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)

1. Explants of mammary tissue from pseudopregnant rabbits were cultured at 37 degrees C in air for 24-48h in Medium 199 buffered with 20mm-Hepes [4-(2-hydroxyethyl)-1-piperazine-ethanesulphonic acid]. The medium contained insulin and corticosterone, or insulin, corticosterone and sheep prolactin in the presence or absence of ouabain, an inhibitor of Na(+)/K(+)-dependent adenosine triphosphatase. The responses of explants were assessed histologically, by measuring the tissue concentration of K(+), and by rates of synthesis of RNA, protein and fatty acids. The effect of ouabain on Na(+) and K(+) concentrations in slices of lactating rabbit mammary-gland tissue incubated for 1h at 37 degrees C in Krebs bicarbonate buffer was also studied. 2. Prolactin increased the concentration of K(+) in mammary explants, an effect prevented by ouabain. In slices of lactating tissue, there was a linear relationship between the log dose of ouabain (from 0.1 to 10mum) and increased Na(+) and decreased K(+) concentrations in the tissue. 3. Ouabain at concentrations up to 1mum did not affect the rate of synthesis of RNA, protein or fatty acids by explants cultured with insulin and corticosterone. By contrast, the stimulatory effect of prolactin on protein synthesis was diminished and the induction of medium-chain fatty acid synthesis by prolactin was almost abolished. RNA synthesis was unaffected. Histological examination showed no tissue damage by 1mum-ouabain. 4. Explants cultured in the presence of 2mum-ouabain for 24h retained their ability to respond to prolactin when the ouabain was removed from the culture medium. Between 24 and 48h they showed responses to prolactin of a magnitude similar to those of explants never exposed to ouabain. 5. These results show that a fully functional Na(+)/K(+)-dependent adenosine triphosphatase system is necessary for prolactin to promote secretory activity in rabbit mammary gland.
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PMID:Inhibition by low concentrations of ouabain of prolactin-induced lactogenesis in rabbit mammary-gland explants. 56 78

Sodium bicarbonate (NaHCO3) is the principal salt in coal bed natural gas produced water from the Powder River Structural Basin, Wyoming, USA, and concentrations of up to 3000 mg NaHCO3/L have been documented at some locations. No adequate studies have been performed to assess the chronic effects of NaHCO3 exposure. The present study was initiated to investigate the chronic toxicity and define sublethal effects at the individual organism level to explain the mechanisms of NaHCO3 toxicity. Three chronic experiments were completed with fathead minnows (Pimephales promelas), 1 with white suckers (Catostomus commersoni), 1 with Ceriodaphnia dubia, and 1 with a freshwater mussel, (Lampsilis siliquoidea). The data demonstrated that approximately 500 mg NaHCO3/L to 1000 mg NaHCO3/L affected all species of experimental aquatic animals in chronic exposure conditions. Freshwater mussels were the least sensitive to NaHCO3 exposure, with a 10-d inhibition concentration that affects 20% of the sample population (IC20) of 952 mg NaHCO3/L. The IC20 for C. dubia was the smallest, at 359 mg NaHCO3/L. A significant decrease in sodium-potassium adenosine triphosphatase (Na(+)/K(+) ATPase) together with the lack of growth effects suggests that Na(+)/K(+) ATPase activity was shut down before the onset of death. Several histological anomalies, including increased incidence of necrotic cells, suggested that fish were adversely affected as a result of exposure to >450 mg NaHCO3/L. This article is a US Government work and is in the public domain in the USA.
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PMID:The chronic toxicity of sodium bicarbonate, a major component of coal bed natural gas produced waters. 2450 36