Entry Of Chloride Research Articles

Structural, optical, second harmonic, and mechanical studies on zinc chloride added alpha-glycine crystals

The slow evaporation solution method was employed to synthesize and crystallize zinc chloride doped α-glycine (ZCAG) single crystals. The single crystal X-ray diffraction studies of pure α-glycine single crystals revealed that the structure belong to primitive monoclinic lattice. Powder X-ray diffraction studies of ZCAG showed the well-defined sharp peaks and formation of centrosymmetric structure with space group P21/n. The increase in lattice volume of ZCAG suggested that the access of zinc chloride into the α-glycine crystal and the entry of zinc chloride to the α-glycine crystal was also established from the energy-dispersive X-ray analysis. Fourier transform infrared spectrum of ZCAG revealed that the functional groups of α-glycine was not transformed due to the introduction of zinc chloride into the lattice. The optical transparency of ZCAG was observed in the UV–visible region, and it exhibited a superior transmittance in the visible region. Energy bandgap value was determined and found to changes while increasing the dopant concentration. An emission peak was observed in the violet region from the photoluminescence spectra. The centrosymmetric ZCAG exhibited second harmonic generation efficiency of 1.44 times higher than standard potassium dihydrogen phosphate, possibly due to local non-centrosymmetry in the lattice, which is further augmented by lattice distortion induced by the dopant. Low dielectric constant and loss of the grown ZCAG crystals showed the remarkable application of non-linear optical. The Meyer index indicates that the grown ZCAG are categorized as soft materials.

High- dose nitric oxide gas inhalation for HIV infection

Therapeutic effect of high-dose nitric oxide gas inhalation (NO concentration was not less than than 1000 ppm) on two patients with HIV infection was shown. Inhaled NO therapy led to a rapid decrease in viral load to an undetectable level which was persistent even after analytical treatment interruption. It is suggested that HIV infection is controlled by nitrosonium (NO+) cations, the oxidized form of neutral NO molecules that enter the blood. Subsequent conversion of NO+ cations into nitrite anions due to a reaction with hydroxyl ions is inhibited by the binding of NO+ cations and chloride anions leading to the formation of nitrosyl chloride in the blood. Further entry of nitrosyl chloride into cells and tissues ensures NO+ transfer to them. Interaction between nitrosyl chloride and thiols requires the appearance of relevant S-nitrosothiols as NO donors in cells and tissues.

Conditional deletion of KCC2 impairs synaptic plasticity and both spatial and nonspatial memory.

The postsynaptic inhibition through GABAA receptors (GABAAR) relies on two mechanisms, a shunting effect due to an increase in the postsynaptic membrane conductance and, in mature neurons, a hyperpolarization effect due to an entry of chloride into postsynaptic neurons. The second effect requires the action of the K+-Cl- cotransporter KCC2 which extrudes Cl- from the cell and maintains its cytosolic concentration very low. Neuronal chloride equilibrium seems to be dysregulated in several neurological and psychiatric conditions such as epilepsy, anxiety, schizophrenia, Down syndrome, or Alzheimer's disease. In the present study, we used the KCC2 Cre-lox knockdown system to investigate the role of KCC2 in synaptic plasticity and memory formation in adult mice. Tamoxifen-induced conditional deletion of KCC2 in glutamatergic neurons of the forebrain was performed at 3 months of age and resulted in spatial and nonspatial learning impairment. On brain slices, the stimulation of Schaffer collaterals by a theta burst induced long-term potentiation (LTP). The lack of KCC2 did not affect potentiation of field excitatory postsynaptic potentials (fEPSP) measured in the stratum radiatum (dendrites) but increased population spike (PS) amplitudes measured in the CA1 somatic layer, suggesting a reinforcement of the EPSP-PS potentiation, i.e., an increased ability of EPSPs to generate action potentials. At the cellular level, KCC2 deletion induced a positive shift in the reversal potential of GABAAR-driven Cl- currents (EGABA), suggesting an intracellular accumulation of chloride subsequent to the downregulation of KCC2. After treatment with bumetanide, an antagonist of the Na+-K+-Cl- cotransporter NKCC1, spatial memory impairment, chloride accumulation, and EPSP-PS potentiation were rescued in mice lacking KCC2. The presented results emphasize the importance of chloride equilibrium and GABA-inhibiting ability in synaptic plasticity and memory formation.

Modulation of proton-activated chloride (PAC) channel by PIP2

PAC channel is an evolutionarily conserved pH-gated chloride ion channel. Its activity at the plasma membrane is widely observed across different tissues. Under pathological conditions associated with acidosis, such as ischemic stroke, PAC at the cell surface is activated by a drop in tissue pH, allowing the entry of chloride into the cells, which in turn causes cell swelling and contributes to acid-induced brain injury. PAC also traffics to endosomes, where it regulates lumen acidification. Threshold for PAC activation depends on its subcellular localization, so we hypothesized that PAC channel is regulated by phosphatidylinositol PI(4,5)P2 lipid that is exclusively present in the plasma membrane.

Influence of mono- and divalent salts on water loss and properties of dry salted cod fillets

Salted cod is a product highly appreciated by consumers, especially in Southern Europe and Latin America. In recent years there has been increasing consumer demand for products with low sodium content, and this has led the salting industry to seek new salt mixtures to help to reduce Na+ levels without producing alterations in the properties of the final product. In this study, Atlantic cod (Gadus morhua) was initially brined with various mixtures of salts based on NaCl, at various pH levels and including KCl, MgCl2 and/or CaCl2. After subsequent dry salting with NaCl, the Na+, K+, Ca2+ and Mg2+ cation contents were evaluated, and also their effect on water loss, salt uptake, entry of chloride, water holding capacity (WHC), water extractable protein (WEP) and hardness of the end product. A greater presence of K+ in muscle was associated with greater water loss, salt uptake and hardness of the dry salted product. Moreover, incorporation of Ca2+ and Mg2+ negatively affected water holding capacity. These changes were not dependent on brine pH and might significantly alter the acceptability of the final product.

Unraveling the relationship between macula densa cell volume and luminal solute concentration/osmolality

At the macula densa, flow-dependent changes in luminal composition lead to tubuloglomerular feedback and renin release. Apical entry of sodium chloride in both macula densa and cortical thick ascending limb (cTAL) cells occurs via furosemide-sensitive sodium-chloride-potassium cotransport. In macula densa, apical entry of sodium chloride leads to changes in cell volume, although there are conflicting data regarding the directional change in macula densa cell volume with increases in luminal sodium chloride concentration. To further assess volume changes in macula densa cells, cTAL-glomerular preparations were isolated and perfused from rabbits, and macula densa cells were loaded with fluorescent dyes calcein and 1-(4-trimethylammoniumphenyl)-6-phenyl-1,3,5-hexatriene p-toluenesulfonate. Cell volume was determined with wide-field and multiphoton fluorescence microscopy. Increases in luminal sodium chloride concentration from 0 to 80 mmol/l at constant osmolality led to cell swelling in macula densa and cTAL cells, an effect that was blocked by luminal application of furosemide. However, increases in luminal sodium chloride concentration from 0 to 80 mmol/l with concomitant increases in osmolality caused sustained decreases in macula densa cell volume but transient increases in cTAL cell volume. Increases in luminal osmolality with urea also resulted in macula densa cell shrinkage. These studies suggest that, under physiologically relevant conditions of concurrent increases in luminal sodium chloride concentration and osmolality, there is macula densa cell shrinkage, which may play a role in the macula densa cell signaling process.

Ring Opening and Displacement by Chloride of the Bidentate Chelate Ligand from Dichloro[pyridine‐2‐(α‐methoxymethanolato)]gold(III) – A Kinetic and Mechanistic Study

AbstractThe kinetics of ring opening and displacement of the bidentate chelate ligand from dichloro[pyridine‐2‐(α‐methoxymethanolato)]gold(III) [Au(N–O)Cl2] (1) have been studied spectrophotometrically in methanol/water (95:5, v/v) at 25 °C and constant ionic strength (I = 1 mol dm–3, LiClO4). In the presence of LiCl and perchloric acid the reaction consists of a pre‐equilibrium protonation of the coordinated oxygen followed first by ring opening at oxygen accompanied by the entry of chloride or solvent and fast acetalisation of the hemiacetalic form of the ligand to give [AuCl3(N–OMe)], and then by displacement of the N‐bonded ligand to give [AuCl4]–. The ligand is not displaced in the absence of chloride and no reaction is observed in the presence of chloride alone.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

Inhibition of chloride secretion in human bronchial epithelial cells by cigarette smoke extract

Chronic bronchitis, a disease mainly of cigarette smokers, shares many clinical features with cystic fibrosis, a disease of altered ion transport, suggesting that the negative effects of cigarette smoke on mucociliary clearance may be mediated through alterations in ion transport. We tested the hypothesis that cigarette smoke extract would inhibit chloride secretion in human bronchial epithelial cells. In agreement with studies in canine trachea, cigarette smoke extract inhibited net chloride secretion without affecting sodium transport. We performed microelectrode impalements and impedance analysis studies to investigate the physiological mechanisms of this inhibition. These data demonstrated that cigarette smoke extract caused an acute increase in membrane resistances in conjunction with apical membrane hyperpolarization, an effect consistent with inhibition of an apical membrane anion conductance. After this acute phase, both membrane resistances decreased while membrane potentials continued to hyperpolarize, indicating that cigarette smoke extract also inhibited the basolateral entry of chloride into the cell. Furthermore, cigarette smoke extract caused an increase in mucin secretion. Therefore, the ion transport phenotype of human bronchial epithelial cells exposed to cigarette smoke extract is similar to that of cystic fibrosis epithelia in which there is sodium absorption out of proportion to chloride secretion in the setting of increased mucus secretion.

Analysis of energy metabolism and mechanism of loop diuretics in the thick ascending limb of Henle's loop in dog kidneys.

The thick ascending limb of Henle's loop (TALH) absorbs up to 40% of filtered NaCl in volume-expanded dogs. To examine if a fraction of this absorption is passive, NaHCO3 absorption and associated NaCl absorption in proximal tubules were inhibited by acetazolamide, a carbonic anhydrase inhibitor. Ouabain, a specific inhibitor of Na,K-ATPase activity, reduced the remaining NaCl absorption and renal oxygen consumption in a ratio DeltaNa/DeltaO2 = 18, as expected for active transport. However, the responses to two loop diuretics were DeltaNa/DeltaO2 = 24 for ethacrynic acid and DeltaNa/DeltaO2 = 30 for bumetanide. Both loop diuretics induced potassium secretion. By superimposing ouabain potassium secretion was stopped and DeltaNa/DeltaO2 = 18 restored. Replacement of half of the circulating NaCl with Na2SO4 gave stop-flow pattern similar to those obtained after ethacrynic acid. Low entry of some sodium ions thorugh the apical membrane is permitted despite low chloride supply or blockade by loop diuretics of chloride entry by the Na-K-2Cl transporter. Continued Na-K-ATPase activity causes secretion of potassium ions through the apical ion channel, ethacrynic acid being more kaliuretic and less natriuretic than bumetanide. Greater paracellular recycling of sodium ions after bumetanide maintains ionic balance. In contrast, under normal conditions excess entry of chloride by the Na-K-2Cl-transporter leads to paracellular back-diffusion of chloride rather than paracellular absorption of sodium ions, consistent with DeltaNa/DeltaO2 = 18 after ouabain. Thus all NaCl transport along TALH is active in vivo, whereas absorption of other cations, such as lithium, probably is passive.

Effects of Ionizing Radiation and Aluminum Chloride on Protein of Glial Intermediate Filaments in the Rat Brain

We studied the effects of irradiation with X-rays (the total dose of 0.0129 C/kg was attained over 7, 14, or 21 days), increased entry of Al3+ into the organism (0.2% AlCl3 in drinking water), and the combined influence of these factors for 21 days on the contents of the soluble and filamentous forms of glial fibrillary acidic protein (GFAP) in the tissues of the hippocampus, cerebellum, and neocortex of albino rats. After irradiation for 7 days, a clear trend toward drops in the GFAP contents in the structures under study was observed, while irradiation in the same dose, but for 14 or 21 days, resulted in increases in the contents of both GFAP forms (within a range of 13-29%, as compared with the control). Entry of aluminum chloride with water also resulted in an increase in the GFAP contents in all studied structures; changes in the filamentous form were more intensive. The combined influence of irradiation and Al3+ resulted in more intensive shifts in the GFAP levels; the content of its filamentous form increased in all structures by about 50%, while shifts of the soluble form were somewhat smaller.

Apical membrane sodium and chloride entry during osmotic swelling of renal (A6) epithelial cells

To assess the role of chloride in cell volume and sodium transport regulation, we measured cell height changes (CH), transepithelial chloride and sodium fluxes, and intracellular chloride content during challenge with hyposmotic solutions under open circuit (OC) conditions. CH maximally increased following hyposmotic challenge within approximately 5 minutes. The change in CH was smaller under short circuit (SC) conditions or following replacement of chloride in the mucosal solution by gluconate or cyclamate (Cl(-)-freem). When corrected for the osmotically inactive cell volume (30 +/- 2%), delta CH for controls (OC) were greater than predicted for an ideal osmometer. In contrast, delta CH for Cl(-)-freem or SC conditions were similar to that predicted for an ideal osmometer. Na+ and Cl- mucosa-to-serosa fluxes increased following hyposmotic challenge. Chloride fluxes increased maximally within 5 min, then decreased. In contrast, the Na+ flux increased slowly and reached a steady state after approximately 25 min. Under isosmotic conditions, exposure to Cl(-)-freem solutions led to decreases in the transepithelial conductance, Na+ flux, and CH. Chloride permeabilities in the apical and basolateral membranes were detected using the fluorescent intracellular chloride indicator MQAE. The results indicate that during osmotic swelling, the entry of both sodium and chloride is increased. The time courses of these increases differ, suggesting distinct mechanisms for the osmotic regulation of these apical membrane transport processes.

Effect of buffers and osmolality on anion uniport across the mitochondrial inner membrane

The effects of buffers and osmolality of the suspending medium on the pH-dependent anion uniport across the inner membrane of isolated rat liver mitochondria have been studied using the light scattering technique to measure passive osmotic swelling. In contrast to some other transport processes the rates of entry of chloride and other anions via the anion-conducting channel decreased steeply with increasing solute concentration. This effect appears to be a result of increased osmolality or decreased matrix volume rather than inhibition by the anion since it was also produced by increasing the osmolality by addition of non-penetrant solutes. The effects of some pH buffers on the mitochondrial anion-conducting channel were also investigated. Some zwitterionic buffers had little effect other than that produced by increasing osmolality but Tricine, Popso and Caps produced marked additional inhibition of anion uniport and several other zwitterionic buffers were also inhibitory. The correlation between increased anion conductivity and increased matrix volume supports the proposal that this channel functions in regulation of the volume of the mitochondrial matrix.

Microelectrode studies on Malpighian tubule cells of Locusta migratoria: Effects of external ions and inhibitors

Basal and apical membrane potentials were recorded from Malpighian tubules of Locusta using intracellular microelectrodes. Ion substitution experiments, involving Na +, K + and Cl − in the bathing media, indicated that the basal membrane was more permeable to K + than Na + or Cl −. Two different electrical responses to high [K +] salines were noted and these probably reflect distinct physiological states of basal membrane permeability. Experiments with ouabain and orthovanadate suggested that whilst (Na + + K +)-ATPase activity was not significantly electrogenic, asymmetric ionic distribution across the basal membrane was partly maintained by this enzyme. The actions of furosemide and bumetanide indicated that chloride might cross the basal membrane by a cation co-transport mechanism. In addition, data from ion substitution experiments suggest that Cl − entry across the basal membrane is K +-dependent. The responses to Na +-free and Cl −-free salines bring into question the role of Na + in the entry of chloride across the basal membrane by co-transport.

Displacement of pyridine-2-methanol from dichloro(pyridine-2-methanolato)gold(III) in acidic solution. Ring opening at oxygen

The kinetics of the displacement of pyridine-2-methanol (N–OH) from dichloro(pyridine-2-methanolato)gold(III), [Au(N–O)Cl2], have been studied in 5% aqueous methanol at 25 °C. In the presence of LiCl and perchloric acid the reaction consists of a pre-equilibrium protonation of the oxygen followed, first, by ring opening at oxygen accompanied by the entry of chloride or solvent, and then by displacement of the N-bonded pyridine-2-methanol to give [AuCl4]–. This final stage is very similar to the displacement of 2-(methoxymethyl)pyridine (N–OMe) from [Au(N–OMe)Cl3]. The ligand is not displaced in the absence of chloride. The reaction between [AuCl4]– and excess pyridine-2-methanol in 5% aqueous methanol was also studied at 25 °C. The initial attachment of the ligand by nitrogen is followed by rapid ring closing and a second molecule of ligand enters more slowly. The final product is [Au(N–O)2]+(isomeric form unknown), stabilised by the basic conditions generated by the excess ligand. Monodentate pyridine-2-methanol behaves as if it has a pKa of 5.6 with a steric hindrance comparable to that of 2-methylpyridine.

Mediators of the secretory response to kinins.

The output of immunoreactive (i) 6 keto prostaglandin F1 alpha (i6ketoPGF1 alpha), iPGE2 and ithromboxane B2 (iTXB2) from isolated colonic epithelium of the rat into the apical and basolateral bathing solution has been measured. In some instances tissues were also voltage clamped at 0 mV to measure short circuit current (SCC). Kallidin (lysylbradykinin) stimulated the output of all three eicosanoids, specifically from the basolateral face of the tissue. The output was similar whether or not the tissues were short circuited. Both the SCC response and eicosanoid output were dependent upon the concentration of kallidin, but not in a strictly proportional manner, there being relatively more eicosanoid output at submaximal kinin concentrations. Indomethacin, 5 microM, abolished the eicosanoid output, in response to kinin, while some part of the SCC response remained. Calcium removal from the basolateral bathing fluid severely attenuated the SCC response, reduced the output of i6ketoPGF1 alpha to half, but left the output of iPGE2 unchanged. In the presence or absence of calcium it is probable that sufficient PGE material is released to cause part of the SCC changes seen with kinin. Kinin and PGE1 increased the cyclic AMP content of intact epithelia, provided a phosphodiesterase inhibitor was added at the same time. It is proposed that kinin causes an increase in calcium influx at the basolateral pole of the tissue. This calcium is necessary for the production of some eicosanoids and the subsequent generation of cyclic AMP, which then increases apical chloride permeability. In addition, calcium may facilitate entry of chloride through the basolateral face of the cells by activating a cotransport mechanism.

Effect of external sodium on intracellular chloride activity in the surface cells of frog gastric mucosa. Microelectrode studies.

The intracellular chloride activity and its dependence on ionic substitutions in the bathing media was studied in individual surface cells of resting gastric mucosa using conventional and Cl- selective microelectrodes. When the tissue was perfused with control NaCl-Ringer the cell membrane p.d.'s, cell-lumen (psi cm) and cell-serosa (psi cs) were -40.9 +/- 0.6 mV and -66.8 +/- 0.5 mV (n = 175) respectively and the p.d. measured by the Cl- selective microelectrodes across the serosal membrane (psi csCl-) averaged -32.4 +/- 0.7 mV (n = 138). From these values an intracellular Cl- activity (acCl-) of 15.3 mmol/l can be estimated. The data indicate that chloride ion is distributed close to equilibrium at the luminal membrane while it is accumulated by an energy requiring step at the serosal membrane. Reduction (2 mmol/l) or absence of chloride from the luminal bath did not result in any detectable change of acCl-; on the other hand, after removal of Cl- from the serosal bath the intracellular Cl- activity fell to 7.1 mmol/l. When the tissue was exposed to serosal Na+-free Ringer (Na+ replaced by choline or TMA), although the acCl- remained unaffected, a marked reduction of the electrochemical gradient for Cl- at the serosal membrane was observed. These data indicate that: chloride is accumulated in the surface cells against its electrochemical potential difference at the serosal membrane; the luminal membrane has a negligible conductance to Cl-, while the serosal membrane represents a conductive pathway to chloride; the uphill entry of chloride at the serosal membrane seems to be, at least partially, Na+-dependent.

The bovine lens as an ion-exchanger: a comparison with ion levels in human cataractous lenses

Changes in the ion concentrations of the freeze-fractured bovine lens following incubation in an isotonic salt solution, follow similar trends to those found in human cataractous lenses when the data are expressed as a function of the internal sodium. The rise in sodium is accompanied by a fall in potassium, while there is a delay (relative to sodium) in the entry of chloride and a similar, but more pronounced, delay in the calcium entry. The magnesium concentration in both systems remains relatively constant while these changes are occurring. The diffusion coefficient of calcium in the freeze-ruptured lens is about one-tenth that of the free solution value, implying a considerable interaction between calcium and certain molecular species in the lens. Although the equilibrium concentration of calcium in the bovine lens is over five times that of the bathing solution, the level is still far below that found in many human cataracts. The relatively high levels of calcium and magnesium cannot be accounted for on a Donnan distribution basis alone. Addition of EGTA to the bathing solution prevents the rise in lens calcium in the bovine system. Lenses with low internal calcium levels are more transparent than those in which the calcium concentration is allowed to rise.

An in vitro investigation of the anodic polarization and capacitance behavior of 316-L stainless steel.

Determinations were made of how the corrosion-resistant properties of the passive film on 316-L stainless steel are influenced by the material's mechanical and surface states, and the variable pH and PO2 conditions of the interstitial fluid. Cold-rolled and annealed specimens were surface-prepared, commercially and in the laboratory, respectively, as if for orthopedic implantation. Passive film behavior was studied by the anodic polarization and pulse-potentiostatic capacitance methods. The pH and PO2 of the Ringer's test solution were varied to include interstitial fluid values occurring postoperatively and onto recovery. The anodic polarization behavior of all specimens was found to be pH- and PO2-independent. Breakdown potentials of annealed specimens were 800-950 mV (SCE), in contrast to previously reported values of approximately 350 mV. This substantial increase is related to the influence of surface preparation and, in particular, to the optimization of electropolishing time which acts to produce a microscopically smooth surface, free of debris and disarrayed material. Capacitance behavior of annealed material for potentials greater than 400 mV was consistent with a model involving the entry of chloride and metal ions (mostly Fe) into the passive film. This entry is related to the onset of pitting.

Sodium and chloride fluxes in synaptosomes in vitro.

Abstract—Synaptosomes incubated in a physiological saline extrude sodium and take up potassium. As would be expected this process is completely blocked by metabolic inhibitors such as cyanide and iodoacetate. However, when metabolic inhibitors are replaced by ouabain (100 μM) there is an increase in the steady state intrasynaptosomal sodium and chloride content even though there is no change in the potassium content. The increases are prevented when synaptosomes are incubated with metabolic inhibitors in addition to ouabain. There is therefore a ouabain‐insensitive process that transports sodium, chloride and concomitantly water into synaptosomes. It appears not to function when the supply of metabolic energy is inhibited. The diuretic furosemide (1 mM) in the presence of ouabain inhibits the entry of sodium and chloride without affecting the intrasynaptosomal potassium concentration. Ethacrynic acid (1 mM) has a somewhat similar effect but in addition appears to damage the synaptosome membrane.Kinetic measurements were made of the uptake of sodium, potassium and chloride under conditions of metabolic inhibition and the permeability constants of the membrane determined. Values of 0.068, 0.117 and 0.032 × 10‐6 (cm s‐1) were found for the permeability constants of the membrane to (respectively) sodium, potassium and chloride. Measurements of the rate of uptake in the presence of ouabain revealed an inwardly directed sodium and chloride flux of 5‐20 pmol cm‐2 s‐1. Calculation of the fluxes from the steady state ion concentrations also reveals an inwardly directed sodium and chloride flux, though of lesser magnitude. The influx of water is less than would be expected to preserve osmotic equality suggesting that the translocation of sodium and chloride is the primary event. Although its function remains uncertain the flux has a considerable effect on the ion content of synaptosomes.

Passage of pyridinium oximes into human red cells

Contrary to popular views, pralidoxime chloride, a positively charged oxime and a drug used to treat poisoning from organophosphorus insecticides, penetrates the red cell membrane. Two other therapeutically related drugs that have similar dissociation constants and chemical function groupings penetrate to negligible extents. Pralidoxime chloride did not bind to either red cell stroma or hemoglobin. The rate of entry into red cells by pralidoxime chloride did not change when the pH of blood was changed by ± 0.6 pH unit. Since the rate of entry of pralidoxime chloride into red cells from plasma was identical to the rate at which oxime passed from red cells into plasma, the process was likely due to simple diffusion. In addition, the fraction of pralidoxime chloride entering the red cells was independent of drug concentration. The penetration was not affected by active transport inhibitors, such as ouabain or N-methyl maleimide. The selective penetration could not be related to lipid solubility.