ATPase Activity In Kidney Research Articles

The effects of nitric oxide synthesis on the Na+,K+-ATPase activity in guinea pig kidney exposed to lipopolysaccharides

Endotoxins (lipopolysaccharides; LPS) are known to cause multiple organ failure, including renal dysfunction. LPS triggers the synthesis and release of cytokines and the vasodilator nitric oxide (NO*). A major contributor to the increase in NO* production is LPS-stimulated expression of inducible nitric oxide synthase (iNOS). This occurs in vasculature and most organs including the kidney. During endotoxemia, NO* and superoxide react spontaneously to form the potent and versatile oxidant peroxynitrite (ONOO-) and the formation of 3-nitrotyrosine (nTyr)-protein adducts is a reliable biomarker of ONOO- generation. Therefore, the present study was aimed at investigating the role of endogenous nitric oxide in regulating Na+,K(+)-ATPase activity in the kidney, and at investigating the possible contribution of reactive nitrogen species (RNS) by measuring of iNOS activity. In addition, the present study was aimed at investigating the relationship between nTyr formation with iNOS and Na+,K(+)-ATPase activities. Previously in our study, nTyr was not detectable in kidney of normal control animals but was detected markedly in LPS exposed animals. In this study, kidney Na+,K(+)-ATPase activity were maximally inhibited 6 h after LPS injection (P:0.000) and LPS treatment significantly increased iNOS activity of kidney (P:0.000). The regression analysis revealed a very close correlation between Na+,K(+)-ATPase activity and nTyr levels of LPS treated animals (r = -0.868, P = 0.001). Na+,K(+)-ATPase activity were also negatively correlated with iNOS activity (r = -0.877, P = 0.001) in inflamed kidney. These data suggest that NO* and ONOO- contribute to the development of oxidant injury. Furthermore, the source of NO* may be iNOS. iNOS are expressed by the kidney, and their activity may increase following LPS administration. In addition, NO* and ONOO- formation inhibited Na+,K(+)-ATPase activity. This results also have strongly suggested that bacterial LPS disturbs activity of membrane Na+,K(+)-ATPase that may be an important component leading to the pathological consequences such as renal dysfunction in which the production of RNS are increased as in the case of LPS challenge.

Freshwater to seawater acclimation of juvenile bull sharks (Carcharhinus leucas): plasma osmolytes and Na+/K+-ATPase activity in gill, rectal gland, kidney and intestine

This study examined the osmoregulatory status of the euryhaline elasmobranch Carcharhinus leucas acclimated to freshwater (FW) and seawater (SW). Juvenile C. leucas captured in FW (3 mOsm l(-1) kg(-1)) were acclimated to SW (980-1,000 mOsm l(-1) kg(-1)) over 16 days. A FW group was maintained in captivity over a similar time period. In FW, bull sharks were hyper-osmotic regulators, having a plasma osmolarity of 595 mOsm l(-1) kg(-1). In SW, bull sharks had significantly higher plasma osmolarities (940 mOsm l(-1) kg(-1)) than FW-acclimated animals and were slightly hypo-osmotic to the environment. Plasma Na(+), Cl(-), K(+), Mg(2+), Ca(2+), urea and trimethylamine oxide (TMAO) concentrations were all significantly higher in bull sharks acclimated to SW, with urea and TMAO showing the greatest increase. Gill, rectal gland, kidney and intestinal tissue were taken from animals acclimated to FW and SW and analysed for maximal Na(+)/K(+)-ATPase activity. Na(+)/K(+)-ATPase activity in the gills and intestine was less than 1 mmol Pi mg(-1) protein h(-1) and there was no difference in activity between FW- and SW-acclimated animals. In contrast Na(+)/K(+)-ATPase activity in the rectal gland and kidney were significantly higher than gill and intestine and showed significant differences between the FW- and SW-acclimated groups. In FW and SW, rectal gland Na(+)/K(+)-ATPase activity was 5.6+/-0.8 and 9.2+/-0.6 mmol Pi mg(-1) protein h(-1), respectively. Na(+)/K(+)-ATPase activity in the kidney of FW and SW acclimated animals was 8.4+/-1.1 and 3.3+/-1.1 Pi mg(-1) protein h(-1), respectively. Thus juvenile bull sharks have the osmoregulatory plasticity to acclimate to SW; their preference for the upper reaches of rivers where salinity is low is therefore likely to be for predator avoidance and/or increased food abundance rather than because of a physiological constraint.

In vitro effect of mercuric chloride on ATPase activity in kidney of the fancy carp Cyprinus carpio

1. The Na +/K +-ATPase and Mg 2+-ATPase activity of fancy carp ( Cyprinus carpio) kidney homogenate without the presence of EDTA was significantly inhibited by mercuric chloride in a concentration-dependent manner. 2. The Na +/K +-ATPase and Mg 2+-ATPase activity of fancy carp ( Cyprinus carpio) kidney homogenate in the presence of EDTA showed no significant change with the increasing concentration of mercuric chloride. 3. The sensitivity of Na +/K +-ATPase to mercuric chloride was greater than that of the Mg 2+-ATPase. 4. In conclusion, the use of EDTA in the determination of the effect of heavy metal on the ATPase activity as a toxicological index should be avoided. Using Na +/K +-ATPase activity as a toxicological index in the studies of heavy metal effect is better than using Mg 2+-ATPase activity.

(Na + + K +)- and Na +-stimulated Mg 2+-dependent ATPase activities in kidney of sea bass ( Dicentrarchus labrax L.)

1. 1. Sea bass kidney microsomal preparations contain two Mg 2+ dependent ATPase activities: the ouabain-sensitive (Na + + K +)-ATPase and an ouabain-insensitive Na +-ATPase, requiring different assay conditions. The (Na + + K +)-ATPase under the optimal conditions of pH 7.0, 100 mM Na +, 25 mM K +, 10 mM Mg 2+, 5 mM ATP exhibits an average specific activity (S.A.) of 59 μmol P i/mg protein per hr whereas the Na +-ATPase under the conditions of pH 6.0, 40 mM Na +, 1.5 mM MgATP, 1 mM ouabain has a maximal S.A. of 13.9 μmol P i/mg protein per hr. 2. 2. The (Na + + K +)-ATPase is specifically inhibited by ouabain and vanadate; the Na +-ATPase specifically by ethacrynic acid and preferentially by frusemide; both activities are similarly inhibited by Ca 2+. 3. 3. The (Na + + K +)-ATPase is specific for ATP and Na +, whereas the Na +-ATPase hydrolyzes other substrates in the efficiency order ATP > GTP > CTP > UTP and can be activated also by K +, NH 4 + or Li +. 4. 4. Minor differences between the two activities lie in the affinity for Na 1, Mg 2+, ATP and in the thermosensitivity. 5. 5. The comparison between the two activities and with what has been reported in the literature only partly agree with our findings. It tentatively suggests that on the one hand two separate enzymes exist which are related to Na + transport and, on the other, a distinct modulation in vitro in different tissues.

Decreased responsiveness to chronic salmon calcitonin treatment in rat kidney and calvaria studied using quantitative enzyme cytochemistry.

Growing rats were treated with daily im doses of salmon calcitonin (sCT) (2, 15 and 100 IU/kg) for various times (1, 4 and 24 weeks). The effects on intracellular enzyme activities in bone and kidney were monitored using quantitative cytochemical methods previously developed for the identification of specific target tissue responses to calcitonins. The basal alkaline phosphatase activities in both kidney and bone were decreased by long-term treatment at all time periods and doses tested. No change was noted in basal Ca ATPase activities in kidney after treatment. The capacity of target tissues in chronically treated and control rats to respond to an acute iv dose of sCT was also compared. Acute provocation tests in treated and control rats showed that the renal alkaline phosphatase response was decreased in the rats receiving long-term treatment. Moreover, the direction of response was reversed in chronically treated rats when bone alkaline phosphatase and renal Ca-dependent ATPase activity was measured after acute provocation with sCT, i.e. bone alkaline phosphatase was stimulated instead of being inhibited and renal Ca ATPase was inhibited instead of being stimulated. The application of quantitative cytochemical techniques has demonstrated intracellular changes in enzyme activities in both kidney and bone. The impaired sCT responsiveness can be detected at shorter times of treatment (1 week) and lower doses (2 IU/kg) than has previously been possible by measurement of indices of mineral metabolism in plasma or urine.

Effect of biogenic amines and gaba on ATPase activities in mouse tissue

ATPase activities were studied in brain, kidney and liver (13,000 x g pellet) fraction from the mouse. Dopamine and norepinephrine added in vitro showed a dose-dependent stimulation of Na + and K + activated and oligomycin sensitive Mg 2+ ATPase activities in brain but not in kidney and liver tissue fractions. GAB and serotonin had no effect on ATPase in brain, but inhibited oligomycin sensitive Mg 2+ ATPase activities in kidney and liver. The relationship between the enhancement of ATPase activity by neurotransmitters in brain and the neuronal excitation is discussed.