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    Wyświetlanie 1-8 z 8
    Tytuł:
    Spectrophotometric assay of renal ouabain-resistant Na+-ATPase and its regulation by leptin and dietary-induced obesity.
    Autorzy:
    Bełtowski, Jerzy
    Jamroz-Wiśniewska, Anna
    Nazar, Jarosław
    Wójcicka, Grażyna
    Powiązania:
    https://bibliotekanauki.pl/articles/1041514.pdf
    Data publikacji:
    2004
    Wydawca:
    Polskie Towarzystwo Biochemiczne
    Tematy:
    leptin
    obesity
    Na+,K+-ATPase
    Na+-ATPase
    Opis:
    Apart from Na+,K+-ATPase, a second sodium pump, Na+-stimulated, K+-independent ATPase (Na+-ATPase) is expressed in proximal convoluted tubule of the mammalian kidney. The aim of this study was to develop a method of Na+-ATPase assay based on the method previously used by us to measure Na+,K+-ATPase activity (Acta Biochim Polon.; 2002, 49: 515-27). The ATPase activity was assayed as the amount of inorganic phosphate liberated from ATP by isolated microsomal fraction. Na+-ATPase activity was calculated as the difference between the activities measured in the presence and in the absence of 50 mM NaCl. Na+-ATPase activity was detected in the renal cortex (3.5 ± 0.2 μmol phosphate/h per mg protein), but not in the renal medulla. Na+-ATPase was not inhibited by ouabain or an H+,K+-ATPase inhibitor, Sch 28080, but was almost completely blocked by 2 mM furosemide. Leptin administered intraperitoneally (1 mg/kg) decreased the Na+,K+-ATPase activity in the renal medulla at 0.5 and 1 h by 22.1% and 27.1%, respectively, but had no effect on Na+-ATPase in the renal cortex. Chronic hyperleptinemia induced by repeated subcutaneous leptin injections (0.25 mg/kg twice daily for 7 days) increased cortical Na+,K+-ATPase, medullary Na+,K+-ATPase and cortical Na+-ATPase by 32.4%, 84.2% and 62.9%, respectively. In rats with dietary-induced obesity, the Na+,K+- ATPase activity was higher in the renal cortex and medulla by 19.7% and 34.3%, respectively, but Na+-ATPase was not different from control. These data indicate that both renal Na+-dependent ATPases are separately regulated and that up-regulation of Na+-ATPase may contribute to Na+ retention and arterial hypertension induced by chronic hyperleptinemia.
    Źródło:
    Acta Biochimica Polonica; 2004, 51, 4; 1003-1014
    0001-527X
    Pojawia się w:
    Acta Biochimica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Spectrophotometric method for the determination of renal ouabain-sensitive H+,K+ -ATPase activity.
    Autorzy:
    Bełtowski, Jerzy
    Wójcicka, Grażyna
    Powiązania:
    https://bibliotekanauki.pl/articles/1043791.pdf
    Data publikacji:
    2002
    Wydawca:
    Polskie Towarzystwo Biochemiczne
    Tematy:
    leptin
    kidney
    H+,K+-ATPase
    ouabain
    Sch 28080
    Na+,K+-ATPase
    Opis:
    The aim of this work was to develop a method for renal H+,K+-ATPase measurement based on the previously used Na+,K+-ATPase assay (Bełtowski et al.: J Physiol Pharmacol.; 1998, 49: 625-37). ATPase activity was assessed by measuring the amount of inorganic phosphate liberated from ATP by isolated microsomal fraction. Both ouabain-sensitive and ouabain-resistant K+-stimulated and Na+-independent ATPase activity was detected in the renal cortex and medulla. These activities were blocked by 0.2 mM imidazolpyridine derivative, Sch 28080. The method for ouabain- sensitive H+,K+-ATPase assay is characterized by good reproducibility, linearity and recovery. In contrast, the assay for ouabain-resistant H+,K+-ATPase was unsatisfactory, probably due to low activity of this enzyme. Ouabain-sensitive H+,K+-ATPase was stimulated by K+ with Km of 0.26 ± 0.04 mM and 0.69 ± 0.11 mM in cortex and medulla, respectively, and was inhibited by ouabain (Ki of 2.9 ± 0.3 μM in the renal cortex and 1.9 ± 0.4 μM in the renal medulla) and by Sch 28080 (Ki of 1.8 ± 0.5 μM and 2.5 ± 0.9 μM in cortex and medulla, respectively). We found that ouabain-sensitive H+,K+-ATPase accounted for about 12% of total ouabain-sensitive activity in the Na+,K+-ATPase assay. Therefore, we suggest to use Sch 28080 during Na+,K+-ATPase measurement to block H+,K+-ATPase and improve the assay specificity. Leptin administered intraperitoneally (1 mg/kg) decreased renal medullary Na+,K+-ATPase activity by 32.1% at 1 h after injection but had no effect on H+,K+-ATPase activity suggesting that the two renal ouabain-sensitive ATPases are separately regulated.
    Źródło:
    Acta Biochimica Polonica; 2002, 49, 2; 515-527
    0001-527X
    Pojawia się w:
    Acta Biochimica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Nitric oxide - superoxide cooperation in the regulation of renal Na+,K+-ATPase.
    Autorzy:
    Bełtowski, Jerzy
    Marciniak, Andrzej
    Jamroz-Wiśniewska, Anna
    Borkowska, Ewelina
    Powiązania:
    https://bibliotekanauki.pl/articles/1041505.pdf
    Data publikacji:
    2004
    Wydawca:
    Polskie Towarzystwo Biochemiczne
    Tematy:
    H+,K+-ATPase
    Sch 28080
    superoxide anion
    Na+,K+-ATPase
    nitric oxide
    oxidative stress
    Opis:
    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.
    Źródło:
    Acta Biochimica Polonica; 2004, 51, 4; 933-942
    0001-527X
    Pojawia się w:
    Acta Biochimica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The involvement of Na+/K+-ATPase in the development of platelet procoagulant response
    Autorzy:
    Tomasiak, Marian
    Stelmach, Halina
    Rusak, Tomasz
    Ciborowski, Michał
    Radziwon, Piotr
    Powiązania:
    https://bibliotekanauki.pl/articles/1041052.pdf
    Data publikacji:
    2007
    Wydawca:
    Polskie Towarzystwo Biochemiczne
    Tematy:
    cardiac glycosides
    ouabain
    Na+/K+-ATPase
    atrial fibrillation
    platelets
    procoagulant activity
    Opis:
    In circulation, platelets may come into contact with both exogenous (cardiac glycoside treatment) and endogenously produced inhibitors of Na+/K+-ATPase. We examined whether blocking of platelet Na+/K+-ATPase by ouabain results in generation of procoagulant activity. It was shown that an in vitro treatment of platelets with ouabain (20-200 µM for 20 to 60 min) is associated with an intracellular accumulation of sodium ([Na+]i), generation of a weak calcium signal, and expression of procoagulant activity. The ouabain-induced procoagulant response was dose- and time-related, less pronounced than that evoked by collagen and similar to that produced by gramicidin, not affected by EDTA or aspirin, and strongly reduced in the absence of extracellular Na+ or by hyperosmolality. Flow cytometry studies revealed that ouabain treatment results in a unimodal left shift in the forward and side scatter of the entire platelet population indicating morphological changes of the plasma membrane. The shift was dose related, weaker than that evoked by collagen and similar to that produced by gramicidin. Ouabain-treated platelets express phosphatidylserine (PS). The ouabain-evoked PS expression was dose- and time-dependent, weaker than that produced by collagen and similar to that evoked by gramicidin. Electronic cell sizing measurements showed a dose-dependent increase in mean platelet volume upon treatment with ouabain. Hypoosmotically-evoked platelet swelling resulted in the appearance of procoagulant activity. Thromboelastography measurements indicate that, in whole blood, nanomolar (50-1000 nM, 15 min) concentrations of ouabain significantly accelerate the rate of clot formation initiated by contact and high extracellular concentration of calcium. We conclude that inefficiently operating platelet Na+/K+-ATPase results in a rise in [Na+]i. An increase in [Na+]i and the swelling associated with it may produce PS exposure and a rise in membrane curvature leading to the generation of a procoagulant activity.
    Źródło:
    Acta Biochimica Polonica; 2007, 54, 3; 625-639
    0001-527X
    Pojawia się w:
    Acta Biochimica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Protective role of L-methionine against free radical damage of rat brain synaptosomes
    Autorzy:
    Slyshenkov, Vyacheslav
    Shevalye, Anna
    Liopo, Anton
    Wojtczak, Lech
    Powiązania:
    https://bibliotekanauki.pl/articles/1043695.pdf
    Data publikacji:
    2002
    Wydawca:
    Polskie Towarzystwo Biochemiczne
    Tematy:
    (Na+,K+)-ATPase
    oxygen free radicals
    brain
    synaptosomes
    tert-butylhydroperoxide
    L-methionine
    Opis:
    Incubation of rat brain synaptosomal/mitochondrial fraction with tert-butylhydroperoxide resulted in accumulation of the lipid peroxidation product, conjugated dienes, damage of the synaptosomal membrane as evidenced by leakage of lactate dehydrogenase, and decrease of the total content of glutathione and of the GSH/GSSG ratio. This treatment also produced a considerable decrease of the ouabain-sensitive ATPase activity and a much smaller diminution of the activities of glutathione reductase and glutathione transferase. Preincubation of the synaptosomal/mitochondrial fraction with 0.5 or 1.0 mM L-methionine significantly protected against lipid peroxidation, membrane damage and changes in the glutathione system produced by low (1 mM) concentrations of tert-butylhydroperoxide and completely prevented inactivation of ouabain-sensitive ATPase, glutathione reductase and glutathione transferase by such treatment. The importance of L-methionine in antioxidant protection is discussed.
    Źródło:
    Acta Biochimica Polonica; 2002, 49, 4; 907-916
    0001-527X
    Pojawia się w:
    Acta Biochimica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Time-dependent effect of leptin on renal Na+,K+-ATPase activity
    Autorzy:
    Marciniak, Andrzej
    Jamroz-Wiśniewska, Anna
    Borkowska, Ewelina
    Bełtowski, Jerzy
    Powiązania:
    https://bibliotekanauki.pl/articles/1041321.pdf
    Data publikacji:
    2005
    Wydawca:
    Polskie Towarzystwo Biochemiczne
    Tematy:
    mitogen-activated protein kinases
    leptin
    obesity
    arterial hypertension
    hydrogen peroxide
    Na+,K+-ATPase
    Opis:
    Leptin, secreted by adipose tissue, is involved in the pathogenesis of arterial hypertension, however, the mechanisms through which leptin increases blood pressure are incompletely elucidated. We investigated the effect of leptin, administered for different time periods, on renal Na+,K+-ATPase activity in the rat. Leptin was infused under anesthesia into the abdominal aorta proximally to the renal arteries for 0.5-3 h. Leptin administered at doses of 1 and 10 µg/min per kg for 30 min decreased the Na+,K+-ATPase activity in the renal medulla. This effect disappeared when the hormone was infused for ≥1 h. Leptin infused for 3 h increased the Na+,K+-ATPase activity in the renal cortex and medulla. The stimulatory effect was abolished by a specific inhibitor of Janus kinases (JAKs), tyrphostin AG490, as well as by an NAD(P)H oxidase inhibitor, apocynin. Leptin increased urinary excretion of hydrogen peroxide (H2O2) between 2 and 3 h of infusion. The effect of leptin on renal Na+,K+-ATPase and urinary H2O2 was augmented by a superoxide dismutase mimetic, tempol, and was abolished by catalase. In addition, infusion of H2O2 for 30 min increased the Na+,K+-ATPase activity. Inhibitors of extracellular signal regulated kinases (ERKs), PD98059 or U0126, prevented Na+,K+-ATPase stimulation by leptin and H2O2. These data indicate that leptin, by acting directly within the kidney, has a delayed stimulatory effect on Na+,K+-ATPase, mediated by JAKs, H2O2 and ERKs. This mechanism may contribute to the abnormal renal Na+ handling in diseases associated with chronic hyperleptinemia such as diabetes and obesity.
    Źródło:
    Acta Biochimica Polonica; 2005, 52, 4; 803-809
    0001-527X
    Pojawia się w:
    Acta Biochimica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Regulation of renal Na+,K+ -ATPase and ouabain-sensitive H+,K+ -ATPase by the cyclic AMP-protein kinase A signal transduction pathway.
    Autorzy:
    Bełtowski, Jerzy
    Marciniak, Andrzej
    Wójcicka, Grażyna
    Górny, Dionizy
    Powiązania:
    https://bibliotekanauki.pl/articles/1043651.pdf
    Data publikacji:
    2003
    Wydawca:
    Polskie Towarzystwo Biochemiczne
    Tematy:
    kidney
    cyclic AMP
    protein kinase A
    cytochrome P450-dependent arachidonate metabolites
    Na+,K+ -ATPase
    H+,K+ -ATPase
    Opis:
    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.
    Źródło:
    Acta Biochimica Polonica; 2003, 50, 1; 103-114
    0001-527X
    Pojawia się w:
    Acta Biochimica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Bidirectional regulation of renal cortical Na+,K+-ATPase by protein kinase C.
    Autorzy:
    Bełtowski, Jerzy
    Marciniak, Andrzej
    Jamroz-Wiśniewska, Anna
    Borkowska, Ewelina
    Wójcicka, Grażyna
    Powiązania:
    https://bibliotekanauki.pl/articles/1041555.pdf
    Data publikacji:
    2004
    Wydawca:
    Polskie Towarzystwo Biochemiczne
    Tematy:
    phosphatidylinositol-3-kinase
    protein kinase C
    cytochrome P450-dependent arachidonate metabolites
    Na+,K+-ATPase
    Opis:
    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.
    Źródło:
    Acta Biochimica Polonica; 2004, 51, 3; 757-772
    0001-527X
    Pojawia się w:
    Acta Biochimica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-8 z 8

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