Changes In Chloride Concentration Research Articles

Sodium Chloride Affects Helicobacter pylori Growth and Gene Expression

Epidemiological evidence links high-salt diets and Helicobacter pylori infection with increased risk of developing gastric maladies. The mechanism by which elevated sodium chloride content causes these manifestations is unclear. Here we characterize the response of H. pylori to temporal changes in sodium chloride concentration and show that growth, cell morphology, survival, and virulence factor expression are all altered by increased salt concentration.

Time resolved secretion of chloride from a monolayer of mucin-secreting epithelial cells

Short-circuit current (Isc) measurement is used to quantify transepithelial ion flux. This technique provides a direct measure of net charge transport across a cell monolayer. Isc however, lacks chemical selectivity. Chemically resolved ion fluxes may be much greater than Isc, and differ in different biological processes. This work describes a novel experimental approach and deconvolution method to obtain temporally resolved ion fluxes at epithelial cell monolayers. HT29-Cl.16E cells, a sub clone of the human colonic cancer cell line HT29 was used as a model cell line to validate this approach in the context of epithelial transport studies. This cell line is known to secrete chloride in response to purinergic stimulation. Changes in chloride concentration after stimulation with 1 mM ATP plus 50 nM phorbol-myristate acetate (PMA) are recorded with a chloride ion-selective electrode (ISE) at a short distance (approximately 50 microm) from the monolayer. The recorded concentrations are transformed to corresponding chloride flux across the monolayer using a deconvolution algorithm for extracellular mass transport based on minimization of the shape error function (Nair and Gratzl in Anal Chem 77:2875-2888, 2005). Simultaneous voltage clamp yields the associated net electrical charge flux (Isc). The dynamics of Cl(-) flux did correlate with that of the electrical flux, but was found to be greater in amplitude. This suggests that Cl(-) may not be the only ion secreted. The method of simultaneously assessing ionic and electrical fluxes with a temporal resolution of seconds provides unique information about the dynamics of solute fluxes across the apical membrane.

A rapid method for determining apparent diffusion coefficients in Chalk and other consolidated porous media

The development of a method for the determination of the apparent diffusion coefficient, DA, for chloride in saturated Chalk cores is described. The method is rapid compared with other approaches, taking typically less than 24 h for a single determination. Cylindrical Chalk cores approximately 25 mm high by 25 mm in diameter, which are routinely used in porosity and permeability measurements and which had been pre-equilibrated with a 200 mg/L chloride solution, were sealed at both ends and attached to a slowly rotating spindle suspended in a reservoir. A chloride ion-selective electrode (ISE) connected to a data logger was used to record chloride diffusion out of the core. DA was estimated by analysing the change in chloride concentration in the reservoir with time. Diffusion coefficients were estimated for six Chalk samples from a range of Chalk lithologies. Sample porosities for these Chalks ranged from 32% to 48% and gas permeabilities from 0.3 to 8.2 × 10?9 m2. The DA was found to vary from 3.1 to 8.7 × 10?10 m2/s, a similar range to that observed by others. A bromide ISE was also used on one sample and found to give a similar DA to that obtained for chloride. This approach, which combines a rigorous mathematical model of diffusion with a relatively simple practical method, could easily be adapted for other ions and for other consolidated porous media.

Altered chloride homeostasis in neurological disorders: a new target

Other than modifying either neurotransmitter release or receptor expression and/or properties, one way to modulate gamma-aminobutyric acid (GABA)A and glycine receptor-mediated signalling is to alter the transmembrane gradient for chloride ions. Because intracellular chloride concentration is low in neurons, and the reversal potential for chloride currents is close to the resting membrane potential, small changes in intracellular chloride concentration can dramatically affect the strength and even polarity of GABA/glycine-mediated transmission. It now appears that chloride homeostasis is actively regulated in the adult brain and affected by endogenous neuromodulators such as brain-derived neurotrophic factor. Modulating chloride gradients even emerges as a mechanism by which microglia can control neuronal excitability. These findings, together with the observation of altered chloride homeostasis in several neurological disorders, point to new targets for therapeutic agents.

The Na+:Cl– Cotransporter Is Activated and Phosphorylated at the Amino-terminal Domain upon Intracellular Chloride Depletion

The renal Na(+):Cl(-) cotransporter rNCC is mutated in human disease, is the therapeutic target of thiazide-type diuretics, and is clearly involved in arterial blood pressure regulation. rNCC belongs to an electroneutral cation-coupled chloride cotransporter family (SLC12A) that has two major branches with inverse physiological functions and regulation: sodium-driven cotransporters (NCC and NKCC1/2) that mediate cellular Cl(-) influx are activated by phosphorylation, whereas potassium-driven cotransporters (KCCs) that mediate cellular Cl(-) efflux are activated by dephosphorylation. A cluster of three threonine residues at the amino-terminal domain has been implicated in the regulation of NKCC1/2 by intracellular chloride, cell volume, vasopressin, and WNK/STE-20 kinases. Nothing is known, however, about rNCC regulatory mechanisms. By using rNCC heterologous expression in Xenopus laevis oocytes, here we show that two independent intracellular chloride-depleting strategies increased rNCC activity by 3-fold. The effect of both strategies was synergistic and dose-dependent. Confocal microscopy of enhanced green fluorescent protein-tagged rNCC showed no changes in rNCC cell surface expression, whereas immunoblot analysis, using the R5-anti-NKCC1-phosphoantibody, revealed increased phosphorylation of rNCC amino-terminal domain threonine residues Thr(53) and Thr(58). Elimination of these threonines together with serine residue Ser(71) completely prevented rNCC response to intracellular chloride depletion. We conclude that rNCC is activated by a mechanism that involves amino-terminal domain phosphorylation.

Estimation of groundwater recharge from water storage structures in a semi-arid climate of India

Groundwater recharge from water storage structures under semi-arid conditions of western India has been estimated by employing water table fluctuation (WTF) and chloride mass balance (CMB) methods. Groundwater recharge was estimated as 7.3% and 9.7% of the annual rainfall by WTF method for the years 2003 and 2004, respectively while the two years average recharge was estimated as 7.5% using CMB method. A Recharge function depicting the relationship between potential recharge from storage structures and successive day averaged storage depths was better exhibited by a power function. A diagnostic relationship correlating the rainfall to the potential recharge from water storage structures has been developed to explain the characteristics of the storage structures for a given geographical location. The study has revealed that a minimum of 104.3 mm cumulative rainfall is required to generate 1 mm of recharge from the water storage structures. It was also inferred that the storage structures have limited capacity to induce maximum recharge irrespective of the amount of rainfall and maximum recharge to rainfall ratio is achieved at a lower rainfall than the average annual rainfall of the area. An empirical linear relationship was found to reasonably correlate the changes in chloride concentration with water table rise or fall in the study area.

Regulation of KCC2 and NKCC during development: Membrane insertion and differences between cell types

The developmental switch of GABA's action from excitation to inhibition is likely due to a change in intracellular chloride concentration from high to low. Here we determined if the GABA switch correlates with the developmental expression patterns of KCC2, the chloride extruder K+-Cl- cotransporter, and NKCC, the chloride accumulator Na+-K+-Cl- cotransporter. Immunoblots of ferret retina showed that KCC2 upregulated in an exponential manner similar to synaptophysin (a synaptic marker). In contrast, NKCC, which was initially expressed at a constant level, upregulated quickly between P14 and P28, and finally downregulated to an adult level that was greater than the initial phase. At the cellular level, immunocytochemistry showed that in the inner plexiform layer KCC2's density increased gradually and its localization within ganglion cells shifted from being primarily in the cytosol (between P1-13) to being in the plasma membrane (after P21). In the outer plexiform layer, KCC2 was detected as soon as this layer started to form and increased gradually. Interestingly, however, KCC2 was initially restricted to photoreceptor terminals, while in the adult it was restricted to bipolar dendrites. Thus, the overall KCC2 expression level in ferret retina increases with age, but the time course differs between cell types. In ganglion cells the upregulation of KCC2 by itself cannot explain the relatively fast switch in GABA's action; additional events, possibly KCC2's integration into the plasma membrane and downregulation of NKCC, might also contribute. In photoreceptors the transient expression of KCC2 suggests a role for this transporter in development.

Use of sodium concentration and anion gap to improve correlation between serum chloride and bicarbonate concentrations

Although most acid-base disorders cause opposite and equal changes in serum chloride and bicarbonate concentrations, this inverse relationship can be distorted by changes in the anion gap and/or water balance. Therefore, we examined the relationship between chloride and bicarbonate before and after adjusting for anion gap and serum sodium concentration. Patients with abnormal electrolytes were grouped by chloride and bicarbonate concentrations (low, normal, and high). Then, chloride and anion gap-adjusted bicarbonate were adjusted for water excess (or deficit), manifesting as hyponatremia (or hypernatremia), after which patients were reclassified. Classification by chloride and bicarbonate changed in 82% of the 135 patients after adjustment for anion gap and sodium. Serum chloride and bicarbonate were each low (concordant) in 23 patients, while 18 had discordant chlorides and bicarbonates (9 low/high, 9 high/low). After adjustments, chloride and bicarbonate were discordant in 40 patients (31 low/high, 9 high/low) and concordant in none. The correlation between serum chloride and bicarbonate improved from -0.459 to -0.998 after adjustments for sodium and anion gap. A very close inverse relationship between serum chloride and bicarbonate concentrations is commonly distorted by concomitant water disturbances and anion gap acidoses in internal medicine patients admitted with electrolyte disorders.

Change in intracellular chloride concentration caused by regulatory volume decrease is the primary hypotonic signal in renal epithelial A6 cells

Change in intracellular chloride concentration caused by regulatory volume decrease is the primary hypotonic signal in renal epithelial A6 cells

Chloride concentration affects Kv channel voltage-gating kinetics: Importance of experimental anion concentrations

Chloride concentration has been shown to have a dramatic impact on protein folding and subsequent tertiary conformation [K.D. Collins, Ions from the Hofmeister series and osmolytes: effects on proteins in solution and in the crystallization process, Methods 34 (2004) 300–311; I. Jelesarov, E. Durr, R.M. Thomas, H.R. Bosshard, Salt effects on hydrophobic interaction and charge screening in the folding of a negatively charged peptide to a coiled coil (leucine zipper), Biochemistry 37 (1998) 7539–7550]. As it is known that Kv channel gating is linked to the stability of the cytoplasmic T1 multimerization domain conformation [D.L. Minor, Y.F. Lin, B.C. Mobley, A. Avelar, Y.N. Jan, L.Y. Jan, J.M. Berger, The polar T1 interface is linked to conformational changes that open the voltage-gated potassium channel, Cell 102 (2000) 657–670; B.A. Yi, D.L. Minor Jr., Y.F. Lin, Y.N. Jan, L.Y. Jan, Controlling potassium channel activities: interplay between the membrane and intracellular factors, Proc. Natl. Acad. Sci. U.S.A. 98 (2001) 11016–11023] and that intracellular chloride concentration has been linked to Kv channel kinetics [L.K. Bekar, W. Walz, Intracellular chloride modulates A-type potassium currents in astrocytes, Glia 39 (2002) 207–216; W.B. Thoreson, S.L. Stella, Anion modulation of calcium current voltage dependence and amplitude in salamander rods, Biochim. Biophys. Acta 1464 (2000) 142–150], the objective of the present study was to address how chloride concentration changes affect Kv channel kinetics more closely in an isolated expression system. Initially, no significant chloride concentration-dependent effects on channel steady-state gating kinetics were observed. Only after disruption of the cytoskeleton with cytochalasin-D did we see significant chloride concentration-dependent shifts in gating kinetics. This suggests that the shift in gating kinetics is mediated through effects of intracellular chloride concentration on cytoplasmic domain tertiary conformation as cytoskeletal interaction appears to mask the effect. Furthermore, as cytoskeletal disruption only impacts channel gating kinetics at low physiological intracellular chloride concentrations, these studies highlight the importance of paying close attention to anion concentrations used under experimental conditions.

Evaluation of LEACHMN under dryland conditions. I. Simulation of water and solute transport

The ability to simulate the dynamics of soil nitrogen under field conditions will aid our understanding of the nitrogen cycle. Our objective was to test the water and solute components of LEACHMN using data obtained from a field lysimeter study conducted on a medium-textured soil in southwestern Saskatchewan, Canada. Our preliminary evaluation of LEACHMN showed that the retentivity and conductivity functions used in this model were not appropriate for our soil as the original model permitted water transmission through the soil profile too rapidly. We, therefore, incorporated the van Genuchten retentivity function into LEACHMN and used the same soil water retention data to generate the van Genuchten parameters. The modified model was able to reproduce changes in water and chloride concentration after minimal calibration. Overall, the value of 0.45 used for the pan coefficient for soil under fallow and 12 mm used for dispersivity produced a realistic estimation of changes in water and chloride within the soil in the 2 yr of the field experiment. The model reproduced soil water redistribution in a fallow system. There was a tendency to under-estimate soil water content during dry periods, mainly as a result of the model’s tendency to over-estimate evaporation. While the centre of mass of chloride was correctly estimated, the model under-estimated the maximum depth of chloride penetration due to a slight tendency to over-estimate evaporation. Based on our statistical and graphical evaluation of LEACHMN, the modified model is adequate for our subsequent nitrate leaching study. Key words: LEACHMN, lysimeter, dryland, water, chloride, nitrate

A Family of Acetylcholine-gated Chloride Channel Subunits in Caenorhabditis elegans

The genome of the nematode Caenorhabditis elegans encodes a surprisingly large and diverse superfamily of genes encoding Cys loop ligand-gated ion channels. Here we report the first cloning, expression, and pharmacological characterization of members of a family of anion-selective acetylcholine receptor subunits. Two subunits, ACC-1 and ACC-2, form homomeric channels for which acetylcholine and arecoline, but not nicotine, are efficient agonists. These channels are blocked by d-tubocurarine but not by alpha-bungarotoxin. We provide evidence that two additional subunits, ACC-3 and ACC-4, interact with ACC-1 and ACC-2. The acetylcholine-binding domain of these channels appears to have diverged substantially from the acetylcholine-binding domain of nicotinic receptors.

Hydration level monitoring using embedded piezoresistive microcantilever sensors

A new MEMS based sensor technology, embedded piezoresistive microcantilever (EPM) sensors, may be useful in the real-time monitoring of hydration levels in athletes or other individuals whose activities may result in dehydration. In these devices, organic polymers or functionalized polymeric materials respond to osmolality changes in a person's saliva by expanding or contracting volumetrically. These volumetric changes are measured by tiny piezoresistive microcantilevers embedded in the polymeric material. In this report, we have tested a prototype device utilizing UV crosslinked poly(vinyl acetate) as the active sensing material. This device was able to reliably respond to 1% changes in sodium chloride concentration in solution or alternately to 1% changes in relative humidity.

Serum Tonicity, Extracellular Volume and Clinical Manifestations in Symptomatic Dialysis-Associated Hyperglycemia Treated Only with Insulin

The absence of osmotic diuresis modifies the effects of hyperglycemia on body fluids in patients with advanced renal failure. To determine the relationship between clinical manifestations and abnormalities in tonicity and extracellular volume in such patients, we analyzed 43 episodes of severe dialysis-associated hyperglycemia (serum glucose exceeding 600 mg/dL) treated only with insulin. The main manifestations were dyspnea in 22 cases (pulmonary edema in 19), nausea and vomiting in 15, coma in 13 and seizures in 3, while 5 patients had no symptoms. Treatment with insulin resulted in a decrease in serum glucose value from 913 +/- 197 mg/dL to 170 +/- 78 mg/dL, an increase in serum sodium level from 125 +/- 5 to 136 +/- 5 mmol/L, and a fall in calculated serum tonicity value from 300 +/- 13 to 282 +/- 11 mmol/kg (all at p < 0.001). The ratio of the change in serum sodium level over change in serum glucose concentration was -1.50 +/- 0.22 mmol/L per 100 mg/dL. The percent increase in extracellular volume secondary to hyperglycemia developing from the prior euglycemic state and calculated from changes in serum sodium and chloride concentrations, was 10.9% +/- 4.6% (1.5% +/- 0.6% per 100 mg/dL increase in serum glucose level). All clinical manifestations dissipated after correction of hyperglycemia in 42 patients. One woman developed during treatment a fatal myocardial infarction. Dialysis patients with severe hyperglycemia may develop symptoms as a result of hypertonicity and extracellular expansion. Insulin alone may be sufficient treatment for these symptoms. The changes in serum tonicity and electrolytes during treatment are consistent with theoretical predictions.

Long-lasting changes in GABA responsiveness in cultured neurons

In neuronal cells, GABA evokes an increase in chloride conductance by activating GABA A and GABA C receptors. In mature neurons, this increase in conductance generally has a hyperpolarizing and inhibitory action. Using gramicidin-based perforated patch recordings, we show that in cultured motor neurons GABA-induced currents are significantly altered following activation of GABA receptors coinciding with changes in membrane potential. Changes in intracellular chloride concentration constituted the mechanism for this modulation. Because of low resting chloride conductance and low activity of chloride transporters, changes in intracellular chloride concentration and hence GABA response were long-lasting (time constant of recovery was about 2.5 min). Cultured dorsal horn and hippocampal neurons exhibited a similar response pattern, suggesting a general property of cultured neuronal cells. These long-lasting changes in GABA responsiveness may have major implications on neuronal excitability.

Neuronal nitric oxide synthase: its role and regulation in macula densa cells.

Macula densa (MD) cells detect changes in distal tubular sodium chloride concentration ([NaCl](L)), at least in part, through an apical Na:2Cl:K co-transporter. This co-transporter may be a site for regulation of tubuloglomerular feedback (TGF), and recently angiotensin II (Ang II) was shown to regulate the MD Na:2Cl:K co-transporter. In addition, nitric oxide (NO) produced via neuronal NO synthase (nNOS) in MD cells attenuates MD-TGF signaling. This study investigated [NaCl](L)-dependent MD-NO production, the regulation of co-transporter activity by NO, and the possible interaction of NO with Ang II. MD cell Na(+) concentration ([Na(+)](i)) and NO production were measured using sodium-binding benzofuran isophthalate and 4-amino-5-methylamino-2',7'-difluorescein diacetate, respectively, using fluorescence microscopy. Na:2Cl:K co-transport activity was assessed as the initial rate of increase in [Na(+)](i) when [NaCl](L) was elevated from 25 to 150 mM. 10(-4) M 7-nitroindazole, a specific nNOS blocker, significantly increased by twofold the initial rate of rise in [Na(+)](i) when [NaCl](L) was increased from 25 to 150 mM, indicating co-transporter stimulation. There was no evidence for an interaction between the stimulatory effect of Ang II and the inhibitory effect of NO on co-transport activity, and, furthermore, Ang II failed to alter MD-NO production. NO production was sensitive to [NaCl](L) but increased only when [NaCl](L) was elevated from 60 to 150 mM. These studies indicate that MD-NO directly inhibits Na:2Cl:K co-transport and that NO and Ang II independently alter co-transporter activity. In addition, generation of MD-NO seems to occur only at markedly elevated [NaCl](L), suggesting that NO may serve as a buffer against high rates of MD cell transport and excessive TGF-mediated vasoconstriction.

Over twenty years trend of chloride ion concentration in Lake Biwa

Recent increase of chloride ion concentration in Lake Biwa was considered. Over the past 20 years' data at the North Basin of Lake Biwa showed that chloride ion concentration has been continuously increasing from 7.4 to 9.9 mg l-1 at 0.5 m depth from lake surface and from 7.3 to 9.9 mg l-1 above the bottom (depth of over 80 m from lake surface). This low level salinity indicated, however, about 35% increase through 20 years. In this paper, we reported the trend and the tendency of chloride ion concentration at some locations and the change of climatic data through 20 years in Lake Biwa. In a short period within one year, chloride ion concentration clearly fluctuated in the upper water layer. This fluctuation was mostly influenced by precipitation. Similar trend of chloride ion concentration could be seen in the South Basin of Lake Biwa with much higher concentration than that in the North Basin. We also discussed the long-term changes of chloride concentrations in 5 major rivers with large catchment area, water level and precipitation. The data of river discharge indicated that some rivers in the southern part of the North Basin in Lake Biwa contain a relatively high chloride concentration compared with others. Furthermore, we proposed a simple conceptual model with variable outflow and inflow fluxes. This conceptual model expressed an amount of chloride budget. We estimated the average chloride flux flowing from the watershed into Lake Biwa using the data of chloride ion concentration in the lake and the data of water discharge from the lake. Comparing the results of the model analysis with the data of 12 major rivers contributing large flux to Lake Biwa, we suggested that river inflow is one of the major sources to induce the increase of chloride ion concentration in the lake, and the inflow from non-point source can be also important sources.

Double logarithmic, linear relationship between plasma chloride concentration and time since death in humans in Chandigarh Zone of North-West India

Estimation of time since death with the change in chloride concentration in postmortem blood is the topic of discussion in the study. Querido (Forensic Sci Int 45 (1990) 117) had demonstrated a highly significant double logarithmic linear relationship between the plasma chloride concentration and postmortem interval in Wistar rats. Henceforth, the present study was carried out to substantiate this propensity in humans. Chloride concentration in postmortem blood of 474 subjects revealed a highly significant relationship between logarithm of plasma chloride concentration and logarithm of the time since death during 3–58 h of death. Notwithstanding, time since death can be predicted from plasma chloride concentration with standard error of estimate of 2.1 h but factors like environmental temperature, cause of death, age and gender influences it significantly.

Macula densa cell signaling.

Macula densa cells are renal sensor elements that detect changes in distal tubular fluid composition and transmit signals to the glomerular vascular elements. This tubuloglomerular feedback mechanism plays an important role in regulating glomerular filtration rate and blood flow. Macula densa cells detect changes in luminal sodium chloride concentration through a complex series of ion transport-related intracellular events. NaCl entry via a Na:K:2Cl cotransporter and Cl exit through a basolateral channel lead to cell depolarization and increases in cytosolic calcium. Na/H exchange (NHE2) results in cell alkalization, whereas intracellular [Na] is regulated by an apically located H(Na)-K ATPase and not by the traditional basolateral Na:K ATPase. Communication from macula densa cells to the glomerular vascular elements involves ATP release across the macula densa basolateral membrane through a maxi-anion channel. The adaptation of multi-photon microscopy is providing new insights into macula densa-glomerular signaling.

Measuring the bioavailable/toxic concentration of copper in natural water by using anodic stripping voltammetry and Vibrio-qinghaiensis sp.Nov.-Q67 bioassay

Bioassays were carried out in the culture media for Vibrio-qinghaiensis sp.Nov.-Q67 and the influences of alkalinity and different concentrations of chloride, ethylene diamine tetraacetic acid (EDTA) and natural derived fulvic acid (FA) on the labile concentration and toxicity of Cu were investigated. The labile concentration of Cu was obtained by differential pulse anodic stripping voltammetry with a double acidification method (DAM-DPASV). Changes in water alkalinity and chloride concentrations did not affect the labile concentration of Cu, but increases of alkalinity and concentrations of chloride reduced the toxicity on Q67. In the presence of EDTA and FA, both labile concentration of Cu and toxicity were reduced. By excluding Cu-carbonate complexes and Cu-chloride from labile concentration, a bioavailable concentration of Cu (or [Cu*]) was obtained and used to predict the acute toxicity of Cu on Q67. For natural waters, the labile concentration of Cu was measured by DAM-DPASV and [Cu*] was calculated by a MINTEQ A2 software based on composition of waters. This procedure was tested for Guanting Reservoir waters by spiking different concentration Cu. The results showed that [Cu*] was a good indicator for Cu toxicity and could be used in field conditions.