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Adrenomedullina

100%

Beltowski J.

nr 1

99-123

Izoprenylacja bialek

63%

Jamroz-Wisniewska A. , Beltowski J.

tom 50

nr 4

316-329

Spectrophotometric method for the determination of renal ouabain-sensitive Hplus, Kplus-ATPase activity

63%

Beltowski J. , Wojcicka G.

nr 2

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 uM in the renal cortex and 1.9 ± 0.4 uM in the renal medulla) and by Sch 28080 (Ki of 1.8 ± 0.5 uM and 2.5 ± 0.9 uM 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.

Biphasic effect of protein kinase C on rat renal cortical Na plus , K plus -ATPase

51%

Beltowski J. , Gorny D. , Marciniak A.

nr 4

Species- and substrate-specific stimulation of human plasma paraoxonase 1 [PON1] activity by high chloride concentration

51%

Beltowski J. , Wojcicka G. , Marciniak A.

2002

tom 49

nr 4

Paraoxonase 1 (PON1), contained in plasma high-density lipoproteins, plays an important role in the protection of plasma lipoproteins and cell membranes from oxidative damage. Previous studies indicate that human PON1 is stimulated by high NaCl concentrations. The aim of this study was to characterize in more detail the effect of salts on serum PON1. Paraoxon-hydrolyzing activity of human serum was stimulated by 81.6% following the addition of 1 M NaCl. The effect of NaCl was dose-dependent between 0.5 and 2 M. PON1 activity toward phenyl acetate was reduced by 1 M NaCl by 55.2%. Both the paraoxon- and phenyl acetate-hydrolysing activity was slightly lower in heparinized plasma than in serum, but NaCl had similar stimulatory and inhibitory effects on these activities, respectively. In rat, rabbit, and mouse, NaCl reduced PON1 activity. KCl had a similar effect on human PON1 as NaCl. Sodium nitrite also stimulated human PON1 but much less effectively than chloride salts. In contrast, sucrose, sodium acetate and sodium lactate had no significant effect. NaBr was a less effective PON1 activator than NaCl, whereas the effect of NaJ was non-significant. The activity of human PON1 toward homogentisic acid lactone and y-decanolactone was unaltered by NaCl. These data indicate that: 1) high concentrations of chlorides stimulate human PON1 activity toward paraoxon but not other substrates, 2) PON1 is inhibited by Cl- in other mammalian species, 3) the potency of human PON1 activation by halogene salts increases with decreasing atomic mass of the halide anion.