No abstract available.
Ion Transport* ; Translational Medical Research*

All urate transport occurs across the renal epithelial cells of the proximal tubule. Most of the filtered urate is reabsorbed in the S1 segment of the early proximal tubule. This is followed by tubular secretion in the S2 segment of the proximal tubule and approximately 50% of the filtered urate flows back into the tubular lumen. Most of the secreted urate undergoes postsecretory reabsorption that occurs predominantly in the last S3 segment of the proximal tubule. Recently, four proteins that transport urate have been identified at the molecular level. These proteins are an electrogenic urate uniporter, urate transporter/channel (UAT), two members of the organic anion transporter (OAT) family, OAT1 and OAT3, and a protein with some homology to OAT4, designated URAT1.
Epithelial Cells ; Humans ; Ion Transport ; Uric Acid*

Ion channels and transporters represent two major types of pathways of transmembrane transport for ions. Distinct from ion channels which conduct passive ionic diffusion, ion transporters mediate active transport of ions. In the perspective of biochemistry, ion transporters are enzymes that catalyze the movement of ions across the plasma membrane. In the present review, we selected the Na(+)/HCO3(-) cotransporter (NBC) as an example to analyze the key biochemical and biophysical properties of ion transporters, including stoichiometry, turnover number and transport capacity. Moreover, we provided an analysis of the electrophysiological principles of NBC based on the laws of thermodynamics. Based on the thermodynamical analysis, we showed how the stoichiometry of an NBC determines the direction of its ion transport. Finally, we reviewed the methodology for experimental determination of the stoichiometry of NBC, as well as the physiological significance of the stoichiometry of NBCs in specific tissues.
Electrophysiological Phenomena ; Ion Transport ; Sodium-Bicarbonate Symporters

PURPOSE: To evaluate the differences of radiological outcomes of uniportal and biportal vertebroplasty in the point of bone cement distribution and leakage. MATERIALS AND METHODS: A retrospective study reviewing the period between May 2002 and January 2006 investigated 100 vertebrae which underwent vertebroplasty and followed for more than three months by uniportal approach (55 vertebrae, group 1) and biportal approach (45 vertebrae, group 2). The operative time, the amount of bone cement injected, anterior vertebral height restoration, kyphotic angle, bone cement distribution, and bone cement leakage were evaluated. RESULTS: The amount of injected bone cement of group 1 (3.9 cc) was statistically smaller than that of group 2 (5.1 cc) (p=0.016). There were no significant differences in the operative time, anterior vertebral height restoration, kyphotic angle in both groups. The rate of bone cement distribution over 8 zones was significantly higher in group 2 than in group 1 (p=0.014). However, the rate of bone cement distribution over 7 zones and the rate of bone cement distributed on whole anterior vertebral body were not significantly different in both groups. The cement leakage was not also significantly different in both groups. CONCLUSION: Although the amount of injected bone cement was smaller in uniportal vertebroplasty, the radiological results and cement leakage were similar to biportal vertebroplasty. These findings suggest that uniportal vertebroplasty can be the operative options in osteoporotic vertebral fracture.
Ion Transport* ; Operative Time ; Retrospective Studies ; Spine ; Vertebroplasty*

No abstract available.
Breast Neoplasms* ; Breast* ; Ion Transport* ; Sodium Iodide* ; Sodium*

No abstract available.
Breast Neoplasms* ; Breast* ; Ion Transport* ; Sodium Iodide* ; Sodium*

This study was undertaken to examine the effect of ethanol on Na+-dependent transport systems (glucose, phosphate, and dicarboxylate) in renal brush-border membrane vesicles (BBMV). Ethanol inhibited Na+-dependent uptakes of glucose, phosphate, and succinate in a dose-dependent manner, but not the uptakes of Na+-independent. The H+/TEA antiport was reduced by 8% ethanol. Kinetic analysis showed that ethanol caused a decrease in Vmax of three transport systems, leaving Km values unchanged. Ethanol decreased phlorizin binding, which was closely correlated with the decrease in Vmax of Na+-glucose uptake. These results indicate that ethanol inhibits Na+-dependent uptakes of glucose, phosphate, and dicaboxylate and that the reduction in Vmax of Na+-glucose uptake is caused by a decrease in the number of active carrier proteins in the membrane.
Carrier Proteins ; Ethanol* ; Glucose ; Ion Transport ; Membranes* ; Phlorhizin ; Succinic Acid

Iodide uptake across the membranes of thyroid follicular cells and cancer cells occurs through an active transport process mediated by the sodium-iodide symporter (NIS). The rat and human NIS-coding genes were cloned and identified in 1996. Evaluation of NIS gene and protein expression is critical for the management of thyroid cancer, and several approaches to increase NIS levels have been tried. Identification of the NIS gene has provided a means of expanding its role in radionuclide therapy and molecular target-specific theragnosis (therapy and diagnosis using the same molecular target). In this article, we describe the relationship between NIS expression and the thyroid carcinoma treatment using I-131 and alternative therapeutic approaches.
Animals ; Biological Transport, Active ; Clone Cells ; Diagnosis ; Humans ; Ion Transport ; Membranes ; Rats ; Thyroid Gland ; Thyroid Neoplasms*

BACKGROUND AND OBJECTIVES: Rhinovirus infection on the airway epithelial cells results in derangement in mucociliary clearance. However, the contribution of altered ion transport across the epithelial cells in rhinovirus-induced alteration in mucociliary clearance has not been studied yet. Thus, we aimed to investigate the effect of rhinovirus infection on the electrical property of airway epithelial cells. MATERIALS AND METHODS: Tracheal mucosae were harvested and digested with protease. The epithelial cells thus obtained were cultured in air-liquid interface method. Rhinvovirus-16s were infected for 1 hour on the epithelial cells and cultured for 48 hours thereafter. Transepithelial resistance was measured by a chopstick voltmeter and short circuit current was measured by Ussing chamber technique. The electrical properties of control and infection groups were compared. RESULTS: The change in the transepithelial resistance in the control group was 240 ohm.cm2, while it was 263 ohm.cm2 in the RV infected epithelium. The baseline short circuit current was 6.3 microEq.cm-2.h-1 in the control group and 7.2 microEq.cm-2.h-1 in the RV infected group. The difference was not significant. Change in short circuit current induced by mucosally applied amiloride and foskolin were not different significantly in both groups. CONCLUSION: The results of this study indicated that rhinovirus infection in the airway epithelial cells does not affect the electrical property, which reflects the function of ion channels in the epithelial cells.
Amiloride ; Epithelial Cells* ; Epithelium ; Ion Channels ; Ion Transport ; Mucociliary Clearance ; Mucous Membrane ; Rhinovirus

Intracellular pH regulation of osteoblasts is of a great importance in the process of bone formation and resorption, and has been suggested to be mediated via intracellular Ca2+ and cAMP messenger systems. To elucidate the mechanism of modulation of intracellular pH by parathyroid hormone and PMA(Phorbo1-12-myristate-13-acetate), effects of these agonists on the individual transporter system, Na+-H+ antiporter and Cl−-HCO3-(−OH−) exchanger, were investigated. Intracellular pH and Ca2+ were measured by using the fluorescent dye BCECF and fura-2, respectively, in UMR-106 cell monolayer grown on glass coverslip. Addition of tumor promotor, PMA(luM) caused 0.14 unit pH rise of resting intracellular pH(pHi) and 38% increase of the initial rate of pHi recovery after cytosolic acid load. Perfusion of Cl−-free solution resulted in rapid cytosolic alkalinization of which the rate was increased 26% by preincubation of PMA. Ca2+ ionophore, ionomycin (1uM) decreased resting pHi by 0.17 unit, but had no effect on the initial rate of pHi recovery after cytosolic acid load. However, the addition of ionomycin augmented the initial rate of pHi increase after Cl−-depletion outside the cells by 34% over the control. Stimulation of cells with parathyroid hormone(10-8M) caused an initial acidification (0.27 unit) followed by cytosolic alkalinization, with inhibiting effect on the initial rate of pHi recovery after acid load (42%). But parathyroid hormone did not have any significant effect on the rate of pHi increase after Cl−-depletion. PMA caused a sustained increase of intracellular Ca2+, of which the peak depended on the concentration of Ca2+ in extracellular medium. Ionomycin caused a transient increase of Ca2+ but PTH had no significant increase of intracellular Ca2+ in the concentration range of 10-6M to 10-12M tested. 10-8M PTH increased cAMP levels by about 10-fold and 10-10M PTH did by 1.6-fold. PMA, which increased cytosolic Ca2+ concentration, also had an stimulatory effect on cAMP production in the concentration range of 10-5M to 10-6M by 2-fold. These findings suggest that in UMR-106 cells Ca2+ and cAMP can influence pHi by altering the activity of pHi regulatory transporter system, and parathyroid hormones modulate pHi by inhibiting Na+-H+ antiporter via intracellular increase of cAMP, which is probably accounts for the inhibitory effect of parathyroid hormone on the proliferation of osteoblasts.
Cytosol ; Fura-2 ; Glass ; Hydrogen-Ion Concentration ; Ion Transport ; Ionomycin ; Osteoblasts ; Osteogenesis ; Parathyroid Hormone ; Perfusion