共查询到20条相似文献,搜索用时 31 毫秒
1.
Patricia A. Lampe Ellen B. Cornbrooks Anna Juhasz Eugene M. Johnson James L. Franklin 《Developmental neurobiology》1995,26(2):205-212
Rat sympathetic neurons undergo programmed cell death (PCD) in vitro and in vivo when they are deprived of nerve growth factor (NGF). Chronic depolarization of these neurons in cell culture with elevated concentrations of extracellular potassium ([K+]o) prevents this death. The effect of prolonged depolarization on neuronal survival is thought to be mediated by a rise of intracellular calcium concentration ([Ca2+]i) caused by Ca2+ influx through voltage-gated channels. In this report we investigate the effects of chronic treatment of rat sympathetic neurons with thapsigargin, an inhibitor of intracellular Ca2+ sequestration. In medium containing a normal concentration of extracellular Ca2+ ([Ca2+]o), thapsigargin caused a sustained rise of intracellular Ca2+ concentration and partially blocked death of NGF-deprived cells. Elevating [Ca2+]o in the presence of thapsigargin further increased [Ca2+]i, suggesting that the sustained rise of [Ca2+]i was caused by a thapsigargin-induced Ca2+ influx. This treatment potentiated the effect of thapsigargin on survival. The dihydropyridine Ca2+ channel antagonist, nifedipine, blocked both a sustained elevation of [Ca2+]i and enhanced survival caused by depolarization with elevated [K+]o, suggesting that these effects are mediated by Ca2+ influx through L-type channels. Nifedipine did not block the sustained rise of [Ca2+]i or enhanced survival caused by thapsigargin treatment, indicating that these effects were not mediated by influx of Ca2+ through L-type channels. These results provide additional evidence that increased [Ca2+]i can suppress neuronal PCD and identify a novel method for chronically raising neuronal [Ca2+]i for investigation of this and other Ca2+-dependent phenomena. © 1995 John Wiley & Sons, Inc. 相似文献
2.
The rise in intracellular Ca2+ mediated by AMPA subtype of glutamate receptors has been implicated in the pathogenesis of motor neuron disease, but the exact route of Ca2+ entry into motor neurons is not clearly known. In the present study, we examined the role of voltage gated calcium channels (VGCCs) in AMPA induced Ca2+ influx and subsequent intracellular signaling events responsible for motor neuron degeneration. AMPA stimulation caused sodium influx in spinal neurons that would depolarize the plasma membrane. The AMPA induced [Ca2+]i rise in motor neurons as well as other spinal neurons was drastically reduced when extracellular sodium was replaced with NMDG, suggesting the involvement of voltage gated calcium channels. AMPA mediated rise in [Ca2+]i was significantly inhibited by L-type VGCC blocker nifedipine, whereas ω-agatoxin-IVA and ω-conotoxin-GVIA, specific blockers of P/Q type and N-type VGCC were not effective. 1-Napthyl-acetyl spermine (NAS), an antagonist of Ca2+ permeable AMPA receptors partially inhibited the AMPA induced [Ca2+]i rise but selectively in motor neurons. Measurement of AMPA induced currents in whole cell voltage clamp mode suggests that a moderate amount of Ca2+ influx occurs through Ca2+ permeable AMPA receptors in a subpopulation of motor neurons. The AMPA induced mitochondrial calcium loading [Ca2+]m, mitochondrial depolarization and neurotoxicity were also significantly reduced in presence of nifedipine. Activation of VGCCs by depolarizing concentration of KCl (30 mM) in extracellular medium increased the [Ca2+]i but no change was observed in mitochondrial Ca2+ and membrane potential. Our results demonstrate that a subpopulation of motor neurons express Ca2+ permeable AMPA receptors, however the larger part of Ca2+ influx occurs through L-type VGCCs subsequent to AMPA receptor activation and consequent mitochondrial dysfunction is the trigger for motor neuron degeneration. Nifedipine is an effective protective agent against AMPA induced mitochondrial stress and degeneration of motor neurons. 相似文献
3.
《生物化学与生物物理学报:生物膜》1985,819(2):267-270
Activation of Na+-H+ exchange in rat thymocytes was found to be followed by an increase in free cytoplasmic Ca2+ concentration ([Ca2+]i). We determined whether the change in [Ca2+]i was secondary to the uptake of Na+, or to the cytoplasmic alkalinization that result from activation of the antiport. Increasing intracellular [Na+] by treating the cells with ouabain or gramicidin failed to affect [Ca2+]i. In contrast, procedures that increased the cytoplasmic pH, such as addition of monensin or NH3, significantly elevated [Ca2+]i. These results suggest an important role of cytoplasmic pH in the control of [Ca2+]i in lymphocytes. 相似文献
4.
Marc Gleichmann Leon P. Collis† Peter J. S. Smith† Mark P. Mattson 《Journal of neurochemistry》2009,109(2):644-655
In order to determine the sequence of cellular processes in glutamate toxicity, we simultaneously recorded O2 consumption, cytosolic Ca2+ concentration ([Ca2+]i), and mitochondrial membrane potential (mΔψ) in single cortical neurons. Oxygen consumption was measured using an amperometric self‐referencing platinum electrode adjacent to neurons in which [Ca2+]i and mΔψ were monitored with Fluo‐4 and TMRE+, respectively, using a spinning disk laser confocal microscope. Excitotoxic doses of glutamate caused an elevation of [Ca2+]i followed seconds afterwards by an increase in O2 consumption which reached a maximum level within 1–5 min. A modest increase in mΔψ occurred during this time period, and then, shortly before maximal O2 consumption was reached, the mΔψ, as indicated by TMRE+ fluorescence, dissipated. Maximal O2 consumption lasted up to 5 min and then declined together with mΔψ and ATP levels, while [Ca2+]i further increased. mΔψ and [Ca2+]i returned to baseline levels when neurons were treated with an NMDA receptor antagonist shortly after the [Ca2+]i increased. Our unprecedented spatial and time resolution revealed that this sequence of events is identical in all neurons, albeit with considerable variability in magnitude and kinetics of changes in O2 consumption, [Ca2+]i, and mΔψ. The data obtained using this new method are consistent with a model where Ca2+ influx causes ATP depletion, despite maximal mitochondrial respiration, minutes after glutamate receptor activation. 相似文献
5.
V. P. Zinchenko M. V. Turovskaya I. Yu. Teplov A. V. Berezhnov E. A. Turovsky 《Biophysics》2016,61(1):85-93
Subtypes of inhibitory GABAergic neurons containing Ca2+-binding proteins play a pivotal role in the regulation of spontaneous synchronous [Ca2+]i transients in a neuronal network. In this study it is shown that: (1) the interneurons that containing Ca2+-binding proteins at buffer concentration can be identified by the shape of Ca2+-signa1 in response to depolarization or activation of ionotropic glutamate receptors; (2) Ca2+-binding proteins are involved in desynchronization of spontaneous Ca2+ transients. At low frequencies of spontaneous synchronous [Ca2+]i transients (less than 0.2 Hz) neurons show quasi-synchronous pulsations. At higher frequencies, synchronization of spontaneous synchronous [Ca2+]i transients occurs in all neurons; (3) it is established that several synchronous oscillations with different frequencies coexist in the network and the amplitude of their depolarizing pulse also varies. This phenomenon is apparently the mechanism that selectively directs information in separate neurons using the same network; and (4) in one population of interneurons at high frequencies of spontaneous synchronous [Ca2+]i transients the inversion of Cl– concentration gradient is observed. In this case, the inhibition of GABA(A) receptors suppresses the activity of neurons in this population and excites other neurons in the network. Thus, the GABAergic neurons that contain Ca-binding proteins show different mechanisms to regulate the synchronous neuronal activities in cultured rat hippocampal cells. 相似文献
6.
A. M. Surin L. R. Gorbacheva I. G. Savinkova R. R. Sharipov B. I. Khodorov V. G. Pinelis 《Biochemistry. Biokhimii?a》2014,79(2):146-157
For the first time, simultaneous monitoring of changes in the concentration of cytosolic ATP ([ATP]c), pH (pHc), and intracellular free Ca2+ concentration ([Ca2+]i) of the individual neurons challenged with toxic glutamate (Glu) concentrations was performed. To this end, the ATP-sensor AT1.03, which binds to ATP and therefore enhances the efficiency of resonance energy transfer between blue fluorescent protein (energy donor) and yellow-green fluorescent protein (energy acceptor), was expressed in cultured hippocampal neurons isolated from 1–2-day-old rat pups. Excitation of fluorescence in the acceptor protein allowed monitoring changes in pHc. Cells were loaded with fluorescent low-affinity Ca2+ indicators Fura-FF or X-rhod-FF to register [Ca2+]i. It was shown that Glu (20 μM, glycine 10 μM, Mg2+-free) produced a rapid acidification of the cytosol and decrease in [ATP]c. An approximately linear relationship (r 2 = 0.56) between the rate of [ATP]c decline and latency of glutamate-induced delayed calcium deregulation (DCD) was observed: higher rate of [ATP]c decrease corresponded to shorter DCD latency period. DCD began with a decrease in [ATP]c of as much as 15.9%. In the phase of high [Ca2+]i, the plateau of [ATP]c dropped to 10.4% compared to [ATP]c in resting neurons (100%). In the presence of the Na+/K+-ATPase inhibitor ouabain (0.5 mM), glutamate-induced reduction in [ATP]c in the phase of the high [Ca2+]i plateau was only 36.6%. Changes in [ATP]c, [Ca2+]i, mitochondrial potential, and pHc in calcium-free or sodium-free buffers, as well as in the presence of the inhibitor of Na+/K+-ATPase ouabain, led us to suggest that in addition to increase in proton conductivity and decline in [ATP]c, one of the triggering factors of DCD might be a reversion of the neuronal plasma membrane Na+/Ca2+ exchange. 相似文献
7.
Kohno D Sone H Minokoshi Y Yada T 《Biochemical and biophysical research communications》2008,366(2):388-392
Ghrelin, an orexigenic hormone, directly activates neuropeptide (NPY) neurons in the hypothalamic arcuate nucleus (ARC), and thereby stimulates food intake. The hypothalamic level of AMP-activated protein kinase (AMPK), an intracellular energy sensor, is activated by peripheral and central administration of ghrelin. We examined whether ghrelin regulates AMPK activity in NPY neurons of the ARC. Single neurons were isolated from the ARC and cytosolic Ca2+ concentration ([Ca2+]i) was measured by fura-2 microfluorometry, followed by immunocytochemical identification of NPY, phospho-AMPK, and phospho-acetyl-CoA carboxylase (ACC). Ghrelin and AICAR, an AMPK activator, increased [Ca2+]i in neurons isolated from the ARC. The ghrelin-responsive neurons highly overlapped with AICAR-responsive neurons. The neurons that responded to both ghrelin and AICAR were primarily NPY-immunoreactive neurons. Treatment with ghrelin increased phosphorylation of AMPK and ACC. An AMPK inhibitor, compound C, suppressed ghrelin-induced [Ca2+]i increases. These results demonstrate that ghrelin increases [Ca2+]i via AMPK-mediated signaling in the ARC NPY neurons. 相似文献
8.
《Cell calcium》2020
Intracellular [Na+]i and [Ca2+]i imbalance significantly contribute to neuro-axonal dysfunctions and maladaptive myelin repair or remyelination failure in chronic inflammatory demyelinating diseases such as multiple sclerosis. Progress in recent years has led to significant advances in understanding how [Ca2+]i signaling network drive degeneration or remyelination of demyelinated axons.The Na+/Ca2+ exchangers (NCXs), a transmembrane protein family including three members encoded by ncx1, ncx2, and ncx3 genes, are emerging important regulators of [Na+]i and [Ca2+]i both in neurons and glial cells. Here we review recent advance highlighting the role of NCX exchangers in axons and myelin-forming cells, i.e. oligodendrocytes, which represent the major targets of the aberrant inflammatory attack in multiple sclerosis. The contribution of NCX subtypes to axonal pathology and myelin synthesis will be discussed. Although a definitive understanding of mechanisms regulating axonal pathology and remyelination failure in chronic demyelinating diseases is still lacking and requires further investigation, current knowledge suggest that NCX activity plays a crucial role in these processes. Defining the relative contributions of each NCX transporter in axon pathology and myelinating glia will constitute not only a major advance in understanding in detail the intricate mechanism of neurodegeneration and remyelination failure in demyelinating diseases but also will help to identify neuroprotective or remyelinating strategies targeting selective NCX exchangers as a means of treating MS. 相似文献
9.
《Cell calcium》2019
Rat melanotrophs express several types of voltage-gated and ligand-gated calcium channels, although mechanisms involved in the maintenance of the resting intracellular Ca2+ concentration ([Ca2+]i) remain unknown. We analyzed mechanisms regulating resting [Ca2+]i in dissociated rat melanotrophs by Ca2+-imaging and patch-clamp techniques. Treatment with antagonists of L-type, but not N- or P/Q-type voltage-gated Ca2+ channels (VGCCs) as well as removal of extracellular Ca2+ resulted in a rapid and reversible decrease in [Ca2+]i, indicating constitutive Ca2+ influx through L-type VGCCs. Reduction of extracellular Na+ concentration (replacement with NMDG+) similarly decreased resting [Ca2+]i. When cells were champed at –80 mV, decrease in the extracellular Na+ resulted in a positive shift of the holding current. In cell-attached voltage-clamp and whole-cell current-clamp configurations, the reduction of extracellular Na+ caused hyperpolarisation. The holding current shifted in negative direction when extracellular K+ concentration was increased from 5 mM to 50 mM in the presence of K+ channel blockers, Ba2+ and TEA, indicating cation nature of persistent conductance. RT-PCR analyses of pars intermedia tissues detected mRNAs of TRPV1, TRPV4, TRPC6, and TRPM3-5. The TRPV channel blocker, ruthenium red, shifted the holding current in positive direction, and significantly decreased the resting [Ca2+]i. These results indicate operation of a constitutive cation conductance sensitive to ruthenium red, which regulates resting membrane potential and [Ca2+]i in rat melanotrophs. 相似文献
10.
《Journal of receptor and signal transduction research》2013,33(6):550-558
AbstractObjective: Spinorphin is a potential endogenous antinociceptive agent although the mechanism(s) of its analgesic effect remain unknown. We conducted this study to investigate, by considering intracellular calcium concentrations as a key signal for nociceptive transmission, the effects of spinorphin on cytoplasmic Ca2+ ([Ca2+]i) transients, evoked by high-K+ (30?mM) depolariasation or capsaicin, and to determine whether there were any differences in the effects of spinorphin among subpopulation of cultured rat dorsal root ganglion (DRG) neurons. Methods: DRG neurons were cultured on glass coverslips following enzymatic digestion and mechanical agitation, and loaded with the calcium sensitive dye fura-2 AM (1?µM). Intracellular calcium responses in individual DRG neurons were quantified using standard fura-2 based ratiometric calcium imaging technique. All data were analyzed by using unpaired t test, p?<?0.05 defining statistical significance. Results: Here we found that spinorphin inhibited cytoplasmic Ca2+ ([Ca2+]i) transients, evoked by depolarization and capsaicin selectively in medium and small cultured rat DRG neurons. Spinorphin (10–300?µM) inhibited the Ca2+ signals in concentration dependant manner in small- and medium diameter DRG neurons. Capsaicin produced [Ca2+]i responses only in small- and medium-sized DRG neurons, and pre-treatment with spinorphin significantly attenuated these [Ca2+]i responses. Conclusion: Results from this study indicates that spinorphin significantly inhibits [Ca2+]i signaling, which are key for the modulation of cell membrane excitability and neurotransmitter release, preferably in nociceptive subtypes of this primary sensory neurons suggesting that peripheral site is involved in the pain modulating effect of this endogenous agent. 相似文献
11.
Trans-2-Pentenal (pentenal), an α,β-unsaturated aldehyde, induces increases in [Ca2+]i in cultured neonatal rat trigeminal ganglion (TG) neurons. Since all pentenal-sensitive neurons responded to a specific TRPA1 agonist, allyl isothiocyanate (AITC) and neurons from TRPA1 knockouts failed to respond to pentenal, TRPA1 appears to be sole initial transduction site for pentenal-evoked trigeminal response, as reported for the structurally related irritant, acrolein. Furthermore, because the neuronal sensitivity to pentenal is strictly dependent upon the presence of extracellular Na+/Ca2+, as we showed previously, we investigated which types of voltage-gated sodium/calcium channels (VGSCs/VGCCs) are involved in pentenal-induced [Ca2+]i increases as a downstream mechanisms. The application of tetrodotoxin (TTX) significantly suppressed the pentenal-induced increase in [Ca2+]i in a portion of TG neurons, suggesting that TTX-sensitive (TTXs) VGSCs contribute to the pentenal response in those neurons. Diltiazem and ω-agatoxin IVA, antagonists of L- and P/Q-type VGCCs, respectively, both caused significant reductions of the pentenal-induced responses. ω-Conotoxin GVIA, on the other hand, caused only a small decrease in the size of pentenal-induced [Ca2+]i rise. These indicate that both L- and P/Q-type VGCCs are involved in the increase in [Ca2+]i produced by pentenal, while N-type calcium channels play only a minor role. This study demonstrates that TTXs VGSCs, L- and P/Q-type VGCCs play a significant role in the pentenal-induced trigeminal neuronal responses as downstream mechanisms following TRPA1 activation. 相似文献
12.
The effect of hyposmotic and isosmotic cell swelling on the free intracellular calcium concentration ([Ca2+]i) in rat mammary acinar cells has been examined using the fura-2 dye technique. A hyposmotic shock (40% reduction) increased the [Ca2+]i in rat mammary acinar cells in a fashion which was transient; the [Ca2+]i returned to a value similar to that found under isomotic conditions within 180 sec. The increase in the [Ca2+]i was dependent upon the extent of the osmotic shock. The hyposmotically-activated increase in the [Ca2+]i could not be attributed to a reduction in extracellular Na+ or a change in the ionic strength of the incubation medium. Thapsigargin (1 M) enhanced the hyposmotically-activated increase in the [Ca2+]i. Isosmotic swelling of rat mammary acinar cells, using urea, had no significant effect on the [Ca2+]i. Similarly, a hyperosmotic shock did not affect the [Ca2+]i in rat mammary acinar cells. It appears that the effect of cell swelling on the [Ca2+]i in rat mammary acinar cells depends on how the cells are swollen (hyposmotic vs. isosmotic). This finding may have important physiological implications given that it is predicted that mammary cell volume will change in vivo under isomotic conditions. 相似文献
13.
Intracellular calcium ([Ca2+]i) plays a pivotal role in neuronal ischemia. The aim of the present study was to investigate the routes of Ca2+ entry during non-excitotoxic oxygen and glucose deprivation (OGD) in acutely dissociated rat CA1 neurons. During OGD the fluo-3/fura red ratio reflecting [Ca2+]i increased rapidly and irreversibly. [Ca2+]i increased to the same degree in Ca2+ depleted medium, and also when both the ryanodine receptors (RyR) and the inositol 1,4,5-trisphosphate (IP3) receptors were blocked. When the endoplasmic reticulum (ER) Ca2+ stores were emptied with thapsigargin no increase in [Ca2+]i was observed independent of extracellular Ca2+. The OGD induced Ca2+ deregulation in isolated CA1 neurons is not prevented by removing Ca2+, or by blocking the IP3– or RyR receptors. However, when SERCA was blocked, no increase in [Ca2+]i was observed suggesting that SERCA dysfunction represents an important mechanism for ischemic Ca2+ overload. 相似文献
14.
15.
Roberto Sánchez-Olea Herminia Pasantes-Morales Prof. Arne Schousboe 《Neurochemical research》1993,18(2):147-152
The effect of hyposmotic conditions on the concentration of intracellular free calcium ([Ca2+]i) was studied in cultured cerebellar granule cells and cerebral cortical neurons after loading of the cells with the fluorescent Ca2+ chelator Fluo-3. It was found that in both types of neurons exposure to media with a decrease in osmolarity of 20 to 50% of the osmolarity in the isosmotic medium (320 mOsm) led to a dose dependent increase in [Ca2+]i with a time course showing the highest value at the earliest measured time point, i.e. 40 s after exposure to the hyposmotic media and a subsequent decline towards the basal level during the following 320 s. The response in the cortical neurons was larger than in the granule cells but both types of neurons exhibited a similar increase in [Ca2+]i after expoxure to 50 mM K+ which was of the same magnitude as the increase in [Ca2+]i observed in the cortical neurons exposed for 40 s to a medium with a 50% reduction in osmolarity. In both types of neurons the blocker of voltage gated Ca2+ channels verapamil had no effect on the hyposmolarity induced increase in [Ca2+]i. On the contrary, this increase in [Ca2+]i was dependent upon external calcium and could be inhibited partly or completely by the inorganic blockers of Ca2+ channels Mg2+ and La3+. Dantrolene which prevents release of Ca2+ from internal stores had no effect. The results show that exposure of neurons to hyposmotic conditions leading to swelling results in a large increase in free intracellular Ca2+ which represents an influx of Ca2+ rather than a release of Ca2+ from internal, dantrolene sensitive stores. 相似文献
16.
Ahmet Ayar Mete Ozcan Ergul Alcin Ihsan Serhatlioglu Sibel Ozcan Selim Kutlu Haluk Kelestimur 《Journal of physiology and biochemistry》2014,70(1):43-48
In addition to its well-known effects on parturition and lactation, oxytocin (OT) plays an important role in modulation of pain and nociceptive transmission. But, the mechanism of this effect is unclear. To address the possible role of OT on pain modulation at the peripheral level, the effects of OT on intracellular calcium levels ([Ca2+]i) in rat dorsal root ganglion (DRG) neurons were investigated by using an in vitro calcium imaging system. DRG neurons were grown in primary culture following enzymatic and mechanical dissociation of ganglia from 1- or 2-day-old neonatal Wistar rats. Using the fura-2-based calcium imaging technique, the effects of OT on [Ca2+]i and role of the protein kinase C (PKC)-mediated pathway in OT effect were assessed. OT caused a significant increase in basal levels of [Ca2+]i after application at the doses of 30 nM (n?=?34, p?<?0.01), 100 nM (n?=?41, p?<?0.001) and 300 nM (n?=?46, p?<?0.001). The stimulatory effect of OT (300 nM) on [Ca2+]i was persistent in Ca2+-free conditions (n?=?56, p?<?0.01). Chelerythrine chloride, a PKC inhibitor, significantly reduced the OT-induced increase in [Ca2+]i (n?=?28, p?<?0.001). We demonstrated that OT activates intracellular calcium signaling in cultured rat primary sensory neurons in a dose- and PKC-dependent mechanism. The finding of the role of OT in peripheral pain modification may serve as a novel target for the development of new pharmacological strategies for the management of pain. 相似文献
17.
Peptidesecreting neurons from crustacean X-organ regenerating in defined culture possess different ionic current profiles correlated with two distinct morphological types, veiling and branching; voltage-dependent Ca2+ current is prominent in neurons consistently extending large veils, but is small in neurons that repetitively branch. Intracellular free calcium ([Ca2+]i) have been implicated in regulation of neurite outgrowth underlying the establishment of distinct morphologies. Here, basal [Ca2+]i was measured by fura-2 fluorescence ratio imaging from these morphologically distinct neurons and compared. Both morphological tapes can extend out processes over a [Ca2+]i range (approximately 50 to 300 nM) that is much greater than that reported for neurons of other phyla. Application of high k+ saline led to increases in [Ca2+]i in soma, neurite, and lamellipodium of veiling neurons. Increase were great for veiling than branching neurons. These observations were consistent with the previous voltage clamp data for calcium currents. Media altered to perturb [Ca2+]i were used to assess the role of [Ca2+]i in veiling or branching outgrowth programs. Outgrowth of veiling cells was arrested addition of 100 μMCD2+, a calcium channel blocker. Outgrowth resumed following brief exposures to Cd2+. Branching neurons were unaffected by Cd2+. Cd2+ at lower levels (10 μM) had no effect on outgrowth of either neuronal type, whereas at higher levels (1 mM), outgrowth of both types was arrested. Reduction of extracellular sodium to 0.001 of normal concentration stopped veiling outgrowth, but branching outgrowth continued, although it was less robust. Addition of tetrodotoxin (1 μM) did not alter outgrowth of either neuronal type relative to controls. Thus, peptidergic neurons of differing intrinsic morphologies maintain similar basal [Ca2+]i levels under identical culture conditions, yet show differing sensitivities to manipulations influencing [Ca2+]i with respect to regenerative outgrowth, but not its form. 1994 John Wiley & Sons, Inc. 相似文献
18.
T. P. Storozhevykh Ya. E. Senilova T. Brustovetsky V. G. Pinelis N. Brustovetsky 《Neurochemical research》2010,35(2):323-335
KB-R7943, an inhibitor of a reversed Na+/Ca2+ exchanger, exhibits neuroprotection against glutamate excitotoxicity. Taking into consideration that prolonged exposure of
neurons to glutamate induces delayed calcium deregulation (DCD) and irreversible decrease of mitochondrial membrane potential
(Δψmit), we examined the effect of KB-R7943 on glutamate and kainate-induced [Ca2+]i and on Δψmit changes in rat cultured cerebellar granule neurons. 15 μmol/l KB-R7943 significantly delayed the onset of DCD in response
to kainate but not in response to glutamate. In spite of [Ca2+]i overload, KB-R7943 considerably improved the [Ca2+]i recovery and restoration of Δψmit after glutamate and kainate washout and increased cell viability after glutamate exposure. In resting neurons, KB-R7943 induced
a statistically significant decrease in Δψmit. KB-R7943 also depolarized isolated brain mitochondria and slightly inhibited mitochondrial Ca2+ uptake. These findings suggest that mild mitochondrial depolarization and diminution of Ca2+ accumulation in the organelles might contribute to neuroprotective effect of KB-R7943. 相似文献
19.
20.
Dee A. Van Riper Xiao-Liang Chen Errol M. Gould Christopher M. Rembold 《Cell calcium》1996,19(6):501-508
Estimates of [Ca2+]i sensitivity in intact smooth muscle are frequently obtained by measuring [Ca2+]i with indicators such as aequorin or Fura-2. We investigated whether focal in increases in [Ca2+]i could impair such measures of [Ca2+]i sensitivity. Stimulation of swine carotid artery with 10 μM histamine increased aequorin estimated [Ca2+]i, Fura-2 estimated [Ca2+]i and Ca2+ sensitivity without significantly altering the aequorin/Fura-2 ratio (an estimate of [Ca2+]i homogeneity). Subsequent inhibition of Na+/Ca2+ exchange by replacement of Na+ in the PSS with choline+ significantly increased aequorin-estimated [Ca2+]i but only minimally increased Fura-2 estimated [Ca2+]i, myosin light chain (MLC) phosphorylation and force. This resulted in a large increase in the aequorin/Fura-2 ratio, suggesting an increase in [Ca2+] inhomogeneity. Addition of 100 μM histamine to tissues in the choline+ buffer initially increased both aequorin and Fura-2 estimated [Ca2+]i but after 10 min exposure both of the [Ca2+]i estimates declined to pre-histamine levels. Histamine addition significantly increased MLC phosphorylation and force, indicating increased Ca2+ sensitivity, but the aequorin/Fura-2 ratio remained elevated and uncharged from pre-histamine values. These data show that under certain conditions, aequorin and Fura-2 can yield widely differing estimates of [Ca2+]i, and thus can cause misleading assessments of Ca2+ sensitization mechanisms. These discrepancies may arise from inhomogeneous or focal increases in [Ca2+]i which can be evaluated with the aequorin/Fura-2 ratio. 相似文献