Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.6.1.3 (ATPase)
65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Previous studies have indicated that ornithine decarboxylase (ODC) may be involved in the stimulation of Na+/K(+)-ATPase activity by arginine vasopressin (AVP) in the rat renal medullary thick ascending limb of Henle's loop. The present study was aimed at establishing the role of the polyamines, the conversion products of ODC activity, in the stimulation of Na+/K(+)-ATPase by AVP. Using cytochemical methods, we have demonstrated an increase in Na+/K(+)-ATPase activity after stimulation with putrescine, spermidine and spermine (each 1 mmol/l) for 2.5, 2 and 1.5 min respectively. The specific inhibitors of spermidine and spermine synthase, bis-cyclohexylammonium sulphate and N-alkylated-1,3-diaminopropane respectively, inhibited the stimulation of Na+/K(+)-ATPase by AVP, this inhibition being reversed by spermine. These findings suggest that polyamines are involved in the stimulus-response coupling of the hormone-mediated response.
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PMID:Stimulation of Na+/K(+)-ATPase activity by polyamines in the rat renal medullary cells of the thick ascending limb of Henle's loop. 217 62

The development of symptomatic hyponatremia in otherwise healthy young women can result in death or permanent brain damage. The reasons for the increased female susceptibility to complications from hyponatremia are, however, unclear. To determine whether mechanisms that normally defend the brain against damage from hyponatremia are less effective in females than males, we studied both sodium transport in the brains of hyponatremic male and female rats and the effects of parenteral arginine vasopressin on brain high-energy phosphate metabolism and intracellular pH. Basal sodium uptake in synaptosomes prepared from whole brain of females (2.20 nmol/mg protein) and males (2.98 nmol/mg protein) was not statistically different. In contrast, veratridine-stimulated sodium uptake in female brain was 8.20 nmol/mg protein, which was 86% greater (P less than 0.001) than the 6.12 nmol/mg protein observed for male brain. Additionally, sodium uptake between 5 and 60 s was significantly (P less than 0.001) greater in females than males. These data suggest that the Na+-K+-adenosinetriphosphatase (ATPase) pump function in female rat brain synaptosomes is less effective than in males. To determine whether arginine vasopressin, a peptide hormone that promotes water retention by the kidney, had any effects on cerebral energy metabolism, we performed phosphorus-31 (31P) magnetic resonance spectroscopy (MRS) studies on the brain of normonatremic young adult male and female rats subjected to high (20 IU) peripheral doses of arginine vasopressin. We found decreased high-energy phosphate generation, elevated inorganic phosphate, and intracellular acidosis after arginine vasopressin administration in females but not males.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Sex differences result in increased morbidity from hyponatremia in female rats. 253 58

The effect of extracellular calcium (Ca2+) on the cellular action of arginine vasopressin (AVP) was examined using an Na+, K+-ATPase inhibitor in rat renal papillary collecting tubule cells in culture. The pretreatment of cells with ouabain enhanced basal and AVP-induced cAMP production in a dose-dependent manner. The augmentation by ouabain of cellular cAMP production in response to AVP was totally abolished by co-treatment with cobalt, lanthanum, verapamil or Ca2+-free medium containing 1 mmol EGTA/l, each blocking cellular Ca2+ uptake by different mechanisms. Two other findings indicated that ouabain directly stimulated cellular Ca2+ mobilization; namely, that ouabain significantly increased 45Ca2+ influx and cellular free Ca2+ concentration [( Ca2+]i) determined by Fura-2 fluorescence. The ouabain-induced increase in [Ca2+]i was completely blocked by either cobalt or Ca2+-free medium containing 1 mmol EGTA/l. AVP at 0.1 mumol/l increased [Ca2+]i to 177.1 +/- 26.2 nmol/l from 92.2 +/- 8.0 nmol/l (P less than 0.01) in renal papillary collecting tubule cells, and ouabain significantly enhanced the AVP-induced increase in [Ca2+]i. The increase of cellular free Ca2+ induced by ouabain probably binds to calmodulin to form an active complex of Ca2+-calmodulin in the cell, since two chemically dissimilar antagonists of calmodulin attenuated the enhancement by ouabain of cAMP production in response to AVP. These results therefore indicate that ouabain increases cellular Ca2+ uptake and enhances AVP-induced cellular free Ca2+ mobilization and its own second messenger cAMP production in renal papillary collecting tubule cells, and that extracellular Ca2+ is an important source for ouabain-mobilized cellular Ca2+.
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PMID:Effect of ouabain on cellular free calcium and cellular cyclic AMP production in response to arginine vasopressin in rat renal papillary collecting tubule cells in culture. 254 11

Heterogeneity in Madin-Darby canine kidney (MDCK) epithelial cells has been reported, however, its details have not been well described. In the present study, we show that subclones obtained from a MDCK cell line could be divided into two morphologically and biochemically distinct cell types with different hormonal responsiveness. Clones of the first type, motile clones, which had extended and flattened cytoplasm, were devoid of carbonic anhydrase activity. Clones of the second type, nonmotile clones, formed colonies of cuboidal cells and showed carbonic anhydrase activity. Motile clones synthesized cAMP in response to arginine vasopressin, prostaglandin E1, and isoproterenol but not glucagon. In contrast, nonmotile clones responded to all of these hormones. These findings suggest MDCK cells have multiple cellular origins. The motile clones have characteristics similar to the principal cells of the collecting system, whereas the nonmotile clones may be derived from the thick ascending limb or the intercalated cell. Our studies also demonstrate a significant influence of culture condition on MDCK cellular behavior (carbonic anhydrase activity, Na+/K+-ATPase activity and vasopressin responsiveness). Therefore, physiologic and biochemical experiments with MDCK cells must be interpreted with reservations about cellular heterogeneity as well as differences induced by culture conditions.
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PMID:Characterization of subclones of Madin-Darby canine kidney renal epithelial cell line. 255 8

The effects of arginine vasopressin (AVP) on Na+,K+-ATPase activity in human erythrocytes have been studied. AVP stimulates enzymatic activity with no effect on transport activity. Since the enzymatic reaction with AVP can proceed in the absence of ion transport, it may explain the discrepancies between the in vivo and in vitro effects observed with the hormone on Na+ processing by the kidney.
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PMID:[Stimulation of the hydrolytic activity of Na+,K+-ATPase in the erythrocytes by arginine vasopressin]. 282 90

Tissue culture media from incubations of fragments of rat brain were collected and partially purified. These supernatants were effective in inhibiting the Na+-K+ pump as indicated by a 77% reduction of ouabain-sensitive 86Rb+ uptake into human erythrocytes. Release of the Na+-K+-ATPase inhibitor depended on the amount of tissue, the temperature, and the length of incubation. Atrial natriuretic peptide (ANP) injected intravenously, or included (10(-8) M) in the in vitro incubation of brain tissue, decreased the release of the Na+-K+-ATPase inhibitor by 74 and 42%, respectively. Control experiments using the neuropeptide arginine vasopressin showed no effect on release of the inhibitor. These studies indicate that ANP is capable of regulating the release from brain of a Na+-K+-ATPase inhibitor with similar chromatographic characteristics to the one previously obtained from extraction of bovine hypothalamus and raise the possibility that the two factors are interrelated in the regulation of fluid and electrolyte balance.
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PMID:Atrial natriuretic peptide regulates release of Na+-K+-ATPase inhibitor from rat brain. 283 11

The medullary portion of the thick ascending limb of the loop of Henle (TALH) has one of the highest concentrations of Na+-K+-ATPase found in mammalian tissues, reflecting the importance of this nephron segment in the regulation of extracellular fluid volume, as active sodium transport is driven by Na+-K+-ATPase. We have isolated cells derived primarily from the TALH of the outer medulla of rabbit kidney and have identified a cytochrome P450-dependent monooxygenase system which metabolizes arachidonic acid to two biologically active oxygenated peaks, each containing two or more products. One of the peaks potently inhibits cardiac Na+-K+-ATPase and the other relaxes blood vessels. We report that formation of these oxygenated arachidonate metabolites is stimulated by arginine vasopressin and salmon calcitonin. In TALH cells obtained from rabbits made hypertensive by aortic constriction there was a selective increase in P1 and P2 formation compared to other renomedullary cells.
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PMID:Arachidonic acid metabolites and blood pressure control. 284 19

The function of the nephron, the anatomical unit of the kidney, is segmented; at least 12 segments have been identified that differ in their morphology, transport properties and hormonal responsiveness. The medullary portion of the thick ascending limb of the loop of Henle (mTALH) has one of the highest concentrations of (Na+ + K+)ATPase found in mammalian tissues, reflecting the importance of this nephron segment in the regulation of extracellular fluid volume, as active sodium transport is driven by (Na+ + K+)ATPase. Here, in cells derived primarily from the mTALH of the outer medulla of rabbit kidney, we have identified a cytochrome P450-dependent monooxygenase system which metabolizes arachidonic acid to two biologically active oxygenated products; one of the products inhibits (Na+ + K+)ATPase and the other relaxes blood vessels. We report that formation of these oxygenated arachidonate metabolites is stimulated by arginine vasopressin (AVP) and salmon calcitonin (SCT).
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PMID:Renal cytochrome P450-related arachidonate metabolite inhibits (Na+ + K+)ATPase. 298 8

The effect of rat prolactin on rat renal Na+-K+-ATPase activity was investigated by a cytochemical technique. Rat prolactin caused stimulation of Na+-K+-ATPase activity only in the outer medulla of the kidney, and not in renal cortical structures. Peak enzyme activity in cultured rat renal segments occurred after tissue had been exposed to rat prolactin for 2 min, and the time of maximal stimulation did not vary with the concentration of prolactin. There was a curvilinear response in Na+-K+-ATPase activity over the rat prolactin concentration range, 0.04-40 ng/l, but higher prolactin concentrations caused inhibition of enzyme activity. Na+-K+-ATPase response was totally blocked by specific rat prolactin antiserum. Human prolactin had no consistent effect on rat medullary Na+-K+-ATPase activity. Addition of specific tri-iodothyronine and arginine vasopressin antisera to rat prolactin was without effect, confirming that the stimulatory action of rat prolactin on Na+-K+-ATPase was not due to contamination with these hormones which are known to stimulate this enzyme.
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PMID:Prolactin stimulates Na+-K+-ATPase activity located in the outer renal medulla of the rat. 300 25

A cytochemical assay has been developed to measure human plasma arginine vasopressin. It is based on the stimulation of Na+-K+, ATPase activity located in the outer medulla of the rat kidney, and is capable of detecting very low plasma arginine vasopressin concentrations, limit of detection 0.01 pmol/l. Specificity for vasopressin stimulation of the enzyme is conferred on the assay by the use of specific vasopressin antiserum. Index of precision of the assay is 0.21. Degradation of arginine vasopressin in plasma in inhibited by phenanthroline. Samples may be stored up to 8 weeks at -70 degrees C. Intra- and inter-assay coefficients of variation were 22% (n = 8) and 104% (n = 12), respectively. A sustained water load in eight healthy male adults caused a fall in plasma osmolality from a basal of 286.5 +/- 2.0 (mean +/- SEM) to 279.2 +/- 2.4 mmol/kg after the load (P less than 0.001), which was associated with a reduction in urine osmolality from 867 +/- 54 to 69 +/- 3 mmol/kg. Plasma immunoreactive arginine vasopressin fell from 1.3 +/- 0.3 pmol/l to become undetectable (less than 0.3 pmol/l), but plasma cytochemical arginine vasopressin decreased from 0.96 +/- 0.14 to 0.07 +/- 0.02 pmol/l. There was a curvilinear relationship between plasma osmolality and plasma cytochemical arginine vasopressin, which militated against the concept of an osmotic threshold for vasopressin release.
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PMID:Development of a cytochemical assay for plasma vasopressin: application to studies on water loading normal man. 301 8


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