Idiopathic sudden sensorineural hearing loss(ISHL) is defined as an abrupt onset of sensorineural hearing loss without definite cause. The causes of sudden sensorineural hearing loss have not determined with precision until recently, but viral infections and vascular insufficiencies, such as vascular spasm, occlusion of sludging of erythrocytes were considered as major factors. The treatment has not been determined with precision until recently. But recently, as a effective regimen, diatrizoate meglumine(Hypaque) was introduced that fills the broken membrane pores and activated the sodium pump to restore the normal DC potential. The purpose of this study was to evaluate the effectiveness of a regimen for the treatment of the sudden sensorineural hearing loss with Hypaque, steroid and bed rest by retrospective review.
Bed Rest ; Diatrizoate* ; Erythrocytes ; Hearing ; Hearing Loss, Sensorineural* ; Membranes ; Retrospective Studies ; Sodium-Potassium-Exchanging ATPase ; Spasm

Hemiplegia ; diagnosis ; genetics ; Humans ; Mutation ; Prognosis ; Sodium-Potassium-Exchanging ATPase ; genetics

Epilepsy ; etiology ; Hemiplegia ; complications ; genetics ; Humans ; Infant ; Male ; Mutation ; Sodium-Potassium-Exchanging ATPase ; genetics

K(+) channels form a large family of membrane proteins that are expressed in a polarized fashion in any epithelial cell. Based on the transmembrane gradient for K(+) that is maintained by the Na(+)-K(+)-ATPase, these channels serve two principal functions for transepithelial transport: generation of membrane voltage and recycling of K(+). In this brief review, we will outline the importance of this ancient principle by examples of epithelial transport in the renal proximal tubule and gastric parietal cells. In both tissues, K(+) channel activity is rate-limiting for transport processes across the epithelial cells and essential for cell volume regulation. Recent experimental data using pharmacological tools and genetically modified animals have confirmed the original physiological concepts and specified the knowledge down to the molecular level. The development of highly active and tissue selective small molecule therapeutics has been impeded by two typical features of K(+) channels: their molecular architecture challenges the design of molecules with high affinity binding and they are expressed in a variety of tissues at the same time. Nevertheless, new insights into pathophysiology, e.g. that K(+) channel inhibition can block gastric acid secretion, render the clinical use of K(+) channel drugs in gastric disease and as kidney transport inhibitors highly attractive.
Animals ; Biological Transport ; Epithelial Cells ; physiology ; Kidney ; physiology ; Potassium ; Potassium Channels ; physiology ; Sodium-Potassium-Exchanging ATPase ; physiology

BACKGROUND: Metabolic dysfunctions characteristic of overt hypothyroidism (OH) start at the early stage of subclinical hypothyroidism (SCH). Na⁺/K⁺-ATPase (the sodium pump) is a transmembrane enzyme that plays a vital role in cellular activities in combination with membrane lipids. We evaluated the effects of early changes in thyroid hormone and membrane cholesterol on sodium pump activity in SCH and OH patients. METHODS: In 32 SCH patients, 35 OH patients, and 34 euthyroid patients, sodium pump activity and cholesterol levels in red blood cell membranes were measured. Serum thyroxine (T₄) and thyroid stimulating hormone (TSH) levels were measured using enzyme-linked immunosorbent assays. Differences in their mean values were analysed using post hoc analysis of variance. We assessed the dependence of the sodium pump on other metabolites by multiple regression analysis. RESULTS: Sodium pump activity and membrane cholesterol were lower in both hypothyroid groups than in control group, OH group exhibiting lower values than SCH group. In SCH group, sodium pump activity showed a significant direct dependence on membrane cholesterol with an inverse relationship with serum TSH levels. In OH group, sodium pump activity depended directly on membrane cholesterol and serum T4 levels. No dependence on serum cholesterol was observed in either case. CONCLUSION: Despite the presence of elevated serum cholesterol in hypothyroidism, membrane cholesterol contributed significantly to maintain sodium pump activity in the cells. A critical reduction in membrane cholesterol levels heralds compromised enzyme activity, even in the early stage of hypothyroidism, and this can be predicted by elevated TSH levels alone, without any evident clinical manifestations.
Cholesterol* ; Enzyme-Linked Immunosorbent Assay ; Erythrocytes ; Humans ; Hypothyroidism* ; Membrane Lipids ; Membranes* ; Sodium* ; Sodium-Potassium-Exchanging ATPase* ; Thyroid Gland ; Thyrotropin ; Thyroxine

An improved approach for determination of Na(+)-K(+)-ATPase activity in single proximal renal tubule of rat reported by Doucet and his colleagues has been suggested. The single proximal renal tubules were isolated by hand under stereomicroscope from collagenase II-treated renal cortical tissue in rats. The length of every single renal tubule segment obtained was measured. The single proximal renal tubules were treated with a hypoosmotic solution and with freeze-thaw successively, before incubation with [gamma-(32)P]-ATP. (32)Pi hydrolyzed from [gamma-(32)P]ATP by Na(+)-K(+)-ATPase in the single proximal renal tubules was assayed by liquid scintillation counting. The activity of Na(+)-K(+)-ATPase in the single proximal renal tubules was calculated by applying a modified formula. There was no significant difference in the measurement result of Na(+)-K(+)-ATPase activity between the method of Doucet et al. and the improved one, but the latter has advantage of less time, less reagents and being easy to operate.
Adenosine Triphosphate ; metabolism ; Animals ; Kidney Tubules, Proximal ; enzymology ; Male ; Microscopy ; Rats ; Rats, Wistar ; Sodium-Potassium-Exchanging ATPase ; metabolism ; Time Factors

The present study was designed to investigate the effect of administration of adrenomedullin (ADM) into subfornical organ (SFO) on renal tubular Na(+),K(+)-ATPase activity in rats. Rats under anesthesia were injected with ADM 0.1 mL (20 ng/mL) via an implanted cannula into SFO (n=6). Plasma ADM and serum endogenous digitalis-like factor (EDLF) levels were assayed with radioimmunoassay, and urine samples were collected via a canoula intubated in bladder. Urinary sodium concentration was assayed with flame spectrophotometry. Single proximal renal tubule segments were obtained by hand under stereomicroscope and its Na(+),K(+)-ATPase activity was measured by liquid scintillation counting. In addition, single proximal renal tubule segments from normal rats (n=6) were incubated with serum from animals administered with ADM into SFO, and then the Na(+),K(+)-ATPase activity was determined. The results showed that both urinary volume and sodium excretion amounted to the peak value at 30 min after ADM administration, and sustained a significant high level at 60 min (P<0.01). At 30 min after ADM administration, there was a significant increase in serum EDLF and a decrease in Na(+),K(+)-ATPase activity of proximal tubule (P<0.01, respectively), but not in plasma ADM level. Na(+),K(+)-ATPase activity was decreased significantly in single proximal renal tubule segments from normal rats incubated with serum from rats administered with ADM into SFO (P<0.01). These results suggest that the diuretic and natriuretic responses following administration of ADM into SFO are associated with the inhibition of renal tubule Na(+),K(+)-ATPase activity. The inhibition of renal tubule Na(+),K(+)-ATPase activity is related to the increase in the serum level of EDLF.
Adrenomedullin ; pharmacology ; Animals ; Kidney Tubules, Proximal ; drug effects ; enzymology ; Rats ; Sodium-Potassium-Exchanging ATPase ; metabolism ; Subfornical Organ

Animals ; Enzyme Inhibitors ; pharmacology ; Hepatitis ; immunology ; Immune Sera ; pharmacology ; Mice ; Sodium-Potassium-Exchanging ATPase ; antagonists & inhibitors ; metabolism

AIMTo study the effect of Na+, K(+)-ATPase inhibition by ouabain on growth and death of vascular endothelial cells ECV304 and involved mechanisms.

METHODSGrowth inhibition of ouabain on ECV304 cells was analyzed using MTT assay. The feature of cell death was studied by Hoechst 33342/PI staining, transmission electron microscopy and DNA agarose gel electrophoresis in ECV304 cells treated with ouabain. The mRNA expression of Na+, K(+)-ATPase alpha1, beta1-subunit was examined by reverse transcription PCR (RT-PCR).

RESULTSOuabain inhibited the growth of ECV304 cells in a dose and time-dependent manner. 10 micromol/L ouabain treated for 24 hours could stimulate the necrosis of ECV304 cells; When treated with 0.1 micromol/L ouabain for 24-48 hours, the cells showed obviously defluxion, the loss of cell-cell contacts, nuclear chromatin condensation, chromatin margination and DNA fragmentation. Na+, K(+)-ATPase alpha1-subunit mRNA expression was significantly up-regulated in ECV304 cells treated with ouabain while the beta1-subunit expression conversely showed a significant decrease.

CONCLUSIONOuabain could up-regulate Na+, K(+)-ATPase alpha1-Subunit expression and reduce beta1-Subunit expression which mediated signal transduction and decreased cell-cell adhesions and induced ECV304 cells death.

Cell Death ; drug effects ; Cell Line ; Endothelial Cells ; cytology ; drug effects ; metabolism ; Humans ; Ouabain ; pharmacology ; Sodium-Potassium-Exchanging ATPase ; metabolism

OBJECTIVETo explore the mechanism of cytotoxic effect of 2, 5-hexanedione (2, 5-HD) on motor neuron.

METHODSVsc4.1 (a cell line from motor neuron) was incubated with a series concentration of 2, 5-HD. The cell viability, Ca(2+) Mg(2+) ATPase and Na(+)K(+) ATPase were detected. Laser scanning confocal microscope (LSCM) was used for detecting intracellular calcium level. The average calcium level in VSC4.1 was measured by flow cytometry.

RESULTSThe cell viability was decreased when Vsc4.1 cells were treated with 2, 5-HD at the dosage of 2.5, 5.0, 7.5, 10, 15 and 20 mmol/L for 24 hours. Compared with the control group the activity of Ca(2+) Mg(2+) ATPase was decreased to 70.02%, 77.44% and 47.47% respectively; the activity of Na(+)K(+) ATPase was decreased to 82.07%, 72.45% and 50.71%. The difference was significant. Intracellular free calcium of VSC4.1 cell was increased rapidly within 10 s and then recovered within 40 seconds when it was exposed to 33.5 mmol/L 2, 5-HD. An increase in intracellular calcium was observed when the VSC4.1 was treated with 33.5 mmol/L 2, 5-HD. The peak of intracellular calcium level occurred ten minutes later.

CONCLUSIONThe disturbance of calcium homeostasis may be involved in the mechanisms of neurotoxicity of 2, 5-HD.

Animals ; Ca(2+) Mg(2+)-ATPase ; metabolism ; Calcium ; metabolism ; Cell Line ; Dose-Response Relationship, Drug ; Hexanones ; toxicity ; Motor Neurons ; drug effects ; metabolism ; Rats ; Sodium-Potassium-Exchanging ATPase ; metabolism