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)

To examine whether the adenosine triphosphatase (Na,K-ATPase) transport rate regulates transcellular NaCl reabsorption, experiments were performed on anesthetized volume-expanded dogs. Ouabain was injected into the renal artery in doses inhibiting 10 to 80% of the renal Na,K-ATPase activity. Acetazolamide was administered before ouabain to render the NaHCO3 reabsorption and associated NaCl reabsorption constant during variations in the glomerular filtration rate. Ouabain reduced sodium reabsorption significantly after inhibiting 20% of the Na,K-ATPase. By inhibiting 80% of the Na,K-ATPase, NaCl reabsorption was reduced by 40 to 50% without affecting NaHCO3 reabsorption. During mechanical constriction of the suprarenal aorta, the remaining NaCl reabsorption was constant until the glomerular filtration rate was lowered by about 50%. Bound ouabain and the remaining Na,K-ATPase activity were distributed between the cortex and medulla in proportion to the Na,K-ATPase activity before ouabain injection. The reduction in NaCl reabsorption and ouabain binding were correlated (r = 0.90), the slope suggesting a turnover for ATP similar to the in vitro turnover of 5700 ATP min-1 estimated from the relationship between the remaining Na,K-ATPase activity and bound ouabain (r = 0.95). We conclude that transcellular reabsorption of NaCl in the distal nephron reaches a maximum in volume-expanded dogs by saturating the sodium sites of Na,K-ATPase because even a small dose of ouabain inhibits NaCl reabsorption and because the calculated turnover for Na,K-ATPase activity is similar to in vitro maximum estimates. The Na,K-ATPase transport rate, therefore, limits transcellular NaCl reabsorption in volume-expanded dogs.
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PMID:Renal Na,K-adenosine triphosphatase transport rate limits transcellular NaCl reabsorption in distal nephrons of volume-expanded dogs. 301 21

Much evidence shows that glia regulates the cation and anion content of brain interstitial space. In rats the pH and bicarbonate (HCO3-) concentration of neurons and glia were derived from carbon 14-labeled HCO3- and dimethyloxazolidinedione uptake into brain and cerebrospinal fluid. Acetazolamide increases the total CO2 concentration in neurons and decreases the pH and HCO3- concentration in glia. Inhibition of glial carbonic anhydrase (CA) reduces conversion of neuronally derived CO2 to HCO3-, glial pH is lowered, and neuronal CO2 accumulates. CA therefore has an essential role in regulating pH in neurons, glia, and interstitial fluid. In audiogenic seizure mice, glial CA activity is increased and glial anion transport is reduced. As the mice age, seizure susceptibility, the increased CA activity, and the defect in anion transport disappear concurrently. The enhanced CA activity in the glial cells of these mice is an adaptive mechanism to overcome the defect in anion transport that results from a deficiency of HCO3- -dependent and Na+- and K+ -dependent adenosine triphosphatase. Pentylenetetrazol stimulates neurons in neonatal rats, but after 10 days of age, when glia is present, it too is stimulated and the seizures are attenuated. Cobalt implantation in the cortex of rats also induces a glial response that ameliorates the focal seizures produced by this procedure.
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PMID:Ionic and acid-base regulation of neurons and glia during seizures. 615 Jun 82