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Results for “Chloride Ion Level”

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PubMed2005

Molecular basis of the effects of chloride ion on the acid-base catalyst in the mechanism of pancreatic alpha-amylase.

Pig pancreatic alpha-amylase (PPA), an enzyme belonging to the alpha-amylase family, is involved in the degradation of starch. Like some other members of this family, PPA requires chloride to reach maximum activity levels. To further explain the mechanism of chloride activation, a crystal of wild-type PPA soaked with maltopentaose using a chloride-free buffer was analyzed by X-ray crystallography. A conspicuous reorientation of the acid/base catalyst Glu233 residue was found to occur. The structural results, along with kinetic data, show that the acid/base catalyst is maintained in the active site, in an optimum position, pointing toward the scissile bond-atom, due to the presence of chloride ions. The present study therefore explains the mechanism of PPA activation by chloride ions.

Animals↗

PubMed2006

Endothelin ETA receptor blockade with darusentan increases sodium and potassium excretion in aging rats.

This study investigated whether intrarenal endothelin-1(ET-1) contributes to sodium excretion in aged rats. Metabolic function studies were performed in male Wistar rats (3 and 24 months) treated with placebo or the orally active ET(A) receptor antagonist darusentan (20 mg/kg/d) for 4 weeks. Mean arterial pressure was measured using an intra-arterial catheter. Electrolytes, aldosterone levels, renin activity, and angiotensin converting enzyme activity were determined in plasma, and mRNA expression of epithelial sodium channel (ENaC) and Na(+), K(+)-ATPase subunits was measured in the renal cortex and medulla. Aging was associated with a marked decrease in urinary excretion of sodium, chloride, and potassium (all P < 0.001) as well as renin activity (P < 0.05), but had no significant effect on gene expression of ENaC or Na(+), K(+)-ATPase subunits. In aged rats, darusentan treatment increased ion excretion (P < 0.05), reduced cortical gene expression of alphaENaC and alpha(1)-Na(+), K(+)-ATPase (both P < 0.05), and increased plasma aldosterone levels (P < 0.01). These data demonstrate a decrease of sodium and potassium excretion in aged rats, changes that are partly sensitive to ETA receptor blockade. Treatment with darusentan also reduced cortical expression of alphaENaC and alpha(1)-Na(+), K(+)-ATPase and increased plasma aldosterone levels independently of blood pressure, electrolytes, renin activity, or angiotensin converting enzyme activity. These findings may provide new pathogenetic links between aging and sodium sensitivity.

Aging↗

PubMed2000

Burst properties of a supergated double-barrelled chloride ion channel.

The chloride selective channel from Torpedo electroplax, ClC-0, is the prototype of a large gene family of chloride channels that behave as functional dimers, with channel currents exhibiting two non-zero conductance levels. Each pore has the same conductance and is controlled by a subgate, and these have seemingly identical fast gating kinetics. However, in addition to the two subgates there is a single slower 'supergate' which simultaneously affects both channels. In the present paper, we consider a six state Markov model that is compatible with these observations and develop approximations as well as exact results for relevant properties of groupings of openings, known as bursts. Calculations with kinetic parameter values typical of ClC-0 suggest that even simple approximations can be quite accurate. Small deviations from the assumption of independence within the model lead to marked changes in certain predicted burst properties. This suggests that analysis of these properties may be helpful in assessing independence/non-independence of gating in this type of channel. Based on simulations of models of both independent and non-independent gating, tests using binomial distributions can lead to false conclusions in each situation. This is made more problematic by the difficulty of selecting an appropriate critical time in defining a burst empirically.

Animals↗

PubMed1988

The magnesium, calcium, sodium, potassium and chloride contents of the term human placenta.

The ion content of the human term placenta was determined. When ordered decreasingly according to their placental content, the series of ions was: Na greater than Cl greater than K greater than Ca greater than Mg. These levels, plotted as a function of the tissue dry weight, showed an exponential distribution. Using Cl as an extracellular marker, Na and K cellular concentrations were evaluated. The equilibrium potentials derived from these values were very different from the measured syncytial membrane potential or from the value usually recorded in non-innervated tissues.

Calcium↗

PubMed1989

Mechanism of calcium ionophore stimulated Cl secretion from frog skin glands.

The aim of the present study was to investigate the mechanism by which the calcium ionophore A23187 stimulates Cl and water secretion from exocrine glands in the frog skin. The Cl secretion was visualized as changes in short-circuit current (SCC) in skins where the Na absorption was blocked by amiloride applied to the apical membrane. Measurements of A23187 stimulated ion fluxes showed that the ionophore induced a net secretion of Cl, Na and K. The active Cl secretion was enhanced more than the Na and K secretion, resulting in a net secretion of negative ions which closely resembled the A23187-stimulated SCC. The effect of A23187 was abolished in skins pretreated with indomethacin, implying the involvement of prostaglandins in the response. Furthermore, the effect of A23187 was inhibited in the presence of quinacrine, indicating that the activation of the cyclooxygenase pathway is dependent on phospholipase A2 activity. In addition, the A23187, but not the arachidonic acid stimulated Cl secretion was abolished in the presence of trifluoperazine, suggesting that the effect of the ionophore may be mediated via a Ca2+ -calmodulin-dependent step located before the activation of the cyclooxygenase. The net water flow and the Cl secretion were measured simultaneously under the conditions outlined above. The stimulation, inhibition, and time-course of the water secretion were similar to the changes observed for the Cl secretion. The A23187 stimulated Cl secretion was enhanced by the phosphodiesterase inhibitor, theophyllin, indicating that the effect of A23187 was caused by an increase in the intracellular cAMP level in the gland cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Amiloride↗

PubMed1976

Gas-liquid chromatographic headspace method for vinyl chloride in vinegars and alcoholic beverages.

Vinyl chloride (VC) is determined in vinegars and alcoholic beverages by gas-liquid chromatographic headspace analysis. The lower limit of detection is 10 ppb and confirmation by gas chromatography-mass spectrometry, single ion monitoring at m/e 62, is possible at this level. Comparison of the headspace and the direct injection methods for the determination of VC in vinegars and alcoholic beverages showed that the results obtained by the 2 methods were not significantly different (P greater than 0.05).

Acetates↗

PubMed1986

Mucosal adenosine stimulates chloride secretion in canine tracheal epithelium.

Adenosine is a local regulator of a variety of physiological functions in many tissues and has been observed to stimulate secretion in several Cl-secreting epithelia. In canine tracheal epithelium we found that adenosine stimulates Cl secretion from both the mucosal and submucosal surfaces. Addition of adenosine, or its analogue 2-chloroadenosine, to the mucosal surface potently stimulated Cl secretion with no effect on the rate of Na absorption. Stimulation resulted from an interaction of adenosine with adenosine receptors, because it was blocked by the adenosine receptor blocker, 8-phenyltheophylline. The adenosine receptor was a stimulatory receptor as judged by the rank-order potency of adenosine and its analogues and by the increase in cellular adenosine 3',5'-cyclic monophosphate levels produced by 2-chloroadenosine. Adenosine also stimulated Cl secretion when it was added to the submucosal surface, although the maximal increase in secretion was less and it was much less potent. Part, but not all, of the lower potency of submucosal adenosine resulted from submucosal uptake and metabolism of the drug. The observation that mucosal 8-phenyltheophylline blocked the effect of submucosal 2-chloroadenosine, whereas submucosal 8-phenyltheophylline did not prevent a response to mucosal or submucosal 2-chloroadenosine, suggests that adenosine receptors are located on the mucosal surface. Thus submucosal adenosine may stimulate secretion by crossing the epithelium and interacting with receptors located on the mucosal surface. Because adenosine can be released from mast cells located in the airway lumen in response to inhaled material, and because adenosine stimulated secretion from the mucosal surface, it may be in a unique position to control the epithelium on a regional level.

2-Chloroadenosine↗

PubMed1985

Kinin effects on electrogenic ion transport in primary cultures of pig renal papillary collecting tubule cells.

Confluent monolayers of pig renal papillary collecting tubule (RPCT) cells were formed on Millipore filters coated with collagen. They were clamped in Ussing-type chambers and used to measure short-circuit current (SCC). The monolayers had low potentials (0.1 mV) with the basolateral side positive. Small inward currents flowed under short-circuit conditions. Increases in SCC were obtained following addition of a number of agents. Receptors associated with SCC changes were disposed as follows: for kinins (e.g., lysyl-bradykinin) they were present on both sides of the tissue, while those for arginine vasopressin and norepinephrine were present on the basolateral side only. Epithelia responded to PGE2 added to the apical or basolateral face of the tissue; application to one side prevented the response from the contralateral side. The tissues also responded to forskolin, an activator of adenylate cyclase, with a sustained inward current that was sensitive to furosemide. Similar sustained inward currents were recorded following exposure to 8-bromoadenosine-3',5'-cyclic monophosphate (BrcAMP). Responses to kinins were attenuated by inhibition of fatty acid cyclooxygenase with either indomethacin or piroxicam or by replacing chloride with impermeant ions. If the SCC was first increased with forskolin, BrcAMP, or norepinephrine, the kinin effects on SCC were either abolished or reversed. It is concluded that kinin can cause chloride secretion in RPCT monolayers, possibly via a prostaglandin or a prostaglandin-adenylate cyclase mechanism. Secondary effects of kinin, exposed by first raising tissue cAMP levels, are not precluded.

8-Bromo Cyclic Adenosine Monophosphate↗

PubMed1967

Relative ion permeabilities in the crayfish giant axon determined from rapid external ion changes.

The changes in membrane potential of isolated, single crayfish giant axons following rapid shifts in external ion concentrations have been studied. At normal resting potential the immediate change in membrane potential after a variation in external potassium concentration is quite marked compared to the effect of an equivalent chloride change. If the membrane is depolarized by a maintained potassium elevation, the immediate potential change due to a chloride variation becomes comparable to that of an equivalent potassium change. There is no appreciable effect on membrane potential when external sodium is varied, at normal or at a depolarized membrane potential. Starting from the constant field equation, expressions for the permeability ratios P(Cl)/P(K), P(Na)/P(K), and for intracellular potassium and chloride concentrations are derived. At normal resting membrane potential, P(Cl)/P(K) is 0.13 but at a membrane potential of -53 mv (external potassium level increased about five times) it is 0.85. The intracellular concentrations of potassium and chloride are estimated to be 233 and 34 mM, respectively, and it is pointed out that this is not compatible with ions distributed in a Nernst equilibrium across the membrane. It is also stressed that the information given by a plot of membrane potential vs. the logarithm of external potassium concentrations is very limited and rests upon several important assumptions.

Animals↗

PubMed1994

Effects of [(N-alkyl-1,3-dihydro-1-oxoisoindolin-5-yl)oxy]alkanoic acids on chloride transport in primary astroglial cultures.

It has been demonstrated that agents which inhibit chloride influx and, therefore, lower intracellular chloride levels in the astrocyte, a major cell type in the cerebral gray matter, inhibit astrocytic swelling in vitro and in vivo. Herein, we report additional examples of a series of [(N-alkyl-1,3-dihydro-1-oxoisoindolin-5-yl)oxy]alkanoic acids and their effects upon ion transport in primary rat astrocyte cultures. The 4-chloro-substituted 1-oxoisoindolines demonstrated superior astrocytic chloride influx inhibitory activity as compared to the 6-chloro and non-chlorinated analogs. The four-carbon acid side chain derivatives were more active than the three- and two-carbon analogs. The pharmacological profile of these compounds was examined with respect to inhibition of the Cl(-)-Cl-/Cl(-)-HCO3- anion exchanger and Na(+)-K(+)-2Cl- cotransport mechanisms in glia, and the compounds were found to exhibit a similar profile to that of furosemide by inhibiting both transporters.

Animals↗

PubMed1997

Regulation of ion transport by histamine in mouse cecum.

Histamine levels are elevated in inflammatory bowel disease. We investigated the mechanism by which histamine affects electrolyte transport in the mouse cecum. Using the Ussing-chamber voltage clamp technique, histamine was found to cause a transient concentration-dependent increase in short-circuit current, a measure of total ion transport across the epithelial tissue. This increase was not affected by amiloride pretreatment, but was significantly inhibited by bumetanide and completely inhibited when chloride was substituted in the bathing buffer by gluconate. A histamine-induced increase in short-circuit current was also significantly reduced by inhibitors of the cyclooxygenase pathway indicating the involvement of prostaglandin E2 in its action. Prostaglandin E2 levels were increased in histamine treated tissue and this increase was reversed by indomethacin. These data suggest that histamine causes its effect on mouse cecum largely through increasing arachidonic acid metabolism resulting in increased levels of prostaglandins which in turn increase Cl- secretion in the epithelial cells.

Animals↗

PubMed2005

[Comparative study on the influence of arginine hydrochloride and arginine acetate on the immune function and acid-base balance in rabbits with severe burns].

OBJECTIVE: To investigate the influence of arginine hydrochloride and arginine acetate on the immune function and acid-base balance in rabbits with severe burns. METHODS: One hundred and ten flap-eared rabbits were used in the study, in which 8 served as normal control, while the rest were inflicted with 30% TBSA full thickness burn. All the rabbits were divided into 10 groups, i.e. normal control (C, n = 14), burn control (B, n = 14, with intravenous infusion of Ringer's solution), 0.3 g/kg arginine hydrochloride (AH, n = 12), 0.3 g/kg arginine acetate (AA, n = 10), 0.6 g/kg AH (n = 10), and 0.6g/kg AA (n = 10) groups, 1.2 g/kg AH (n = 10), 1.2 g/kg AA (n = 10), 2.4 g/kg AA (n = 14) and 2.4 g/kg AH (n = 12) groups. AA and AH in different doses were fed to rabbits in corresponding groups 2 times a day for 7 days. The changes in the immune function, acid-base balance, chloride ion metabolism, and mortality were determined. RESULTS: Disorder in immune system was found after severe burns, with enhanced immune function at the beginning and weakening afterwards. The lymphocytic transformation rate, the CD4/CD8 ratio, the phagocytosis rate and the chemotactic index of white blood cells on 7 post burn day (PBD) were obviously lower in B group compared with C group (P < 0.05 or 0.01). These indices were obviously higher in 1.2, 2.4 g/kg AA and AH groups than those in B group on 7 PBD (P < 0.05 or 0.01). There was no difference in improvement of immune functions between 0.3, 0.6g/kg AH, AA group and B group. The values of blood pH, base excess (BE), buffer base (BB), HCO(3)(-) level in AH group were significantly lower than those in C group on 7 PBD (P < 0.05 or 0.01), while there were no obvious changes in AA group, they were obviously higher than those in AH group (P < 0.05 or 0.01). The contents of chloride ion in but 2.4 g/kg AH group during 5 to 7 PBD were obviously higher than those in C group and 2.4 g/kg AA group (P < 0.05 or 0.01), while no difference was found between 2.4 g/kg AA and C groups. The mortality in B group was obviously higher than that in 0.3, 0.6, 1.2 g/kg AH and AA groups (P < 0.05 or 0.01), but significantly lower than that in 2.4 g/kg AA and AH groups (P < 0.05). CONCLUSION: Disorders in immune functions were observed in severely burned rabbits. Administration of arginine acetate as well as arginine hydrochloride could enhance the immune function, but arginine acetate seemed to be safer than arginine hydrochloride. Excessive dosage should be avoided to prevent a rise of the mortality.

Acetates↗

PubMed2001

[Mechanisms of action of hypersodium medium on contractile activity of isolated rat heart].

Despite the high efficiency of elevated concentrations of sodium ions during myocardial ischemia and calcium paradox, the molecular mechanism of action of hypersodium media on heart contractions remains unknown. The purpose of the investigation was to study mechanisms by which raised concentrations of sodium ions alter cardiac contractility. Subsequent to initially developed reduced pressure in the left ventricle, elevated concentrations of sodium ions (200 mM instead of 140 mM NaCl, 3 mM KCl) produced an increased force of contractions of about 50%. The first stage of decrease in developed pressure did not relate to elevated tonicity of extracellular ionic millieu because lithium chloride (60 mM) did not produce the same effect. This action of elevated concentrations of sodium ions has been shown to be independent of blockers of ion-transporting systems (caffeine, verapamile, ethmozine, HMA or lidocaine). Raising the contractions by elevating the concentration of sodium ions (second stage) has been shown to be susceptible to sodium channel blockers (6-IA, benzamil, of phenamil) and to caffeine. Decreasing of potassium concentration (from 3 mM to 1-2 mM amplified, and increasing of K+ level (from 3 mM to 6 mM) attenuated the positive inotropic action of the elevated concentration of sodium ions. The positive inotropic effect due to elevated concentrations of sodium ions remains even after heart arrest by high concentrations of verapamile (2 mcM). Lithium chloride (60 mM) failed to elevate left ventricle developed pressure which was raised by elevated concentrations of sodium ions. These data suggest that the elevated concentration of sodium ions could effect Na+/Ca2+ exchange and provoke Ca2+ release from sarcoplasmic reticulum by changing the sodium gradient and resulting in Ca2+ entry via Na+/Ca2+ exchange. These observations are consistent with the hypothesis of Leblanc N., Hume J.R. (1990) regarding sodium-induced calcium ion release from sarcoplasmic reticulum.

Animals↗

PubMed1993

Detection of a GC/MS artifact peak as methamphetamine.

Recently, certain laboratories reported the presence of methamphetamine in several negative urine specimens. We have demonstrated an artifact peak, by SIM GC/MS, in negative urine specimens, that frequently matches the retention time and identity ion ratio criteria for methamphetamine. This peak resulted from the presence of high levels of pseudoephedrine (PS) or ephedrine (EP) and was produced after derivatization with 4-carbethoxyhexafluorobutyryl chloride (CB), heptafluorobutyric anhydride (HFB), and N-trifluoroacetyl-l-prolyl chloride (TFAP). Use of N-methyl trideuterated PS and two deuterated EP compounds in spiked samples provided additional proof that PS and EP can produce the artifact peak. The above results were achieved using a GC injection port temperature of 300 degrees C and low split and isothermal conditions. Thermal transformation in the injector is involved because lowering and raising the injector temperature results in the disappearance and subsequent reappearance of the artifact peak. Proof that the artifact peak is actually methamphetamine was provided by full-scan GC/MS data of the artifact peak produced after use of all three derivatizing reagents. GC/MS analysis has demonstrated that urine (65 specimens) with concentrations of PS or EP ranging from 100,000 to 1,100,000 ng/mL will test negative for methamphetamine, while the same specimens will trigger positive results by radioimmunoassay and the Emit monoclonal assay. Full-scan GC/MS of the CB derivative for PS and EP reveals what appears to be both mono- and diderivatized products. SIM analysis can differentiate between PS and EP in urine specimens because the relative amounts of mono- and diderivatized products are very different for PS than for EP.(ABSTRACT TRUNCATED AT 250 WORDS)

Artifacts↗

PubMed1977

Oxygen uptake of canine whole body and hind limb with hypocapnic alkalosis.

The effect of hypocapnic alkalosis induced by hyperventilation on whole-body and hind-limb oxygen uptake (VO2) was studied in dogs anesthetized with pentobarbital. In the intact dog with a self-perfused hind limb, increasing pHa from 7.41 to 7.58 increased whole-body VO2 8% and decreased hind-limb VO2 6%. Isolated hind limbs perfused with heparinized whole blood had similar decreases in VO2 with increases in arterial blood pH (pHa). However, isolated hind limbs perfused with whole blood containing citrate, phosphate, and dextrose (CPD) showed muscle twitches, had larger VO2 values at identical pHa's, and had an increase in VO2 with increase in pHa. These changes with a CPD perfusate were associated with low levels of ionized calcium (less than 0.5 mEq/1), disappeared when calcium ion spontaneously increased to 1.0 mEq/1, and could be prevented or abolished by the addition of calcium chloride, dantrolene, d-tubocurarine, or succinylcholine. These results are in accord with the findings of others regarding an increase in whole-body VO2 with hypocapnic alkalosis, but do not support a contributory role of skeletal muscle to the overall increase.

Alkalosis↗

PubMed1997

A1 adenosine receptors potently regulate heart rate in mammalian embryos.

A1 adenosine receptors (A1ARs) have been recently shown to be expressed in rodent embryonic hearts at very early stages of development. To determine the functional significance of fetal cardiac A1AR expression during embryogenesis, murine fetal heart preparations were studied between postconceptual days 9 and 12. Dose-response curves generated using a variety of adenosine agonists revealed that A1AR activation potently regulated fetal heart rates. The A1AR agonist, N6-cyclopentyladenosine, inhibited heart rates in a dose-dependent manner (half-maximal effective concentration = 3.6 x 10(-8) M) and stopped fetal cardiac contractions in 63% of preparations. In contrast, A2a and A2b receptor activation did not alter heart rates, and activation of A3 receptors produced modest declines in heart rates. Endogenous adenosine also acted tonically to suppress fetal heart rates, as demonstrated by the A1AR antagonist 1,3-dipropyl-8-cyclopentylxanthine, increasing heart rates, whereas the adenosine reuptake blocker dipyridamole lowered fetal heart rates. Pertussis toxin treatment blocked A1AR action, showing that A1AR action was G protein mediated. Using drugs that alter cAMP levels and ion channel action, we were able to show that A1AR action involves events mediated by cAMP, ATP-dependent K, L-type calcium, sodium, and chloride channels, and the pacemaker current. These data show that adenosine and A1ARs potently regulate mammalian heart rates via multiple effector systems at very early stages of prenatal development.

Adenosine↗

PubMed1977

Blood respiratory properties of rainbow trout (Salmo gairdneri) kept in water of high CO2 tension.

1. Blood O2 transport and acid-base balance were studied at 20 degrees C in rainbow trout (Salmo gairdneri) which had been kept in water of high CO2 content (15 mmHg) for at least a week. Also the blood gas chemistry of fish rapidly entering or leaving the hypercapnic environment was studied. 2. Fish entering high CO2 water suffered a sharp decrease in blood pH which significantly reduced O2 transport by the blood, but after a few hours considerable compensation was achieved. 3. After at least a week in high CO2 water, trout showed elevated plasma bicarbonate and PCO2 levels, and a decrease in plasma chloride, while pH was about 0 - 1 pH unit below the level for control fish. Oxygen transport by the blood was marginally reduced. 4. Hypercapnic fish rapidly entering fresh water showed a sharp increase in blood pH and a decrease in blood PO2. These parameters regained normal values after a few hours but plasma bicarbonate and chloride levels took much longer to regain control concentrations. 5. Acid-base balance in hypercapnic fish is discussed with particular reference to the role of the branchial ion exchanges.

Adaptation, Physiological↗

PubMed1964

PRODIGIOSIN-PRODUCING BACTERIA FROM MARINE SOURCES.

Two aerobic, gramnegative, red-pigmented, rod-shaped bacteria were compared morphologically and physiologically with Serratia species, which they resembled superficially. The pigment produced by the marine isolates was shown to be similar to prodigiosin, the red pigment of S. marcescens. The isolates had a single polar flagellum, were oxidative, and did not produce acetoin from glucose or reduce nitrates, which made them distinct from both S. marcescens and S. marinorubra. The latter conformed well to the descriptions of S. marcescens in Bergey's Manual. The marine isolates displayed an absolute growth requirement for sea water or its equivalent. The growth requirement for sea water was replaced by sea-water levels of sodium, potassium, and magnesium chloride. Pigment was produced only when this salt mixture was further supplemented with calcium chloride. Neither sea water nor a high salt level was required for growth or prodigiosin synthesis by the Serratia species examined.

Calcium↗