Search results

Sort By:

Limit search:

Nitric oxide - superoxide cooperation in the regulation of renal Na+,K+-ATPase.

100%

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

vol. 51

issue 4

933-942

The aim of this study was to investigate whether endogenous superoxide anion is involved in the regulation of renal Na+,K+-ATPase and ouabain-sensitive H+,K+-ATPase activities. The study was performed in male Wistar rats. Compounds modulating superoxide anion concentration were infused under general anaesthesia into the abdominal aorta proximally to the renal arteries. The activity of ATPases was assayed in isolated microsomal fraction. We found that infusion of a superoxide anion-generating mixture, xanthine oxidase (1 mU/min per kg) + hypoxanthine (0.2 μmol/min per kg), increased the medullary Na+,K+-ATPase activity by 49.5% but had no effect on cortical Na+,K+-ATPase and either cortical or medullary ouabain-sensitive H+,K+-ATPase. This effect was reproduced by elevating endogenous superoxide anion with a superoxide dismutase inhibitor, diethylthiocarbamate. In contrast, a superoxide dismutase mimetic, TEMPOL, decreased the medullary Na+,K+-ATPase activity. The inhibitory effect of TEMPOL was abolished by inhibitors of nitric oxide synthase (L-NAME), soluble guanylate cyclase (ODQ) and protein kinase G (KT5823). The stimulatory effect of diethylthiocarbamate was not observed in animals pretreated with a synthetic cGMP analogue, 8-bromo-cGMP. An inhibitor of NAD(P)H oxidase, apocynin (1 μmol/min per kg), decreased the Na+,K+-ATPase activity in the renal medulla and its effect was prevented by L-NAME, ODQ or KT5823. In contrast, a xanthine oxidase inhibitor, oxypurinol, administered at the same dose was without effect. These data suggest that NAD(P)H oxidase-derived superoxide anion increases Na+,K+-ATPase activity in the renal medulla by reducing the availability of NO. Excessive intrarenal generation of superoxide anion may upregulate medullary Na+,K+-ATPase leading to sodium retention and blood pressure elevation.

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

88%

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.

Refine search results

2 Acta Biochimica Polonica

2 2004

2 Bełtowski J.

2 Borkowska E.

2 Jamroz-Wiśniewska A.

2 Marciniak A.

1 Wójcicka G.

Search results

Nitric oxide - superoxide cooperation in the regulation of renal Na+,K+-ATPase.

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