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1.
P. G. Kostyuk 《Neurophysiology》1997,29(4-5):191-194
Calcium ions are the most universal intracellular messengers transmitting signals from the plasmalemma of excitable cells
to the intracellular structures and triggering or modulating in this way most cellular functions. The molecular mechanisms
responsible for injection of Ca ions into the cytoplasm during cellular activity and for producting transient elevations of
their cytoplasmic free level (calcium “transient,” or “signals”) have been a subject of extensive investigation in numerous
laboratories during last three decades. In a short review it is impossible to summarize the results obtained; two extensive
publications on this subject have appeared already from our laboratory [1, 2]. Therefore, here the main attention will be
paid to the most recent data from our laboratory concerning different aspects of the mechanisms forming calcium signals in
neuronal cells. 相似文献
2.
The functional decline of selected proteins or organelles leads to aging at the intracellular level. Identification of these
proteins or organelles is usually challenging to traditional single-factor approaches since these factors are inter-connected
via feedback or feedforward controls. Establishing a feedback control model to simulate the interactions of multiple factors
is an insightful approach to guide the search for proteins involved in aging. However, there are only a few mathematical models
describing the age-dependent accumulation of DNA mutations, which are directly or indirectly induced by deterioration of the
intracellular environment including alteration of calcium homeostasis, a contributor of aging. Thus, based on Cui and Kaandorp’s
model, we develop an age-dependent mathematical model for the calcium homeostasis in budding yeast Saccharomyces cerevisiae. Our model contains cell cycle-dependent aging factors and can qualitatively reproduce calcium shocks and calcium accumulations
in cells observed in experiments. Using this model, we predict calcium oscillations in wild type, pmc1Δ, and pmr1Δ cells. This prediction suggests that Pmr1p plays a major role in regulating cytosolic calcium. Combining the model with
our experimental lifespan data, we predict an upper-limit of cytosolic calcium tolerance for cell survival. This prediction
indicates that, for aged cells (>35 generations), no pmr1 Δ can tolerate the cytosolic calcium concentration of 0.1 μM while a very small fraction (1%) of aged wild type cells (>50
generations) can tolerate a high cytosolic calcium concentration of 0.5 μM. 相似文献
3.
J. Emanuelsson 《Plant and Soil》1984,78(3):325-334
Summary The purpose of the present work has been to investigate the influence of calcium supply on root growth in barley. The plants
were grown in pots, in which the upper part was a sand-perlite mixture and the lower part a test solution with varying calcium
concentration (10−6–10−2 M CaCl2). The two parts were separated by a peat layer impeding a calcium transport from the upper to the lower part.
The growth of the roots in the test media was examined daily by counting the total number of roots and the number of roots
with laterals. The development of the number of roots had an exponential course at all calcium concentrations and was enhanced
by increased calcium concentration. At harvest it was found that the size of the roots (length and dry weight) decreased with
decreasing calcium concentration to a certain extent. 相似文献
4.
In neurons of the rat dorsal root ganglia (DRG), using a patch-clamp technique in the whole-cell configuration, we studied
the characteristics of calcium channels activated by depletion of the ryanodine-sensitive calcium stores of the endoplasmic
reticulum. Current-voltage (I-V) relationships of these store-operated calcium channels were obtained by subtraction of the
integral I-V characteristics after application of caffeine from the integral I-V characteristics of calcium channels in the
control. Currents through store-operated calcium channels could be induced by application of a series of hyperpolarization
current pulses to the cell under conditions of replacement of a calcium-free solution containing caffeine by a caffeine-free
solution containing 2 mM Ca2+. In this case, the following two main conditions were abserved: Voltage-operated calcium channels were inactivated, while
a gradient of the electrochemical potential for calcium ions was increased, which made easier passing of these currents through
store-operated calcium channels. Therefore, we found that in DRG neurons, despite the presence of great numbers of both voltage-operated
and receptor-dependent calcium channels, one more mechanism underlying the entry of calcium through store-operated channels
does exist.
Neirofiziologiya/Neurophysiology, Vol. 39, No. 3, pp. 195–200, May–June, 2007. 相似文献
5.
Calcium plays an essential role in excitation-contraction coupling in muscle, and derangements in calcium handling can produce
a variety of potentially harmful conditions, especially in cardiac muscle. In cardiac tissue specialized invaginations of
the sarcolemma, called T-tubules, penetrate deep into each sarcomere, and depolarization of the SL leads to an influx of calcium
through voltage-sensitive channels in the T-tubules that in turn triggers further calcium release from the sarcoplasmic reticulum
via ryanodine-sensitive calcium channels. Under certain conditions, such as elevated external Ca2+, cardiac cells can release calcium from the sarcoplasmic reticulum spontaneously, producing a calcium ’spark’ and propagating
traveling waves of elevated Ca2+ concentration, without depolarization of the SL (Wier and Blatter, 1991a, Cell Calcium
12, 241–254; Williams, 1993, Cell Calcium
14, 724–735; Cheng et al., 1993a, Science
262, 740–744). However, under normal resting conditions these potentially harmful waves seldom occur. In this paper we investigate
the role of the periodic distribution of ryanodine-sensitive channels in determining whether a spark can trigger a wave, using
a modification of the kinetic model proposed by Tang and Othmer, 1994b, Biophys. J.
67, 2223–2235, for calcium-induced calcium release. We show that the spatial localization of these channels near the T-tubules
has a significant effect on both wave propagation and the onset of oscillations in this system. Spatial localization provides
a possible explanation for the differing effects of various experimental protocols on the system’s ability to propagate a
traveling wave.
Supported in part by NIH Grant GM29123. 相似文献
6.
Using the whole-cell voltage-clamp technique, the effects of the neuropeptide Phe-Met-Arg-Phe-NH2 (FMRFa) on two types of dihydropyridine-sensitive, high-voltage-activated calcium currents were investigated in isolated
neuroendocrine caudo-dorsal cells (CDCs), which control egg-laying in the molluscLymnaea stagnalis. These currents are: (1) a transient current (Τinact = ∼10–25 ms) with an activation threshold of −40 mV and maximal amplitude at +10 mV and (2) a sustained current (Τinact = ∼ 100–300 ms) with a threshold of −10 mV and apeak at +30 mV.
FMRFa caused a partial block of the calcium current that was rapid, reversible and dose-dependent (ED50 = 4.3 nM). The FMRFa-sensitive and insensitive currents differed in voltage-dependence of activation and inactivation, steady-state
inactivation characteristics and time course of recovery from inactivation, all indicating that FMRFa selectively suppressed
the sustained calcium current.
Internal perfusion of CDCs with GTP-γ-S or GDP-Β-S depressed the FMRFa response, suggesting the involvement of G-proteins.
Experiments aimed at elucidation of the signal transduction pathway between the FMRFa receptor and the calcium channel revealed
no involvement of second messengers and protein kinases. The FMRFa-induced inhibition of the sustained calcium current probably
results from a direct interaction between a G-protein, activated by the FMRFa receptor, and the calcium channel.
The selective inhibition of this calcium current is likely to decrease the influx of calcium during the action potential,
which will reduce the release of autoexcitatory CDC-peptides and contribute to a suppression of excitability. 相似文献
7.
P. G. Kostyuk 《Neurophysiology》2007,39(4-5):248-250
The review analyzes current concepts on the role of calcium signals in the process of synaptic neuron-to-neuron and neuron-effector
transmission and on the respective intracellular mechanisms (participation of different types of ion channels, mitochondria,
and endoplasmic reticulum). The involvement of calcium both in the transmission per se, in particular in the process of exocytotic neurotransmitter release, and in long-lasting modulations of the efficacy of
synaptic transmission (potentiation or depression) is considered.
Neirofiziologiya/Neurophysiology, Vol. 39, Nos. 4/5, pp. 290–293, July–October, 2007. 相似文献
8.
SO3 belongs to the O-superfamily of conotoxins and is known to have analgesic effects in experimental animals. In order to
explore the mechanism of its potential pharmacological actions, the effect of SO3 on synchronized spontaneous calcium spikes
was examined in cultured hippocampal networks by calcium imaging. Spontaneous oscillations of intracellular concentrations
of calcium (Ca2+) in the form of waves and spikes are found in cultured hippocampal networks. Exposure to increasing concentrations of SO3
resulted in a progressive decrease in synchronized spontaneous calcium spikes. The higher concentrations (0.1 μmol/L and 1 μmol/L)
of SO3 showed the strongest inhibition. The rank order of inhibition was 1 μmol/L > 0.1 μmol/L > 10 μmol/L > 0.01 μmol/L.
This action of SO3 in reducing synchronized calcium spikes suggests a possible application for therapeutic treatment of epilepsy. 相似文献
9.
Cells use intracellular free calcium concentration changes for signaling. Signal encoding occurs through both spatial and temporal modulation of the free calcium concentration. The encoded message is detected by an ensemble of intracellular sensors forming the family of calcium-binding proteins (CaBPs) which must faithfully translate the message using a new syntax that is recognized by the cell. The cell is home to a significant although limited number of genes coding for proteins involved in the signal encoding and decoding processes. In a cell, only a subset of this ensemble of genes is expressed, leading to a genetic regulation of the calcium signal pathways. Calmodulin (CaM), the most ubiquitous expressed intracellular calcium-binding protein, plays a major role in calcium signal translation. Similar to a hub, it is central to a large and finely tuned network, receiving information, integrating it and dispatching the cognate response. In this review, we examine the different steps starting with an external stimulus up to a cellular response, with special emphasis on CaM and the mechanism by which it decodes calcium signals and translates it into exquisitely coordinated cellular events. By this means, we will revisit the calcium signaling semantics, hoping that we will ease communication between scientists dealing with calcium signals in different biological systems and different domains. 相似文献
10.
Xuping Liu Liang Zhao Yigang Wang Xu Zhang Wen-Song Tan 《Biotechnology and Bioprocess Engineering》2010,15(3):414-420
One of the major restrictions on the production of adenoviral vectors (AdV) is due to the decrease in virus concentration
concomitant with an increase in cell concentration at infection (CCI) which is known as “cell density effect”, this could
be because of the limited access to the nutrients or significant accumulation of toxic by-products. However, current strategies,
such as developing robust serum-free medium and performing nutrient feeding, will partially address this issue. Therefore,
the objective of this study was to further optimize serum-free culture medium by exploring the influence of calcium ion on
virus production. Our studies showed that an optimal concentration of calcium ion significantly enhances AdV production, especially
at a high CCI. During the virus infection process, a high concentration of calcium ion (≥ 1 mM) caused a reduction in virus
infection efficiency, possibly as a result of cell aggregation. However, by optimizing the timing of the addition of calcium
ion (i.e., 12 hours post-infection [hpi]), high virus infection efficiency could be maintained. The addition of 0.1 to 2 mM calcium
ion at 12 hpi increased virus proliferation dose-dependently. Therefore, the optimal selection of both the concentration and
the supplementation time of calcium ion during the process of AdV production could minimize the “cell density effect,” and
a 2.6- and 3.2-fold increase in virus concentration could be achieved at CCI3 and CCI4, respectively. 相似文献
11.
To study changes in the cytoplasmic Ca2+ concentration ([Ca2+]i) and the total amount of calcium in cells, we used, respectively, the fluorescent dye fura 2/AM and the metallochrome dye
arsenazo III. The total amount of calcium in acinar cells after their incubation in calcium-free ATP-containing extracellular
solution decreased. The action of ATP induced a dose-dependent increase in the [Ca2+]i; the EC50 was, on average, 130 ± ± 36 μM. Calcium transients induced by ATP demonstrated no desensitization. Against the background
of a blocker of ionotropic P2X receptors, pyridoxal phosphate-6-azophenyl-2′,4′-disulfonic acid, we observed a decrease in
the ATP-induced calcium transients by 72%. In addition, these transients were reduced by 65% in the calcium-free milieu, while
after thapsigargin-induced exhaustion of the endoplasmic reticulum store they disappeared. This is indicative of the involvement
of metabotropic P2Y receptors in the formation of the above calcium transients. Therefore, P2X and P2Y receptors participate
in ATP-induced calcium signalling in acinar cells of the submandibular salivary gland; activation of these channels results
in a rise in the [Ca2+]i. The P2X receptors to a higher extent contribute to the formation of calcium signals; the P2Y-determined increase in the
[Ca2+]i is smaller (equal to about 35%). Therefore, the functionally active ligand-operated ionotropic P2Y receptors and metabotropic
G protein-related P2Y receptors do exist in acinar cells of the submandibular salivary gland and play an important role in
the control of functioning of this gland.
Neirofiziologiya/Neurophysiology, Vol. 37, Nos. 5/6, pp. 395–402, September–December, 2005. 相似文献
12.
Summary In two experiments with carnations grown in rockwool the effects of different cation ratios in the nutrient solution were
studied. The results showed that carnations need a high calcium supply. The crop did not appear to be sensitive to different
potassium-magnesium ratios in the nutrient solution.
In the nutrient solution added mole ratios K∶Ca∶Mg=55∶35∶10 seemed to be optimal. Such ratios in addition led to ratios of
55∶30∶15 in the root environment.
Tissue analysis showed that in younger leaves of peduncles harvested a potassium content of 900 mmol per kg dry matter was
optimal. For calcium a content of 350 and for magnesium 100–150 mmol per kg was needed.
Analytical data of plant-sap analyses were closely correlated with data gained by digestion of dried material. For potassium
and magnesium the relationships were linear. However, for calcium a curvilinear relationship was found.
In the experiments indications were obtained that a sufficient calcium supply suppressed foot rot in carnations. 相似文献
13.
The role of mitochondria in cell signaling is becoming increasingly apparent, to an extent that the signaling role of mitochondria appears to have stolen the spotlight from their primary function as energy producers. In this chapter, we will review the ionic basis of calcium handling by mitochondria and discuss the mechanisms that these organelles use to regulate the activity of plasma membrane calcium channels and transporters. 相似文献
14.
Elevated temperatures induce coral bleaching. To investigate subcellular changes in heat-stressed corals, we examined heat-shock
proteins (hsps) and the concentration of calcium in coral cells at elevated temperatures. After heat treatment, three hsps
with approximate molecular weights of 70, 60 and 35 kDa were prominent. The 35 kDa heat-shock protein was further demonstrated
to be heme oxygenase by immunoblotting, suggesting the involvement of oxidative stress in coral cells during heat treatment.
Since the expression of hsps needs the activation of a calcium signal, the change of intracellular calcium concentration in
coral cells was examined by a FURA 2 fluorescence method under heat treatment. Intracellular calcium concentration increased
at high temperatures with or without the presence of ambient calcium. The extent of the calcium concentration increase was
constant for at least 6 hours. This result indicates the existence of an active calcium signal in coral cells at elevated
temperatures.
Accepted: 4 August 1996 相似文献
15.
Pollen tubes ofLilium longiflorum were treated for 10–30 min with 10−5
M CoCl2, which binds to calcium channels in the plasma membrane and blocks them. Cobalt analyses were performed with the Heidelberg
proton microprobe, using 3 MeV protons, a beam current of about 200 pA, and a spot size of 3×5 μm2. X-ray spectra revealed that coblat has much higher concentrations in the cell than in the surrounding dried medium. The
line scans, taken along the longitudinal cell axis in 1-μm steps, showed a cobalt gradient similar to the calcium gradient
of the same cell. Based on our findings, we can conclude that neither do the cobalt signals come from the cell wall nor is
the cobalt exclusively bound to the intracellular calcium-binding sites. There-fore, the present results suggest a polar distribution
in calcium channels in the plasma membrane of pollen tubes. 相似文献
16.
Gilmanov IR Samigullin DV Vyskocil F Nikolsky EE Bukharaeva EA 《Journal of computational neuroscience》2008,25(2):296-307
The local calcium concentration in the active zone of secretion determines the number and kinetics of neurotransmitter quanta
released after the arrival of a nerve action potential in chemical synapses. The small size of mammalian neuromuscular junctions
does not allow direct measurement of the correlation between calcium influx, the state of endogenous calcium buffers determining
the local concentration of calcium and the time course of quanta exocytosis. In this work, we used computer modeling of quanta
release kinetics with various levels of calcium influx and in the presence of endogenous calcium buffers with varying mobilities.
The results of this modeling revealed the desynchronization of quanta release under low calcium influx in the presence of
an endogenous fixed calcium buffer, with a diffusion coefficient much smaller than that of free Ca2+, and synchronization occurred upon adding a mobile buffer. This corresponds to changes in secretion time course parameters
found experimentally (Samigullin et al., Physiol Res 54:129–132, 2005; Bukharaeva et al., J Neurochem 100:939–949, 2007). 相似文献
17.
Homann PH 《Photosynthesis research》2002,73(1-3):169-175
This minireview focuses on the early evidence for roles of chloride and calcium ions in reactions of photosynthetic electron
transport and on the reluctance with which an essential function of these inorganic ions in the process of water oxidation
was accepted. For example, Daniel Arnon's group initially refuted the conclusion of Otto Warburg, the discoverer of a ‘chloride
effect,’ that chloride was a ‘coenzyme.’ Their reasoning was that chloride had not been shown to be an essential mineral nutrient
of plants. In the case of calcium, the problem was that the first ‘calcium effects’ had been seen with preparations from cyanobacteria
rather than from green plants. While today the status of calcium and chloride as essential participants in the process of
water oxidation is rarely disputed, the nature of their involvement still eludes all experimental inquiries. Substantial progress
in this respect may come from recent refinements of the application of Fourier-transform infrared spectroscopy to the study
of photosynthetic water oxidation.
I dedicate this minireview to the memory of George Cheniae (1928–2001), my college for almost 40 years, whose excellance as
a scientist and fairness have been an inspiration, whose critical mind I admired, whose wit I enjoyed, and whose friendship
I cherished.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
18.
Elongation growth of plant cells occurs by stretching of cell walls under turgor pressure when intermolecular bonds in the
walls are temporarily loosened. The acid-growth theory predicts that wall loosening is the result of wall acidification because
treatments (including IAA and fusicoccin) that cause lowered wall pH cause elongation. However, conclusive evidence that IAA
primarily reduces wall pH has been lacking. Calcium has been reported to stiffen the cell walls. We have used a microelectrode
ion-flux measuring technique to observe directly, and non-invasively, the net fluxes of protons and calcium from split coleoptiles
of oats (Avena sativa L.) in unbuffered solution. Normal net fluxes are 10 nmol · m−2 · s−1 proton efflux and zero calcium flux. The toxin fusicoccin (1 μM) causes immediate efflux from tissue not only of protons,
but also of calcium, about 110 nmol · m−2 · s−1 in each case. The data fit the “weak acid Donnan Manning” model for ion exchange in the cell wall. Thus we associate the
known “acid-growth” effect of fusicoccin with the displacement of calcium from the wall by exchange for protons extruded from
the cytoplasm. Application of 10 μM IAA causes proton efflux to increase transiently by about 15 nmol · m−2 · s−1 with a lag of about 10 min. The calcium influx decreases immediately to an efflux of about 20 nmol · m−2 · s−1. It appears that auxin too causes an “acid-growth” effect, with extruded protons exchanging for calcium in the cell walls.
I. Arif is currently recieving an AIDAB scholarship. This work was supported by an Australian Research Council grant to I.A.
Newman. 相似文献
19.
We studied the peculiarities of permeability with respect to the main extracellular cations, Na+ and Ca2+, of cloned low-threshold calcium channels (LTCCs) of three subtypes, Cav3.1 (α1G), Cav3.2 (α 1H), and Cav3.3 (α1I), functionally expressed in Xenopus oocytes. In a calcium-free solution containing 100 mM Na+ and 5 mM calcium-chelating EGTA buffer (to eliminate residual concentrations of Ca2+) we observed considerable integral currents possessing the kinetics of inactivation typical of LTCCs and characterized by
reversion potentials of −10 ± 1, −12 ± 1, and −18 ± 2 mV, respectively, for Cav3.1, Cav3.2, and Cav3.3 channels. The presence of Ca2+ in the extracellular solution exerted an ambiguous effect on the examined currents. On the one hand, Ca2+ effectively blocked the current of monovalent cations through cloned LTCCs (K
d = 2, 10, and 18 μM for currents through channels Cav3.1, Cav3.2, and Cav3.3, respectively). On the other hand, at the concentration of 1 to 100 mM, Ca2+ itself functioned as a carrier of the inward current. Despite the fact that the calcium current reached the level of saturation
in the presence of 5 mM Ca2+ in the external solution, extracellular Na+ influenced the permeability of these channels even in the presence of 10 mM Ca2+. The Cav3.3 channels were more permeable with respect to Na+ (P
Ca/P
Na ∼ 21) than Cav3.1 and Cav3.2 (P
Ca/P
Na ∼ 66). As a whole, our data indicate that cloned LTCCs form multi-ion Ca2+-selective pores, as these ions possess a high affinity for certain binding sites. Monovalent cations present together with
Ca2+ in the external solution modulate the calcium permeability of these channels. Among the above-mentioned subtypes, Cav3.3 channels show the minimum selectivity with respect to Ca2+ and are most permeable for monovalent cations.
Neirofiziologiya/Neurophysiology, Vol. 38, No. 3, pp. 183–192, May–June, 2006. 相似文献
20.
A. V. Kononov N. V. Ball V. P. Zinchenko 《Biochemistry (Moscow) Supplemental Series A: Membrane and Cell Biology》2011,5(2):153-161
The subject of this work was to study the reasons of the variability of the calcium response amplitudes in individual neurons
of the hippocampal cell culture to agonists of ionotropic glutamate receptors and the regularities of the calcium response
amplitude distribution. Changes of [Ca2+]
i
in the neurons in response to the NMDA-, AMPA-, and KA-receptor agonists were recorded using fluorescence probe Fura-2. The
calcium response amplitudes (expressed as the ratio of fluorescence intensities of Fura-2 upon excitation at wave-lengths
340 and 380 nm) to short-term application of glutamate receptor agonists N-methyl-D-aspartate (NMDA), domoic acid (DA), α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA), and (S)-(−)-5-fluorowillardiine
(FW) were measured. Calcium responses of individual cells differed in shape and amplitude but always reproduced upon the second
application of the agonist. To elucidate the nature of calcium response variability, we compared distributions of calcium
response amplitudes to the NMDA-, KA-, and AMPA-receptor agonists in cultures of various ages in the presence of receptor
desensitization inhibitors and different agonist concentrations. An even increase from 0.05 to 1.6 was characteristic for
distributions of calcium response amplitudes. Nevertheless, in 1–3% neurons of the cell culture, calcium response amplitudes
reached much higher values. The efficiency of the ligands usually increased in the following order: FW ≈ NMDA > DA. However,
this regularity varied with age and depended on the presence of the receptor desensitization inhibitor. In the process of
growth and differentiation of neurons in culture from 1 to 14 day in vitro, calcium response amplitude to AMPA- and KA-receptor
agonists increased. Desensitization inhibitors transformed the response from pulse-like with a sharp peak into stepwise and
increased the amplitude of calcium responses but did not abolish the character of even amplitude distribution. The effect
of AMPA- and KA-receptor desensitization inhibitor decreased with calcium response amplitude growth in the control and approached
zero in neurons with initially maximal amplitude. KA- and AMPA-receptor agonists at high concentrations possessed a property
of desensitization inhibitors and transformed a transient response into a continuous one that lasted throughout the application
time. Thus, the amplitude and shape of the calcium response to glutamate receptor agonists is a characteristic parameter of
an individual cell. 相似文献