influence of folic acid on the cns is still unclear. folate has a neuroprotective effect, while on the other hand excess folate can exacerbate seizures in epileptics. the aim of the present study was to examine the effect of subchronic administration of folic acid on behavioural and electroencephalographic (eeg) characteristics of dl homocysteine thiolactone induced seizures in adult rats. t...

Previous studies in kidney, heart, and liver cells have demonstrated that dexamethasone regulates the expression of Na-K-ATPase. In the lungs, Na-K-ATPase has been reported in alveolar epithelial type II (ATII) cells and is thought to participate in active Na+ transport and lung edema clearance. The aim of this study was to determine whether Na-K-ATPase would be regulated by dexamethasone in cu...

Most vital cellular functions are dependent on a fine-tuned regulation of intracellular ion homeostasis. Here we have demonstrated, using COS cells that were untransfected or transfected with wild-type rat ouabain-resistant Na(+)-K(+)-ATPase, that partial inhibition of Na(+)-K(+)-ATPase has a dramatic influence on cell attachment to fibronectin. Ouabain dose-dependently decreased attachment in ...

The content and distribution of the membrane-bound enzyme (Na+ + K+)-ATPase in a rat cerebral C6 glioma was determined by immunocytochemistry, immunoblots and enzyme assay. In the C6 glioma cell culture (Na+ + K+)-ATPase activity was about 20% of (Mg2+ + Na+ + K+)-ATPase activity. However, (Mg2+ + Na+ + K+)-ATPase activity in the cerebral C6 gliomas was very close to Mg2+ baseline and not signi...

OBJECTIVE Degeneration of chronically demyelinated axons is a major cause of irreversible neurological decline in the human central nervous system disease, multiple sclerosis (MS). Although the molecular mechanisms responsible for this axonal degeneration remain to be elucidated, dysfunction of axonal Na+/K+ ATPase is thought to be central. To date, however, the distribution of Na+/K+ ATPase ha...

The alveolar epithelium is composed of alveolar type 1 (AT1) and alveolar type 2 (AT2) cells, which represent 95% and 5% of the alveolar surface area, respectively. Lung liquid clearance is driven by the osmotic gradient generated by the Na,K-ATPase. AT2 cells have been shown to express the 1 Na,K-ATPase. We postulated that AT1 cells, because of their larger surface area, should be important in...

Diminished (Na,K)-ATPase activity in diabetic peripheral nerve is attributed to an underlying depletion of free myo-inositol, but no biochemical mechanism linking myo-inositol metabolism and (Na,K)-ATPase has emerged. Since inositol phospholipid turnover releases inositol-(1,4,5)-tris-phosphate and diacylglycerol, two putative "second messengers" that modulate protein kinase C, the effect of pr...

Phosphorylation of purified Na+,K(+)-ATPase by cAMP-dependent protein kinase (protein kinase A) decreases the activity of this enzyme. We have now shown, using several experimental approaches, that a highly conserved seryl residue on the catalytic (alpha) subunit of Na+,K(+)-ATPase, corresponding to Ser943 of the rat alpha 1 isoform, is the phosphorylation site for protein kinase A. cDNAs corre...

Na,K-ATPase is a key enzyme that regulates a variety of transport functions in epithelial cells. In this study, we demonstrate a role for Na,K-ATPase in the formation of tight junctions, desmosomes, and epithelial polarity with the use of the calcium switch model in Madin-Darby canine kidney cells. Inhibition of Na,K-ATPase either by ouabain or potassium depletion prevented the formation of tig...

BACKGROUND P2Y receptor activation may link the effect of purines to increased maximal in vitro activity of the Na,K-ATPase in rat muscle. The hypothesis that a similar mechanism is present in human skeletal muscle was investigated with membranes from rat and human skeletal muscle. RESULTS Membranes purified from rat and human muscles were used in the Na,K-ATPase assay. Incubation with ADP, t...