Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P20020 (adenosine triphosphatase)
 3,299 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In order to define a physiological role for circulating inhibitors of sodium, potassium-dependent adenosine triphosphatase (Na+,K+-ATPase), plasma was obtained from control, water deplete, water repleted, sodium deplete and sodium loaded rats. The effect of this plasma on Na+,K+-ATPase activity, and its transport equivalent 86Rb uptake, was measured in separated guinea pig renal cortical tubules. Plasma from water deplete rats had a raised plasma osmolality and sodium concentration and a significant inhibitory effect on Na+,K+-ATPase (14%) and 86Rb uptake (24%) compared with control or water repleted rats. Inhibition of Na+,K+-ATPase and 86Rb transport was not seen with plasma from rats after dietary sodium loading (urine sodium 5.2 +/- 0.9 mmol/day) compared with low sodium diet controls (urine sodium 0.41 +/- 0.08 mmol/day). Des-amino arginine vasopressin in vivo produced no inhibition of Na+,K+-ATPase or Rb transport. These studies suggest, that in terms of common homoeostatic insults, circulating inhibitors of Na+,K+-ATPase are more responsive to water depletion than to oral sodium loading. The inhibitors may fulfil a physiological role in increasing sodium excretion to maintain osmolality after dehydration.
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PMID:Water depletion, not oral sodium loading, increases levels of sodium, potassium-dependent adenosine triphosphatase inhibitors in rat plasma. 303 56

Endogenous enzyme activity can be readily and routinely demonstrated in ultrathin, frozen sections for electron microscopy. The procedure employed to obtain the best structural preservation as well as enzyme activity in thin sections involved fixation in glutaraldehyde, embedding in thiolated gelatin or pure gelatin, partial dehydration in glycerol, and sectioning in a cryostat at -35 degrees C with a slightly modified Porter-Blum microtome on which the tissue is maintained at -70 degrees C and the knife at -23 degrees C. Kidney cortex was used as test tissue, but a few other organs were occasionally used. Thin sections were floated on the surface of several incubation media routinely employed for enzyme cytochemistry. Positive, specific reactions were obtained for alkaline phosphatase in kidney brush border, for adenosine triphosphatase in brush border and in basal membranes of distal tubules, for acid phosphatase and esterase in lysosomes, and for NADH diaphorase in mitochondria. Mitochondrial ATPase was sporadically evident only in the distal tubule of the kidney. Localizations of enzyme activity reported by other technical approaches were confirmed and in some cases somewhat improved.
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PMID:Ultrathin frozen sections. II. Demonstration of enzymic activity. 429 6

No specific inhibitors of the plasma membrane Ca(2+) pump have been found to date, limiting research on the particular contribution of this pump to the Ca(2+) homeostasis of animal cells. The search for Ca(2+) pump inhibitors may have been hampered by the lack of an efficient screening method to measure pump activity that would provide an alternative to the lengthy and costly adenosine triphosphatase or Ca(2+)-flux measurements. We propose here a novel screening method in which Ca(2+) pump inhibition is translated into easily measurable cell dehydration. Intact human red cells, suspended in Ca(2+)-containing, low-K(+) buffers were exposed to sequential additions of (1) ionophore A23187 (t = 0) to load the cells with Ca(2+); (2) CoCl(2) (t = 1 minute) to block ionophore-mediated Ca(2+) transport and to allow complete extrusion of the Ca(2+) load by the pump in less than 5 minutes; and (3) NaSCN (t = 6 minutes) to accelerate cell dehydration via Ca(2+)-sensitive K(+) channels when the Ca(2+) load is retained as a result of Ca(2+) pump inhibition. Samples were taken at 10 to 25 minutes after ionophore addition and delivered into hypotonic media containing about 45 mmol/L NaCl. Non-dehydrated cells-with normal, uninhibited pumps-instantly underwent lysis, whereas dehydrated cells-with inhibited pumps-resisted lysis, resulting in translucent or opaque samples, respectively, which were quantifiable by light-absorption measurements. Vanadate was used as a test substance to assess the effect of putative pump inhibitors. This method offers a cost-efficient and easily automated alternative for testing large numbers of natural or synthetic agents.
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PMID:A fast and simple screening test to search for specific inhibitors of the plasma membrane calcium pump. 1124 Oct 30