Effects of internal sodium and hydrogen ions and of external calcium ions and membrane potential on calcium entry in squid axons.

Mullins, L. J.; Tiffert, Teresa; Vassort, Guy; Whittembury, J

doi:10.1113/jphysiol.1983.sp014674

Cited by 49 publications

(45 citation statements)

References 32 publications

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“…A possible explanation is considered here. Mullins et al (1983) & Lederer, 1985). For example, Eisner et al (1983b) concluded that both an increase of aia and a depolarization are required to increase tonic tension in sheep Purkinje fibres.…”

Section: Resultsmentioning

confidence: 99%

Effects of repetitive activity on developed force and intracellular sodium in isolated sheep and dog Purkinje fibres.

Boyett

Hart

Levi

et al. 1987

The Journal of Physiology

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SUMMARY1. When cardiac muscle is stimulated after a rest there is a gradual increase in force development over several minutes. The origin of this 'force staircase' was investigated in experiments on sheep and dog Purkinje fibres. Particular attention was paid to the possible role of changes in the intracellular Na+ activity (aNa).2. The first line of evidence for a role for aka came from a comparison of sheep and dog Purkinje fibres generating action potentials: after a change in the stimulus rate the slow changes of both a'a and force were monophasic in sheep but biphasic in dog preparations.3. In the remaining experiments changes in aia and force in sheep preparations were measured during 4 min trains of voltage-clamp pulses at a frequency of 2-5 Hz.4. A number of these voltage-clamp experiments also indicated that changes in aka are involved. Depending on the preparation and the duration of the pulses aka rose or fell during a train -a rise in a'a was always associated with a gradual rise in force, whereas a fall in aka was usually accompanied by a gradual fall in force.The addition of tetrodotoxin (TTX) or the use of a low holding potential reduced the progressive rises of both a'a and force, whereas the inclusion of a 10 mV hyperpolarization between pulses potentiated the progressive rises of both.5. The effect of TTX on the staircase was more marked the longer the pulses during the train; this possibly indicates that the effect of aNa on the force staircase is complex and is more marked with longer pulses. 6. A rise in aia was shown not to be the only factor underlying the progressive increase in force, because in many preparations a gradual rise in force occurred in spite of no change or even a fall of aNa.7. It is concluded that an increase in aka is involved in the slow increase in force during the staircase accompanying a train of action potentials, and that other factors are also involved; various possibilities are discussed.

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Section: Resultsmentioning

confidence: 99%

Effects of repetitive activity on developed force and intracellular sodium in isolated sheep and dog Purkinje fibres.

Boyett

Hart

Levi

et al. 1987

The Journal of Physiology

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“…An alternative hypothesis which is that the selectivity of the channel for cations (Cs+ and Tris+) against anions (C1-and aspartate) depends on both pH, and pHO, is unattractive because of the changes in pHi measured in depolarized Helix neurones (Thomas' & Meech, 1982). To account H+ CURRENTS IN SNAIL NEURONES intracellular sites (Meech & Thomas, 1977Ahmed & Connor 1980; Mullins, Tiffert, Vassort & Whittembury, 1983). As a consequence of this buffering, the increase in [Ca2+], produced by each action potential is believed to be restricted to a narrow shell of cytoplasm next to the surface membrane (Smith & Zucker, 1980).…”

Section: Discussionmentioning

confidence: 99%

Rapidly activating hydrogen ion currents in perfused neurones of the snail, Lymnaea stagnalis.

Byerly¹,

Meech²,

Moody³

1984

The Journal of Physiology

169

246

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SUMMARY1. Cells from the circumoesophageal nerve ring of the pond snail Lymnaea 8tagnali8 were internally perfused with solutions containing Cs aspartate, EGTA and pH buffers. Time-dependent, voltage-dependent 'residual' outward currents were observed at positive potentials. They were found to be carried largely by H+.2. The outward H+ currents were reduced by high internal pH, low external pH, external Cd2+ and 4-aminopyridine. External tetraethylammonium ions reduced the H+ currents but had a more effective blocking action on the K+ currents in these cells. All five agents reduced the maximum H+ conductance. In addition Cd2+, low external pH and high internal pH were found to shift the voltage dependence of the H+ current to more positive potentials.3. There was no significant difference between H+ currents recorded with the internal pCa2+ about 7 and those recorded with the internal pCa2+ near 5.4. It is likely that the H+ channel described here provides the basis for the increase in H+ permeability described by Thomas & Meech (1982) in depolarized Helix neurones.

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“…2). The overall vibrations in the infrared spectra of both samples are typical of NaP zeolite [24]; the fundamental features at 994, 740, 675, 605 and 432 cm −1 were assigned generally to different vibrations of adjacent tetrahedra and framework atoms in the zeolite lattice [16,24,25]. The bands at about 994 and 432 cm −1 are due to internal vibrations of (Si,Al)O 4 tetrahedra of NaP zeolite which are insensitive to framework structure.…”

Section: Ftir Spectramentioning

confidence: 99%

“…The bands at about 994 and 432 cm −1 are due to internal vibrations of (Si,Al)O 4 tetrahedra of NaP zeolite which are insensitive to framework structure. These bands result from stretching and bending modes of the T-O (T=Si or Al) units [16], respectively. The shifting of the T-O band generally located around 1090-1040 cm −1 for aluminosilicates containing five-membered rings to lower frequencies (994 cm −1 ), indicates zeolitization of the reacted slurry to NaP zeolite.…”

Section: Ftir Spectramentioning

confidence: 99%

“…The residual Ca(II) in sample solution was analyzed by UV-vis spectroscopy at 620 nm absorbance. The color intensity of a purple complex formed in situ from the reaction of Ca(II) and Arsenazo III is direct ly proportional to the adsorption capacity of the samples in the batch-reactor [16,17]. The amount of calcium adsorbed was calculated using the relation:…”

Section: Kinetic Experimentsmentioning

confidence: 99%

See 1 more Smart Citation

Controllable synthesis of NaP zeolite and its application in calcium adsorption

et al. 2015

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functional performance of the different kinds of zeolites, many studies have been devoted to improving synthetic approaches to control crystal size, the size of the intracrystalline pore/channel system and morphology of zeolites [5,6].Among various types of zeolites, NaP (Na 6 [(AlO 2 ) 6 (SiO 2 ) 10 ]⋅15H 2 O) is one of the most interesting structured zeolite with two sets of intersecting channels: 0.31 nm × 0.44 nm and 0.26 nm × 0.49 nm. According to International Zeolite Association (IZA), this structure is called "Gismondine" (GIS) framework topology [7,8]. NaP zeolite offers the greatest promise for gas separation applications due to its small pore size [9,10], and is also useful for removal of toxic and radioactive waste species like Cs, Sr, Ba, Pb, U, heavy metals, and ammonium from wastewater, seawater potassium extraction and formation of environmental friendly detergent [11,12]. NaP zeolite can be synthesized from various precursor materials and various methods. It can be synthesized from: (i) clay at a crystallization temperature of 85ºC [13], (ii) sodium silicate solution [14], and (iii) high silicon fly ash of coal combustion at 120ºC for 4 h [15]. Among them the most common methods used for the synthesis of NaP zeolite are the sol-gel technique, hydrothermal synthesis and microwave heating synthesis [1]. The NaP zeolite with different morphologies can offer many intriguing properties: places to store the guest molecules and to perform chemical reactions with selected-sized molecules. Thus, the NaP zeolite morphology and its important correlation with properties is the need of the recent research.In this work, we attempted the template free hydrothermal synthesis of NaP under controlled conditions. Based on multiple paths that can be involved in the hydrothermal synthesis of NaP, optimization of crystallization conditions was adapted through variation of the following parameters: Na 2 O/SiO 2 and SiO 2 /Al 2 O 3 molar ratios, aging time and aging temperature. The characteristics of the synthesized gels NaP zeolite particles were prepared through a template-free hydrothermal condition at 100ºC. Parameters like Na2O/SiO2 and SiO2/Al2O3 molar ratios, gel aging time and aging temperature were investigated for regulating the crystallization of the final product. The samples at different synthesis stages were characterized with N2 adsorption at −196ºC, field emission scanning electron microscopy (FE-SEM), temperature programmed desorption of ammonia adsorption, X-ray diffraction, thermogravimetric and differential scanning calorimetry analysis and Fourier transform infrared spectroscopy. The experimental results evidenced that a high ordering crystallinity of NaP zeolite was obtained at Na2O/SiO2 and SiO2/Al2O3 molar ratios of 1.10 and 1.40, respectively, and a temperature of 100°C for 4 days of aging. FE-SEM image exhibited polycrystalline aggregates of NaP zeolite with crystallite sizes ranging up to 5.04 μm with cactus/cabbage like structures. The quantitative analysis of the total number of acid sites...

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Effects of internal sodium and hydrogen ions and of external calcium ions and membrane potential on calcium entry in squid axons.

Cited by 49 publications

References 32 publications

Effects of repetitive activity on developed force and intracellular sodium in isolated sheep and dog Purkinje fibres.

Effects of repetitive activity on developed force and intracellular sodium in isolated sheep and dog Purkinje fibres.

Rapidly activating hydrogen ion currents in perfused neurones of the snail, Lymnaea stagnalis.

Controllable synthesis of NaP zeolite and its application in calcium adsorption

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