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At least 127 records · Page 7Linked to original sources

GABA-gated chloride ion influx in brains of epileptic El mice.

GABA-gated chloride ion influx was measured in brain "microsac" preparations of epileptic El mice. There was significantly greater sensitivity to GABA in stimulated El mice (which had 14-18 convulsions induced at weekly intervals) than in unstimulated El mice (which had not experienced convulsions) or ddY mice. GABA-gated chloride ion influx was significantly decreased 20 min after a single convulsion, and returned to the preconvulsion level 60 min after a convulsion. These findings suggest that the functional state of GABA-gated chloride channel in El mice is changed secondarily by single or repeated convulsions.

Animals↗

Effects of intracellular calcium on lens membrane permeability.

The present investigation was designed to assess whether lens membrane permeability is affected by changes in levels of intracellular calcium. Lanthanum, an inhibitor of Ca-ATPase, affected an increase in the concentration of intracellular calcium (Cai) measured in cortical fiber cells. Preculture of lenses in lanthanum (1.0mM) caused an accumulation of 36Cl during subsequent culture at a rate three-fold higher than control lenses. Changes in calcium levels, however, were not responsible for the observed flux changes because a 40mV depolarization was observed to occur prior to a significant increase in calcium levels. The non-specific effects of lanthanum and other potential inhibitors of calcium transport were avoided by preculturing lenses in an ion-HEPES medium containing 20mM calcium chloride. In lenses with a six-fold increase in calcium levels there resulted only a 10% increase in 36Cl uptake over a 3 hr period. 86Rb efflux was also measured and the rate constant was unchanged compared to control lenses. Calcium accumulation did lead to a small (8mV) depolarization which may account for the small increase in chloride accumulation. By light microscopy, morphology of cortical lens fibers and the epithelium appeared unchanged in the calcium-loaded lens. The results provide little evidence that an increase in Cai leads to acute changes in lens membrane permeability.

Body Fluids↗

Study of lithium absorption by users of spas treated with lithium ion.

This study examines the possible dermal absorption of lithium ion into the blood serum of spa/hot tub bathers. Fifty-three participants (28 males and 25 females) spent 20 minutes per day, 4 days per week for 2 consecutive weeks in one of two assigned spas. The participants were randomly assigned to one of the two spas after matching based on sex, age, and use of oral contraceptives. The test spa contained 40 +/- 5 ppm lithium ion, while the control spa contained no additional lithium ion above the background levels of approximately 0.02 ppm. The exposure in the spa treated with lithium ion (from lithium chloride) simulated the maximum exposure that would be expected in a spa sanitized with lithium hypochlorite. The two spas were maintained at 101 +/- 2 degrees F. Serum lithium ion levels before and after spa use were determined using graphite-furnace atomic absorption spectroscopy with a minimum detectable level of lithium ion in serum of 2 micrograms l-1 (ppb). There was no statistically significant difference in serum lithium levels between the control and treatment group at any stage. We conclude that dermal exposure to lithium ion (as would be present after treatment of a spa with lithium hypochlorite) did not result in a detectable increase in the serum lithium ion level.

Baths↗

pH-modulation of chloride channels from the sarcoplasmic reticulum of skeletal muscle.

The understanding of the role of cytoplasmic pH in modulating sarcoplasmic reticulum (SR) ion channels involved in Ca2+ regulation is important for the understanding of the function of normal and adversely affected muscles. The dependency of the SR small chloride (SCl) channel from rabbit skeletal muscle on cytoplasmic pH (pHcis) and luminal pH (pHtrans) was investigated using the lipid bilayer-vesicle fusion technique. Low pHcis 6.75-4.28 modifies the operational mode of this multiconductance channel (conductance levels between 5 and 75 pS). At pHcis 7.26-7.37 the channel mode is dominated by the conductance and kinetics of the main conductance state (65-75 pS) whereas at low pHcis 6.75-4.28 the channel mode is dominated by the conductance and kinetics of subconductance states (5-40 pS). Similarly, low pHtrans 4.07, but not pHtrans 6.28, modified the activity of SCl channels. The effects of low pHcis are pronounced at 10(-3) and 10(-4) M [Ca2+]cis but are not apparent at 10(-5) M [Ca2+]cis, where the subconductances of the channel are already prominent. Low pHcis-induced mode shift in the SCl channel activity is due to modification of the channel proteins that cause the uncoupling of the subconductance states. The results in this study suggest that low pHcis can modify the functional properties of the skeletal SR ion channels and hence contribute, at least partly, to the malfunction in the contraction-relaxation mechanism in skeletal muscle under low cytoplasmic pH levels.

Animals↗

Inhibition of hepatic azo-reductase and aromatic hydroxylase by radiopharmaceuticals containing tin.

Mice given single i.v. doses of some radiopharmaceuticals containing stannous chloride as a reducing agent, showed significant inhibition of hepatic azo-reductase and aromatic hydroxylase activity at dose levels which contained as little as 0.2 mg/kg of stannous chloride. Cytochrome P-450 content was also reduced significantly. Some of the above radiopharmaceuticals would have to be injected at approx. 10 times the maximum recommended human dose to reach a 0.2 mg/kg dose level of stannous chloride in man, provided other sources of stannous ion were excluded.

Aniline Hydroxylase↗

Salicylate-selective membrane electrode based on tin(IV) tetraphenylporphyrin.

The response properties of a new solvent/polymeric membrane electrode with unique selectivity toward anionic salicylate are reported. The electrode is prepared by incorporating 5, 10, 15, 20-tetraphenyl(porphyrinato)tin(IV) dichloride (Sn[TPP]Cl2) into a plasticized poly(vinyl chloride) membrane. The resulting sensor exhibits an anti-Hofmeister selectivity pattern, with high specificity for salicylate over lipophilic inorganic anions (perchlorate, periodate, thiocyanate, iodide, etc.) and biological organic anions (citrate, lactate, acetate). Moderate selectivity over structural analogues of salicylate (3- and 4-hydroxybenzoate, benzoate) is also observed. Radiotracer uptake experiments using [14C]salicylate clearly show that the metal center of the metalloporphyrin is critical for selective salicylate transport in the membrane phase. Minimal response to chloride ions makes the new electrode potentially useful for estimating salicylate levels in biological samples.

Electrodes↗

New halide-centered discrete Ag(I)(8) cubic clusters containing diselenophosphate ligands, [Ag(8)(X)[Se(2)P(OR)(2)](6)](PF(6)) (X = Cl, Br; R = Et, Pr, (i)Pr): syntheses, structures, and DFT calculations.

Six clusters Ag(8)(micro(8)-X)[Se(2)P(OR)(2)](6)(PF(6)) (R = Et, X = Cl, 1a, X = Br, 1b; R = Pr, X = Cl, 2a, X = Br, 2b; R = (i)Pr, X = Cl, 3a, X = Br, 3b) were isolated from the reaction of [Ag(CH(3)CN)(4)](PF(6)), NH(4)[Se(2)P(OR)(2)], and Bu(4)NX in a molar ratio of 4:3:1 in CH(2)X(2). Positive FAB mass spectra show m/z peaks at 2573.2 for 1a, 2617.3 for 1b, 2740.9 for 2a, 2786.9 for 2b, 2742.3 for 3a, and 2787.0 for 3b due to respective molecular cation, (M - PF(6))(+). (31)P NMR spectra of 1a-3b display a singlet at delta 82.3, 81.5, 82.9, 81.7, 76.3, and 75.8 ppm with a set of satellites (J(PSe) = 661, 664, 652, 652, 656, and 656 Hz, respectively). The X-ray structure (1a-2b) consists of a discrete cationic cluster in which eight silver ions are linked by six diselenophosphate ligands and a central micro(8)-Cl or micro(8)-Br ion with a noncoordinating PF(6)(-) anion. The shape of the molecule is a halide-centered distorted Ag(8) cubic cluster. The dsep ligand exhibits a tetrametallic tetraconnective (micro(2), micro(2)) coordination pattern, and each caps on a square face of the cube. Each silver atom of the cube is coordinated by three selenium atoms and the central chloride or bromide ion. Additionally, molecular orbital calculations at the B3LYP level of the density functional theory have been carried out to study the Ag-micro(8)-X (X = Cl, Br) interactions for cluster cations [Ag(8)(micro(8)-X)[Se(2)P(OR)(2)](6)](+). Calculations show very weak bonding interactions exist between micro(8)-X and Ag atoms of the cube.

Journal Article↗

Study of brain electrolytes and organic osmolytes during correction of chronic hyponatremia. Implications for the pathogenesis of central pontine myelinolysis.

Osmotic injury induced by rapid correction of severe chronic hyponatremia has been implicated in the development of central pontine myelinolysis. Organic osmolytes known previously as "idiogenic osmoles" accumulate intracellularly to protect cells from osmotic injury. We investigated the changes of these organic osmolytes as well as electrolytes in the brain during the induction and correction of chronic hyponatremia. Using 1H-nuclear magnetic resonance spectroscopy and HPLC, we found that in rats with chronic hyponatremia (3 d, serum sodium = 109 +/- 3 meq/liter), brain concentrations of myoinositol (41%), glycerophosphorylcholine (45%), phosphocreatine/creatine (60%), glutamate (53%), glutamine (45%), and taurine (37%) were all significantly decreased compared with control values (percentage control value shown, all P less than 0.01). The contribution of measured organic osmolytes and electrolytes to the total brain osmolality change was 23 and 72%, respectively. With rapid correction by 5% NaCl infusion, significant brain dehydration and elevation of brain Na and Cl levels above the normal range occurred at 24 h. These changes were not seen with slow correction by water deprivation. Reaccumulation of most organic osmolytes except glycerophosphorylcholine is delayed during the correction of hyponatremia and is independent of the correction rate of serum sodium. It is concluded that: most of the change of brain osmolality in chronic hyponatremia can be accounted by the changes in organic osmolytes and brain electrolytes; and rapid correction of hyponatremia is associated with an overshoot of brain sodium and chloride levels along with a low organic osmolyte level. The high cerebral ion concentrations in the absence of adequate concentrations of organic osmolytes may be relevant to the development of central pontine myelinolysis.

Animals↗

[The role of potassium and chlorine ions in the gas-transport function of the erythrocytes].

The research of electrolytes influence on blood gas-transport function was carried out on blood samples taken from human finger. It was shown that in the absence of blood system diseases, with pH indices, hemoglobin content, HCO3-, Na+ concentration in blood within physiological norm, partial pressure of oxygen and hemoglobin saturation by oxygen is clearly determined by concentration gradient of chlorine ions on erythrocytes membrane, that is by oxygen transport through the erythrocyte membrane, which is attended by the transfer of chlorine ions. Under these conditions there are two levels of PO2 indices and hemoglobin saturation by oxygen, depending on the concentration gradient of chlorine ions on the erythrocyte membrane, that are determined by K(+)- and Cl(-)-ions concentrations level in the blood and erythrocytes.

Biological Transport↗

Salt stress-induced chloride flux: a study using transgenic Arabidopsis expressing a fluorescent anion probe.

Salt stress leads to massive accumulation of toxic levels of Na(+) and Cl(-) ions in plants. By using the recombinant fluorescent probe CLOMELEON, we demonstrate passive anion flux under salt stress. Chloride influx is restricted in the presence of divalent cations like Mg(2+) and Ca(2+), and completely blocked by La(3+). The amount but not the rate of the reported chloride uptake is independent from the kind of corresponding permeable cation (K(+) versus Na(+)), external pH and magnitude of osmotic stress. Cl(-) efflux however seems to involve stretch-activated transport. From the influence of Ca(2+) on reported changes of cytosolic anion concentrations, we speculate that transport mechanisms of Cl(-) and Na(+) might be thermodynamically coupled under saline conditions.

Arabidopsis↗

Eprazinone alters lung lavage lipid levels and transtracheal ion transport.

Eprazinone therapy improves pulmonary function and arterial pO2 in patients with chronic bronchitis; however, the mechanism of action is unknown. The purpose of this study was to determine if eprazinone alters either lung surfactant levels in bronchoalveolar lavage fluid (BAL) of normal rats, or ion transport across canine tracheal epithelium mounted in Ussing chambers. In the surfactant studies, normal rats were force fed three doses (50, 100, and 200 mg/kg) of eprazinone for 4 days. Eprazinone at a dose of 200 mg/kg significantly increased total and individual (with the exception of phosphatidylinositol) phospholipid levels and decreased total neutral lipids. Lower doses of eprazinone significantly decreased neutral lipid levels without affecting the phospholipids. There was no change in BAL levels of protein or cells and no abnormal histology. In airway epithelial studies, mucosal addition of eprazinone produced a dose-dependent partially reversible decrease in short-circuit current (Isc). The decrease in Isc at lower eprazinone concentrations was accounted for entirely by a decrease in net chloride secretion while at higher concentrations both sodium and chloride transport were affected. Submucosal eprazinone had no affect on ion transport. These studies suggest that eprazinone influences both BAL lipid levels and ion transport, either of which could lead to a beneficial therapeutic effect.

Absorption↗

Thermoacclimatory changes in the ionic microenvironment of haemoglobin in the stenothermal rainbow trout (Salmo gairdneri) and eurythermal carp (Cyprinus carpio).

1. Haematological characteristics (erythrocyte number, haematocrit, haemoglobin, mean erythrocyte volume and haemoglobin content) and plasma and packed red blood cell water and electrolyte (Na+, K+, Ca2+, Mg2+, Cl-) levels were determined in summer and winter populations of rainbow trout acclimated to 2, 10 and 18 degrees C, and for carp held at 2, 16 and 30 degrees C. Erythrocyte electrolyte concentrations and ion:haemoglobin ratios were calculated from these data. 2. Modest increases in red cell abundance and reductions in mean erythrocytic volume were the most obvious haematological changes accompanying acclimation to higher temperatures. Haemoglobin levels in carp also tended to increase with temperature. 3. In winter trout plasma sodium and potassium were elevated following acclimation to increased temperature. No significant cges in plasma composition were observed in summer fish. Carp held at higher temperatures were characterized by increases in plasma chloride and calcium and reductions in sodium and magnesium levels. 4. Red cell potassium and magnesium and K+:Hb and Mg2+:Hb ratios tended to be higher in winter than in summer trout, with the converse being true of chloride and calcium and Cl-:Hb and Ca2+:Hb. Only potassium and K+:Hb were significantly altered following acclimation; rising at higher temperatures. In carp, potassium and K+:Hb were relatively thermostable, but sodium and chloride and Na+:Hb and Cl-:Hb increased with temperature while magnesium and Mg2+:Hb decreased. Changes in the ionic composition of carp red cells support the suggestion that cellular pH is reduced in the warm-acclimated animal. 5. These variations may be of adaptive value. Increases in chloride and hydrogen ion commonly reduce haemoglobin=oxygen affinity, and should facilitate oxygen unloading at the tissue level. Reductions in cellular magnesium, by maximizing organophosphate modulator levels, should produce much the same effect. 6. In both species reductions in mean erythrocytic volume took place at higher temperatures despite increases in cellular ion content which exceeded those of plasma. It is probable that reductions in cellular volume, which should favour branchial oxygen loading, were achieved by export of some as yet unidentified solute or solutes.

Acclimatization↗

Long-term measurement of volatile organic compounds in ambient air by canister-based one-week sampling method.

A canister-based 1 week sampling method using a mechanical flow controller and a 6 L fused-silica-lined canister was evaluated for the long-term measurement of 47 VOCs in ambient air at pptv (volume/volume) to ppbv levels by use of a three-stage preconcentation method followed by GC-MS analysis. The GC conditions were initially optimized for complete separations of several pptv-level VOCs (e.g. vinyl chloride, 1,3-butadiene, acrylonitrile, 1,2-dichloroethane and chloroform) in ambient air because the selected ions are easily interfered with by coexisting C4-, C5-hydrocarbons and analytes presented at ppbv levels. Thirty-four VOCs determined by the 1 week and 24 h sampling method in December 16-22 (2002) had concentrations of 6.0-15000 pptv per compound. Concentrations of 28 VOCs (including polar VOCs (e.g. methyl isobutyl ketone and butyl acetate)) obtained by the method were approximately equal to the mean values calculated from 24 h sampling (< +/- 10% deviation). Six VOCs that had low concentrations of 6.0-43 pptv showed more than +/- 10% deviation. Thirteen VOCs were not detected during the entire sampling period. The effect of relative humidity or ozone for the specific VOCs (e.g. MIBK, butyl acetate, vinyl chloride, 1,3-butadiene and styrene) was negligible.

Air Pollutants↗

Salt taste transduction occurs through an amiloride-sensitive sodium transport pathway.

An important early event in mammalian gustatory transduction with respect to sodium chloride has been found to be the passage of sodium ions through specific transport pathways in the apical region of the taste bud. The inward current caused by sodium chloride placed on the mucosal surface of an in vitro preparation of rat dorsal lingual epithelium can be substantially reduced by the blocker of sodium ion transport, amiloride. The data show (i) that amiloride is a specific blocker of the chorda tympani response to sodium chloride, but not to potassium chloride, (ii) that the sodium and potassium gustatory systems are largely independent at the peripheral level, and (iii) that the classical ion taste "receptor" is actually a specific transport pathway permitting the cation to enter the taste-bud cell and thereby to spread depolarizing current.

Amiloride↗

Early changes in alveolar fluid clearance by nitric oxide after endotoxin instillation in rats.

Alveolar fluid clearance may be inhibited and/or stimulated under pathologic conditions. We examined the early change of alveolar fluid clearance after endotoxin instillation in adult rats. We employed electron paramagnetic resonance nitric oxide (NO) trapping technique with iron complex with N,N-diethyldithiocarbamate as an NO trapping agent. We found that lung NO signals reached the highest magnitude by 6 hours after endotoxin instillation. NO production was accompanied by increases in lung cyclic guanosine monophosphate levels. Alveolar fluid clearance decreased significantly 6 hours after the administration of the endotoxin and increased further at 24 hours. These changes were shown to be related to the function of amiloride-sensitive sodium ion channels. Treatment with gadolinium chloride and aminoguanidine significantly decreased lung NO and cyclic guanosine monophosphate levels and completely ameliorated the decrease in alveolar fluid clearance. In addition, the increase in alveolar fluid clearance at 24 hours returned to normal levels after treatment with gadolinium chloride and aminoguanidine. We found immunoreactive inducible nitric oxide synthase to be abundantly expressed in the cytoplasm of alveolar macrophages. Our results suggest that alveolar endotoxin inhibits alveolar fluid clearance at 6 hours by NO. NO is produced via inducible NO synthase in endotoxin-stimulated alveolar macrophages and was also shown to increase alveolar fluid clearance at 24 hours.

Animals↗

High-conductance anion channels in embryonic chick osteogenic cells.

Patch-clamp measurements done on excised membrane patches obtained from 1-5 day cultured embryonic chick osteoblasts, osteocytes, and periosteal fibroblasts revealed the existence of a high-conductance anion channel: 371 +/- 63 pS when measured under symmetrical 158 mM Cl- conditions. The channel frequently displayed subconductance levels. The ion selectivity of the channel expressed as the (an)ion to chloride permeability ratio was as follows: Cl- (1.0) greater than methylsulfate- (0.71) greater than gluconate- (0.25) greater than glutamate- (0.17) greater than Na+ = K+ (0.10). In addition, the channel had a significant permeability for inorganic phosphate ions. The channel was found in about 1% of the cell-attached patches, which indicates that the channel is under the control of as yet unknown intracellular factors. Once activated by patch excision, the channel was voltage dependent and active at potentials close to 0 mV. At potentials outside the range of +/- 10 mV channel activity decreased. This process proceeded faster at increasing membrane potentials of either polarity. Returning to potentials close to 0 mV caused reopening of the channels within seconds if the preceding voltage step led to complete closure of the channels. Channel activity did not depend noticeably on intracellular and extracellular CA2+ ions. The channel is not unique to (chick) osteogenic cells but has been demonstrated in excised patches obtained from excitable and other nonexcitable cells. Although its presence in a wide variety of cell types suggests that the channel plays a general role in as yet unknown cell physiologic processes, the channel may also have specific functions in osteogenic cells, for example providing a pathway for phosphate ions during mineralization.

Animals↗

Semen characteristics of Muturu Bulls--Bos brachyceros.

Six mature Muturu Bulls were elecroejaculated once a week for nine weeks to study their semen quality and ejaculate characteristics. The semen volume was 1.8 ml+/-0.1, the sperm concentration 2.16x10(8)/ml+/-0.29, and the progressive sperm motility 36.2%+/-2.6. Morphologically normal sperm averaged 70.0%+/-3.1, primary abnormalities 13.4%+/-1.0 and secondary abnormalities 15.1%+/-2.3. Except in one bull, no measurable levels of fructose were observed. The contents of major cations and chloride ions in whole semen and seminal plasma were also determined.

Journal Article↗

Cellular differentiation is required for cAMP but not Ca(2+)-dependent Cl- secretion in colonic epithelial cells expressing high levels of cystic fibrosis transmembrane conductance regulator.

The gene responsible for cystic fibrosis (CF) has recently been cloned and sequenced. When transfected into CF epithelial cells, normal transcripts of this gene correct the underlying defect in CF, i.e. cAMP-dependent Cl- secretion is restored. Thus, the protein encoded by this gene, designated "cystic fibrosis transmembrane conductance regulator" (CFTR), somehow participates in the Cl- secretory response. In this paper we have correlated CFTR gene expression with cAMP and Ca(2+)-dependent Cl- secretion in unpolarized (parental) and polarized (Cl.19A) clones of the human colonic adenocarcinoma cell line HT-29. These cell lines were found to express equally high levels of CFTR mRNA at 4 days post-passage. In addition, protein expression (determined by immunoprecipitation) was also identical. The cAMP-generating agonist forskolin had little effect on 125I efflux from the unpolarized cells. In contrast, this agonist increased 125I efflux 3-fold in polarized cells. The lack of response in the unpolarized cells was not due to the inability of forskolin to raise cAMP levels. Neurotensin, a Ca(2+)-mobilizing agonist, stimulated 125I efflux from both cell lines. In the polarized cells, the magnitude of this response was attenuated at 8 days post-seeding. At this time, the undifferentiated line attained some cAMP responsiveness. This latter effect was paralleled by the appearance of monolayers within areas of the multicell layer. Cell-attached patch-clamp recording from apical membrane patches of polarized cells revealed the presence of a forskolin-stimulated 8-pS Cl- channel; no channel activity was observed in forskolin-stimulated unpolarized cells. Ca(2+)-activated Cl- channels were found in both cell lines. In agreement with the 125I efflux data, the single-channel activation response to [Ca2+]i was smaller in the polarized cell line. From these studies, we can conclude that CFTR expression, measured both at the mRNA and protein level, does not correlate with the colonocyte's ability to secrete chloride ions in response to a cAMP-generating agonist. Cyclic AMP-dependent Cl- secretion requires cellular polarization; specifically, the delineation of an apical membrane. Differences in the cellular location of CFTR during differentiation are likely to explain our results. In contrast, Ca(2+)-stimulated Cl- secretion occurred independently of cellular polarization but was reduced when the cells formed tight junctions.

Adenocarcinoma↗