Nitric oxide reduces the molecular activity of Na+,K+-ATPase in opossum kidney cells. Kidney Int 1999 Aug;56(2):627-34
Date
08/05/1999Pubmed ID
10432402DOI
10.1046/j.1523-1755.1999.00583.xScopus ID
2-s2.0-0032815392 (requires institutional sign-in at Scopus site) 62 CitationsAbstract
BACKGROUND: Nitric oxide (NO) directly inhibits fluid and solute reabsorption in the proximal tubule. In the present study, we investigated the effect of NO on the Na+, K+-ATPase of opossum kidney (OK) cells, a proximal tubule cell line, and its mechanisms.
METHODS: Na+,K+-ATPase activity in the membrane fraction of OK cells was measured as the ouabain-sensitive ATP hydrolytic activity. The enzyme unit number on intact cells was measured by ouabain-binding assay.
RESULTS: Incubation with 0.5 mM sodium nitroprusside (SNP), a NO donor, for two hours inhibited the catalytic activity of the membrane-associated Na+,K+-ATPase in OK cells to 65.5 +/- 9.7% of control (N = 6, P < 0.05 vs. control). This effect of SNP was concentration- and time-dependent. The NO scavenger hemoglobin blunted, while another NO donor spermine NONOate (5 microM) mimicked this effect of SNP. At all concentrations and time points tested, SNP did not alter the molecular number of Na+,K+-ATPase on intact OK cells, indicating that NO inhibited the molecular activity of Na+,K+-ATPase. The soluble guanylate cyclase inhibitor, 1H-[1,2,4]oxadiazolo-[4, 3-a]quinoxalin-1-one (ODQ), blunted the inhibitory effect of SNP on the Na+,K+-ATPase activity. An exogenous cGMP analog similarly inhibited the Na+,K+-ATPase activity. Neither lipid soluble antioxidants vitamin E/probucol or thiol group compound DL-dithiothreitol (DTT) altered the inhibitory effect of SNP on the Na+,K+-ATPase activity.
CONCLUSIONS: NO inhibited the molecular activity of the Na+,K+-ATPase of the OK proximal tubule cell line probably via cGMP-dependent mechanisms.
Author List
Liang M, Knox FGMESH terms used to index this publication - Major topics in bold
AnimalsAnticholesteremic Agents
Antihypertensive Agents
Cells, Cultured
Cyclic GMP
Enzyme Inhibitors
Kidney Tubules, Proximal
Lipid Peroxidation
Nitric Oxide
Nitroprusside
Opossums
Ouabain
Probucol
Protein Binding
Signal Transduction
Sodium-Potassium-Exchanging ATPase
Vitamin E