanging ATPase