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Bidirectional regulation of renal cortical Na+,K+-ATPase by protein kinase C.

100%

Bełtowski J., Marciniak A., Jamroz-Wiśniewska A., Borkowska E., Wójcicka G.

vol. 51

issue 3

757-772

We examined the role of protein kinase C (PKC) in the regulation of Na+,K+- ATPase activity in the renal cortex. Male Wistar rats were anaesthetized and the investigated reagents were infused into the abdominal aorta proximally to the renal arteries. A PKC-activating phorbol ester, phorbol 12,13-dibutyrate (PDBu), had a dose-dependent effect on cortical Na+,K+-ATPase activity. Low dose of PDBu (10-11 mol/kg per min) increased cortical Na+,K+-ATPase activity by 34.2%, whereas high doses (10-9 and 10-8 mol/kg per min) reduced this activity by 22.7% and 35.0%, respectively. PDBu administration caused changes in Na+,K+-ATPase Vmax without affecting K0.5 for Na+, K+ and ATP as well as Ki for ouabain. The effects of PDBu were abolished by PKC inhibitors, staurosporine, GF109203X, and Gö 6976. The inhibitory effect of PDBu was reversed by pretreatment with inhibitors of cytochrome P450-dependent arachidonate metabolism, ethoxyresorufin and 17-octadecynoic acid, inhibitors of phosphatidylinositol 3-kinase (PI3K), wortmannin and LY294002, and by actin depolymerizing agents, cytochalasin D and latrunculin B. These results suggest that PKC may either stimulate or inhibit renal cortical Na+,K+-ATPase. The inhibitory effect is mediated by cytochrome P450-dependent arachidonate metabolites and PI3K, and is caused by redistribution of the sodium pump from the plasma membrane to the inactive intracellular pool.

Regulation of renal Na+,K+ -ATPase and ouabain-sensitive H+,K+ -ATPase by the cyclic AMP-protein kinase A signal transduction pathway.

75%

Bełtowski J., Marciniak A., Wójcicka G., Górny D.

2003

vol. 50

issue 1

103-114

We investigated the effect of the cyclic AMP-protein kinase A (PKA) signalling pathway on renal Na+,K+-ATPase and ouabain-sensitive H+,K+-ATPase. Male Wistar rats were anaesthetized and catheter was inserted through the femoral artery into the abdominal aorta proximally to the renal arteries for infusion of the investigated substances. Na+,K+-ATPase activity was measured in the presence of Sch 28080 to block ouabain-sensitive H+,K+-ATPase and improve specificity of the assay. Dibutyryl-cyclic AMP (db-cAMP) administered at a dose of 10-17 mol/kg per min and 10-6 mol/kg per min increased Na+,K+-ATPase activity in the renal cortex by 34% and 42%, respectively, and decreased it in the renal medulla by 30% and 44%, respectively. db-cAMP infused at 10-6 mol/kg per min increased the activity of cortical ouabain-sensitive H+,K+-ATPase by 33%, and medullary ouabain-sensitive H+,K+-ATPase by 30%. All the effects of db-cAMP were abolished by a specific inhibitor of protein kinase A, KT 5720. The stimulatory effect on ouabain-sensitive H+,K+-ATPase and on cortical Na+,K+-ATPase was also abolished by brefeldin A which inhibits the insertion of proteins into the plasma membranes, whereas the inhibitory effect on medullary Na+,K+-ATPase was partially attenuated by 17-octadecynoic acid, an inhibitor of cytochrome P450-dependent arachidonate metabolism. We conclude that the cAMP-PKA pathway stimulates Na+,K+-ATPase in the renal cortex as well as ouabain-sensitive H+,K+-ATPase in the cortex and medulla by a mechanism requiring insertion of proteins into the plasma membrane. In contrast, medullary Na+,K+-ATPase is inhibited by cAMP through a mechanism involving cytochrome P450-dependent arachidonate metabolites.

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2 Acta Biochimica Polonica

1 2004

1 2003

2 Bełtowski J.

2 Marciniak A.

2 Wójcicka G.

1 Borkowska E.

1 Górny D.

1 Jamroz-Wiśniewska A.

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Bidirectional regulation of renal cortical Na+,K+-ATPase by protein kinase C.

Regulation of renal Na+,K+ -ATPase and ouabain-sensitive H+,K+ -ATPase by the cyclic AMP-protein kinase A signal transduction pathway.