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)

Bumetanide, a sulfamyl-aminobenzoic acid derivative, is a new and highly effective diuretic agent. The present studies were designed to examine its effects on cation transport in human red cells. At a concentration of 10(-3) M, the drug inhibited both active and passive unidirectional sodium fluxes, as well as active potassium influx. It also caused a significant inhibition of glycolysis. The inhibition caused by bumetanide was less than that seen with ouabain alone, but a bumetanide effect was also present in ouabain-treated cells. Bumetanide had no effect on red cell Na-K adenosine triphosphatase activity and did not affect net transport of sodium in sodium-loaded cells. The data are consistent with a model in which the inhibition of monovalent cation movement in red cells by bumetanide is related to an effect of this compound in decreasing the permeability of the red cell membrane to sodium.
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PMID:The effect of bumetanide on cation transport in human red blood cells. 14 26

Cation-transport properties were compared in a human leukemic cell line (K562) and its vincristine-selected, mdr1-gene-expressing sublines (K562/Vcr30 and K562/Vcr150) by the capacity of the cells to accumulate the potassium analogue thallium (201Tl). Determination of the time course of thallium accumulation in the absence and presence of ouabain, an inhibitor of sodium-potassium adenosine triphosphatase (ATPase), showed that the initial (at 20 min) rate of ouabain-resistant uptake was about 70% higher in the K562/Vcr30 cells than in the parental line. The maximal rate (Vmax) of ouabain-resistant uptake was 78 mmol/h for K562 cells and 115 mmol/h for K562/Vcr30 cells, and the Michaelis constant (Km) was 0.37 and 0.18 mmol, respectively. Bumetanide (50 microM), a specific inhibitor of ouabain-resistant Na-K-Cl cotransport, inhibited the elevated 201Tl uptake in K562/Vcr150 cells but had no effect on cellular vincristine accumulation. Incubation with different multidrug resistance (MDR)-reversing agents (verapamil as well as cyclosporin A and its analogue PSC833) had no significant effect on 201Tl uptake. Membrane depolarization by an elevation of the potassium concentration in the incubation medium did not affect vincristine accumulation in any cell line, which indicated that the changed drug-transport properties in mdr1-gene-expressing cells were not due to membrane hyperpolarization. It was concluded that P-glycoprotein-positive cells have a more efficient ouabain-resistant cation-transport mechanism than to cells without P-glycoprotein. A functional relationship between this phenomenon and MDR was not identified.
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PMID:Increased cation transport in mdr1-gene-expressing K562 cells. 772 Jan 83

Ion transport by the airway epithelium contributes to the regulation of the quantity and composition of respiratory tract fluid, thereby affecting mucociliary clearance. We have investigated the effect of the mucoactive drug S-carboxymethylcysteine-lysine salt (S-CMC-Lys) on the transepithelial bioelectric properties of isolated rabbit trachea. Transepithelial potential difference (Vms), short-circuit current (Isc) and resistance (R) were measured in the isolated rabbit trachea mounted between flux half-chambers, in the presence and in the absence of S-CMC-Lys (100 microM), added to the mucosal or submucosal chamber. In some experiments, tissues were also exposed to ion channel-inhibitors, in order to evaluate the contribution of Na+ and Cl- active transport to Isc. The excised rabbit trachea expressed transepithelial bioelectric properties based on an active ion transport supported by the Na(+)-K(+)-adenosine triphosphatase (ATPase) activity, since ouabain (500 microM) completely abolished the transepithelial potential difference. In control preparations, Vms and Isc declined significantly during 300 min recording, whereas R remained constant. The Isc decline was essentially attributable to a decrease in Cl- transport. Bumetanide (100 microM) almost completely abolished the Isc fraction related to Cl- transport. Treatment of the tissues with S-CMC-Lys reduced the progressive fall in Isc, with the most clear-cut and significant effect observed for the mucosal treatment. In parallel, S-CMC-Lys significantly lowered R, without affecting Vms. Either mucosal or submucosal exposure to S-CMC-Lys significantly increased Cl- secretion to normal values, whilst Na+ absorption was not modified.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Stimulation of Cl- secretion by the mucoactive drug S-carboxymethylcysteine-lysine salt in the isolated rabbit trachea. 799 91