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PubMed1979

The role of cell-fixed calcium in histamine release by compound 48/80.

1. Histamine release by compound 48/80 was substantially reduced in a time-dependent manner (maximum at 30 min) by pre-incubating mast cells in calcium-free medium at 37 degrees C but not at 2 degrees C. This effect was optimal at pH 7.0 to 7.5. 2. The re-introduction of calcium (0.1 to 3 mmol/l) restored histamine release to the control value; this effect was independent of temperature. 3. Strontium (1 to 30 mmol/l) partially reversed the effect of calcium deprivation but the same concentrations of barium and magnesium depressed histamine release even further. Magnesium (3 to 15 mmol/l) antagonized the effect of calcium replacement. 4. Results suggest that the level of cell-fixed calcium involved in compound 48/80-induced histamine release may be controlled by the combination of rapid passive influx and slow active efflux.

Animals↗
PubMed1976

Pharmacology of dihydroxy-dibutylether, a specific choleretic drug.

The choleretic and the general pharmacological properties of dihydroxy-dibutyl ether (Discinil) were investigated in several animal species. Discinil (DHBE) increased the bile flow in conscious rats and dogs, after both oral and i.v. administration. A choleretic effect was also observed after i.v. injection into anaesthetized rats and guinea pigs. A dose-response relationship was always obtained, the threshold dose being 25--100 mg/kg. No evidence of tachyphylaxis was observed in rats after repeated treatments. The bile hyperflow was generally accompanied by an increased excretion of the total dry residue in guinea pigs and dogs. The choleretic effect in rats was still present after pretreatment with either DL-ethionine (causing parenchymal liver damage) or atropine (blocking the cholinergic control of bile production). At low doses (25--100 mg/kg i.v.) eliciting a definite choleretic response, DHBE did not show spasmogenic and spasmolytic effects in vivo on the smooth muscles of the gallbladder of guinea pigs and dogs, neither on the stomach and intestine of mice and dogs; while it constricted the pylorus sphincter of rats. At larger doses (200--400 mg/kg i.v.) the compound showed a mild relaxing activity on Oddi's sphincter of guinea pigs and a weak spasmogenic activity either on gall bladder or on small intestine. In vitro, it caused an unspecific antagonism against the spasm induced by acetylcholine, barium chloride, histamine, 5-hydroxytryptamine and norepinephrine. In anaesthetized rats, rabbits and dogs, DHBE caused a moderate and short-lasting hypotension, and tachycardia. The threshold doses for these effects were 2--4 times superior to those being choleretic. In conscious dogs, the compound was slightly hypertensive. DHBE did not provoke important respiratory and ECG changes, neither showed diuretic nor antiphlogistic effects.

Administration, Oral↗
PubMed1996

Synthesis of Tris(1,2-dimethoxyethane-O,O')barium Bis(2,2,5,5-tetramethyl-2,5-disilaphospholanide) and the Monomer-Dimer Equilibrium in Toluene Solution.

(1,2-Dimethoxyethane-O,O')lithium phosphanide (dme)LiPH(2) reacts with 1,2-bis(chloro-dimethylsilyl)ethane to give 2,2,5,5-tetramethyl-2,5-disilaphospholane, 1, as well as 1,1,4,4-tetramethyl-1,4-bis(2,2,5,5-tetramethyl-2,5-disilaphospholanyl)-1,4-disilabutane, 2 (P(2)Si(6)C(18)H(48), space group P&onemacr;, a = 943.3(2) pm, b = 1278.3(3) pm, c = 1413.3(2) pm, alpha = 72.45(1) degrees, beta = 78.13(1) degrees, gamma = 70.83(1) degrees, d = 1.081 g cm(-)(3), Z = 2, wR2 = 0.1553 at 6548 F(2) values). The reaction of 2,2,5,5-tetramethyl-2,5-disilaphospholane 1 and barium bis[bis(trimethylsilyl)amide] in 1,2-dimethoxyethane yields nearly quantitatively tris(1,2-dimethoxyethane-O,O')barium bis(2,2,5,5-tetramethyl-2,5-disilaphospholanide), 3A, which crystallizes in the monoclinic space group C2/c (BaP(2)Si(4)O(6)C(24)H(62), a = 2152.3(1) pm, b = 1381.5(1) pm, c = 1459.7(1) pm, beta = 113.73(1) degrees, d(calc) = 1.268 g cm(-)(3), Z = 4, wR2 = 0.0989 at 5220 F(2) values). Due to the high coordination number of eight of the barium center, rather long Ba-P distances of 333 pm are observed. With loss of the complexating ether solvent this compound forms a dimer 3B of the type R(dme)Ba(&mgr;-R)(3)Ba(dme)(2) in toluene or benzene solution as can be proven by (31)P{(1)H}-NMR spectroscopy ((2)J(P-P) = 6.7 Hz) and by X-ray structure analysis (Ba(2)P(4)Si(8)O(6)C(48)H(106), space group P2(1)/n, a = 1256.3(2) pm, b = 2000.0(3) pm, c = 2986.9(2) pm, beta = 98.929(9) degrees, d(calc) = 1.257 g cm(-)(3), Z = 4, wR2 = 0.1334 at 11580 F(2) values). The Ba-P bond lengths vary between 318 and 338 pm.

Journal Article↗
PubMed1993

Blockade by calmodulin inhibitors of Ca2+ channels in smooth muscle from rat vas deferens.

1. Effects of three compounds which are used as calmodulin inhibitors (trifluoperazine, W-7 and calmidazolium) on Ca2+ channels were investigated in smooth muscle from rat vas deferens. 2. All three calmodulin inhibitors relaxed the smooth muscle precontracted by a high concentration of KCl (63.7 mM). The order of potency for the relaxation was trifluoperazine > W-7 > calmidazolium. 3. In binding studies using a microsomal fraction of vas deferens, all these calmodulin inhibitors displaced specific [3H]-nimodipine binding. Trifluoperazine and W-7 inhibited the binding at concentrations that relaxed the smooth muscle whereas calmidazolium inhibited at concentrations much lower than those necessary for muscle relaxation. 4. Ba2+ current flowing through voltage-gated Ca2+ channels was measured under whole-cell voltage-clamp conditions in isolated smooth muscle cells. The Ba2+ current was suppressed by the three calmodulin inhibitors in the concentration-range where inhibition of [3H]-nimodipine binding was observed. Neither voltage-dependence nor the inactivation time course of Ba2+ current were affected by these compounds. 5. The results suggest that the calmodulin inhibitors directly block Ca2+ channels in the smooth muscle cells. The channel inhibition by trifluoperazine and W-7, but perhaps not that by calmidazolium, may be responsible for the muscle relaxation observed with these compounds.

Animals↗
PubMed1999

Redox modulation of intracellular free calcium concentration in thyroid FRTL-5 cells: evidence for an enhanced extrusion of calcium.

Redox modulation is involved in the regulation of the intracellular free calcium concentration ([Ca2+]i) in several cell types. In thyroid cells, including thyroid FRTL-5 cells, changes in [Ca2+]i regulate important functions. In the present study we investigated the effects of the oxidizing compounds thimerosal and t-butyl hydroperoxide on [Ca2+]i in thyroid FRTL-5 cells. Thimerosal mobilized sequestered calcium, and evoked modest store-dependent calcium entry. Both compounds potently attenuated the increase in [Ca2+]i when store-operated calcium entry was evoked with thapsigargin. The entry of barium was not attenuated. Experiments performed with high extracellular pH, in sodium-free buffer and in the presence of vanadate suggested that thimerosal decreased [Ca2+]i by activating a calcium extrusion mechanism, probably a plasma membrane Ca2+-ATPase. All the observed effects were abrogated by the reducing agent beta-mercaptoethanol. The mechanism of action was apparently mediated via activation of protein kinase C, as thimerosal potently stimulated binding of [3H]phorbol 12, 13-dibutyrate, and was without effect on store-operated calcium entry in cells treated with staurosporine or in cells with down-regulated protein kinase C. Thimerosal did not depolarize the membrane potential, as evaluated using patch-clamp in the whole-cell mode. In immunoprecipitates obtained with an antibody against plasma membrane Ca2+-ATPase, we observed several phosphorylated bands in cells stimulated with thimerosal. In conclusion, we have shown that thimerosal attenuates an increase in [Ca2+]i, probably by activating a plasma membrane Ca2+-ATPase.

Animals↗
PubMed1991

Effects of inorganic potassium channel blockers on calcium requirement of transmission in a sympathetic ganglion.

The effects of the alkali metal ions cesium (Cs+) and rubidium (Rb+) and alkaline earth metal ions barium (Ba2+) and strontium (Sr2+) on ganglionic transmission in various calcium (Ca2+) concentrations were investigated in rat isolated superior cervical ganglia. Cesium (1 and 2 mM) moderately supported transmission in low Ca2+ and potentiated the compound action potential (CAP) at high Ca2+ concentration. Higher concentrations of Cs+ caused depression of CAP especially at lower Ca2+ concentration. Cesium (1-4 mM) induced large spontaneous rhythmic spikes or burst of spikes. At 4 mM, Rb+ potentiated CAP at all Ca2+ concentrations. As with Cs+, higher concentrations of Rb+ inhibited CAP except at large Ca2+ concentrations. Barium (1-6 mM) effectively enhanced transmission at all Ca2+ concentrations. Strontium enhanced transmission only at very low Ca2+ concentrations. No enhancement was seen with Sr2+ in the presence of normal or higher Ca2+. The results indicate that Cs+ and Rb+ may antagonize Ca2+ effects at release sites while allowing more Ca2+ influx into the nerve terminal as a result of K+ channel blockade. Barium and to a lesser extent Sr2+ may substitute for Ca2+ in the process of transmitter release in the superior cervical ganglia of rats.

Action Potentials↗
PubMed2003

BaP4Te2--a ternary telluride with P-Te bonds and a structural fragment of black phosphorus.

The new telluride BaP(4)Te(2) was synthesized in form of gleaming black needles by heating stochiometric mixtures of the elements to 475 degrees C for 100 h. The crystal structure was determined by single-crystal Xray methods. BaP(4)Te(2) crystallizes orthorhombically, space group Pnma with a=16.486(8), b=6.484(2), c=7.076(4) A, and Z=4. A main feature of the so far unknown crystal structure type are P(4)Te(2) chains that consist of condensed six-membered rings of phosphorus. These strands are equivalent to a structural fragment of black phosphorus, in which each of the lateral atoms is connected to a tellurium atom. The chains running along [0 1 0] are separated from each other by barium atoms, that is, linked through Ba-Te and Ba-P bonds. BaP(4)Te(2) is an electron precise compound according to the Zintl concept, and the formula can be split ionically as follows: BaP(4)Te(2) identical with Ba(2+)(P(0))(4)(Te(-))(2). The remarkable Te-P bonds have been analyzed by electronic structure calculations using the electron localization function (ELF) and the crystal orbital Hamiltonian population (COHP) methods.

Journal Article↗
PubMed1992

The inward rectifier potassium conductance in rat basophilic leukemia cells.

Whole-cell recordings were made from rat basophilic leukemia cells. The properties of the cells in the potential range negative to -20 mV could be accounted for by two potassium conductances, a leakage conductance (0.54 +/- 0.01 nS, mean +/- s.e.m., n = 6) and an inward rectifier conductance. The inward rectifier conductance activated at a potential close to EK and had a maximal value of 2.7 +/- 0.22 nS (n = 6). Cesium (2 mM, n = 6) decreased the inward current at every potential. Strontium (10 mM, n = 7) and rubidium (2 mM, n = 3) had a similar effect, but they also increased the slope conductance between -63 and -103 mV. Barium (1-100 microM) blocked selectively the inward rectifying current without affecting the leakage current; the effect was use-, voltage-, and temperature-dependent. TEA decreased the current; the concentration giving 50% inhibition was 37.5 mM. The current was unaffected by phorbol esters as well as several hormones and transmitters that were tested.

Animals↗
PubMed1999

Double-contrast magnetic resonance examination of ulcerative colitis.

The aim of our work was to propose a double-contrast magnetic resonance examination (DCMRE) in the follow-up of ulcerative colitis (UC), comparing this new technique with X-ray double-contrast barium enema (DCBE). After preparation with colon-cleansing regimen used for DCBE, six UC patients and six control subjects underwent a 1.5-T examination: supine position, coronal and axial fat-spectral-saturation breath-hold gradient-echo T1-weighted sequences after intravenous hypotonization and 1500-2000 cc air insufflation. Without evacuating the primarily insufflated air, the same images were acquired after endorectal administration of negative superparamagnetic contrast agent (600 cc) and intravenous administration of positive paramagnetic contrast agent (0.2 mmol/kg). All patients had undergone DCBE in the four preceding weeks. We found significant increase in wall thickness of UC affected vs apparently unaffected segments (p = 0.0425) and vs CG (p = 0.0447), significant increase in enhancement percent of UC affected vs apparently unaffected segments (p = 0.0161) and vs CG (p = 0.0185), and no significant difference for enhancement percent of UC unaffected segments vs CG. DCMRE and DCBE localized the UC extension at the same sites in all patients. Double-contrast MR examination time was 20-30 min. This new method could be used in follow-up of UC patients.

Barium Sulfate↗
PubMed1996

Zinc acetate and lyophilized aloe barbadensis as vaginal contraceptive.

Twenty samples of fresh ejaculate, donated by healthy volunteers ranging in age from 20-30 years, were obtained from the Center for Fertility & Cryobiology, University of Missouri, Columbia, Missouri. Average semen volume was 2.49 ml; average sperm motility was 71.32%; and average sperm density was 113.71 x 10(6) /ml. Testing for spermicidal effectiveness of a 1% concentration of zinc acetate, zinc sulfate, zinc chloride, and zinc gluconate proved that only zinc acetate was spermicidal. It appears this is due to the acetate in zinc acetate which may decrease oxygen utilization by sperm. Zinc acetate in vitro was antiviral while lyophilized aloe barbadensis was not. Lyophilized aloe barbadensis at concentrations of 7.5% and 10% proved to be spermicidal due to the multiple micro elements (boron, barium, calcium, chromium, copper, iron, potassium, magnesium, manganese, phosphorus, and zinc) which were toxic to the tail causing instant immobilization. The two compounds did not irritate or cause ulceration of rabbit vaginal epithelium. These results suggest the possibility of using zinc acetate and lyophilized aloe barbadensis as a new, effective and safe vaginal contraceptive.

Acetates↗
PubMed1975

Effect of full agonists following calcium deprivation in rat vas deferens.

The contractile effects of maximum doses of adrenaline, noradrenaline, methacholine, acetylcholine, serotonin and barium chloride were studied following substitution of a medium without calcium for the normal nutrient solution. Except for the last agonist, the effects fall to about 10% within the first 3 min with prompt return to normal value upon reintroduction of regular fluid. This recovery is, however, slower if the previous incubation in Ca-free solution is prolonged. When barium chloride is used in a calcium-free medium, the maximum height of contractions falls exponentially at a t1/2 of about 180 min. This decay can be accelerated by giving successive 5-min doses of the agonist or by using EDTA. It is hypothesised that excitation--contraction coupling in rat vas deferens depends on at least two different calcium sources: a deep site associated with the effects of barium, and a superficial one, related to the other agonists. To explain the slow recovery after prolonged calcium lack, a third compartment in series with the latter is suggested. No indication is found that the biphasic effects of barium depend on two different calcium pools.

Acetylcholine↗
PubMed2000

Sugar interaction with metal ions. FT-IR study on the structure of crystalline galactaric acid and its K+, NH4+, Ca2+, Ba2+, and La3+ complexes.

The FT-IR spectra of galactaric acid and its K+, NH4+, Ca2+, Ba2+, and La3+ salts have been recorded and interpreted. Spectroscopic evidence shows that the dimeric carboxylic groups of the free acid are dissociated upon formation of the salt, and the asymmetric and symmetric stretching vibrations of the anionic COO- group in these salts are observed at about 1600 and 1400 cm-1, respectively. The two carboxylic groups of the galactarate coordinate with Ca2+ ions in a monodentate form. One of the carboxylic groups in the Ba2+ salt coordinates in a monodentate state; another group interacts with three cations in a tetradentate form. In the K+, NH4+, and La3+ salts, the COO- groups coordinate in a polydentate manner with the cations. By comparison of the spectra of the salts with that of the free acid, it is concluded that the hydroxyl groups of the galactarate skeleton take part in metal-oxygen interaction, and the hydrogen-bonding network is rearranged upon sugar metalation. The degree of participation of the sugar OH groups in metal-galactarate interaction is varied from the K+ and NH4+ salts to the Ca2+, Ba2+, and La3+ salts.

Barium↗