Activated neutrophils inhibit Na(+)-K(+)-ATPase in canine renal basolateral membrane.
To examine the effects of activated neutrophils (PMNs) on Na(+)-K(+)-ATPase, phorbol 12-myristate 13-acetate (PMA)-stimulated PMNs were incubated with canine renal cortical basolateral membrane (BLM), and BLM ouabain-sensitive Na(+)-K(+)-ATPase activity was subsequently quantified. Na(+)-K(+)-ATPase activity decreased to 40.0 +/- 8.7% (SE) of control in the presence of activated PMNs, from 0.89 +/- 0.12 to 0.34 +/- 0.05 mumol Pi.mg protein-1.min-1. This inhibition coincided with a decrease in the apparent Michaelis constant (Km) for ATP from 0.18 +/- 0.02 to 0.05 +/- 0.01 mM. Inclusion of catalase (CAT) and superoxide dismutase (SOD) in the BLM/PMN/PMA incubation mixture resulted in partial preservation of enzyme activity, with an increase to 57.0 +/- 4.6% of control with CAT alone and to 70.0 +/- 5.3% with both CAT and SOD. SOD alone had no protective effect. Neither the myeloperoxidase inhibitor azide nor the hypochlorous acid scavenger L-methionine preserved enzyme activity. Hydroxyl radical scavengers and iron chelators were also ineffective in attenuating Na(+)-K(+)-ATPase inhibition by activated PMNs. These results indicate that activated PMNs mediate a decrease in BLM Na(+)-K(+)-ATPase activity characterized by a reduction in maximum velocity and Km for ATP that appears to be mediated in part by reactive oxygen metabolites.
Julin
C M
CM
Department of Pediatrics, University of Wisconsin School of Medicine, Madison 53792.
Zimmerman
J J
JJ
Sundaram
V
V
Chobanian
M C
MC
D000818:Animals; D001386:Azides / Q000494:pharmacology; D002462:Cell Membrane / Q000201:enzymology*; D003497:Cyclic N-Oxides / Q000494:pharmacology; D003676:Deferoxamine / Q000494:pharmacology; D004285:Dogs; D016166:Free Radical Scavengers; D005609:Free Radicals / Q000378:metabolism; D006801:Humans; D006878:Hydroxides / Q000378:metabolism; D017665:Hydroxyl Radical; D007672:Kidney Cortex / Q000201:enzymology*; D007700:Kinetics; D009247:NADH, NADPH Oxidoreductases / Q000097:blood; D019255:NADPH Oxidases; D009504:Neutrophils / Q000187:drug effects / Q000502:physiology*; D010042:Ouabain / Q000494:pharmacology; D010618:Phenanthrolines / Q000494:pharmacology; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors*; D013481:Superoxides / Q000097:blood; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D001386:Azides; D003497:Cyclic N-Oxides; D016166:Free Radical Scavengers; D005609:Free Radicals; D006878:Hydroxides; D010618:Phenanthrolines; D013481:Superoxides; D017665:Hydroxyl Radical; D010042:Ouabain; C017245:5,5-dimethyl-1-pyrroline-1-oxide; D009247:NADH, NADPH Oxidoreductases; D019255:NADPH Oxidases; D000254:Sodium-Potassium-Exchanging ATPase; D003676:Deferoxamine; D013755:Tetradecanoylphorbol Acetate