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1.
Possible involvement of transient receptor potential ankyrin 1 in Ca2+ signaling via T‐type Ca2+ channel in mouse sensory neurons
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Yuki Nishizawa Kenji Takahashi Naoko Oguma Makoto Tominaga Toshio Ohta 《Journal of neuroscience research》2018,96(5):901-910
T‐type Ca2+ channels and TRPA1 are expressed in sensory neurons and both are associated with pain transmission, but their functional interaction is unclear. Here we demonstrate that pharmacological evidence of the functional relation between T‐type Ca2+ channels and TRPA1 in mouse sensory neurons. Low concentration of KCl at 15 mM (15K) evoked increases of intracellular Ca2+ concentration ([Ca2+]i), which were suppressed by selective T‐type Ca2+ channel blockers. RT‐PCR showed that mouse sensory neurons expressed all subtypes of T‐type Ca2+ channel. The magnitude of 15K‐induced [Ca2+]i increase was significantly larger in neurons sensitive to allylisothiocyanate (AITC, a TRPA1 agonist) than in those insensitive to it, and in TRPA1?/? mouse sensory neurons. TRPA1 blockers diminished the [Ca2+]i responses to 15K in neurons sensitive to AITC, but failed to inhibit 40 mM KCl‐induced [Ca2+]i increases even in AITC‐sensitive neurons. TRPV1 blockers did not inhibit the 15K‐induced [Ca2+]i increase regardless of the sensitivity to capsaicin. [Ca2+]i responses to TRPA1 agonist were enhanced by co‐application with 15K. These pharmacological data suggest the possibility of functional interaction between T‐type Ca2+ channels and TRPA1 in sensory neurons. Since TRPA1 channel is activated by intracellular Ca2+, we hypothesize that Ca2+ entered via T‐type Ca2+ channel activation may further stimulate TRPA1, resulting in an enhancement of nociceptive signaling. Thus, T‐type Ca2+ channel may be a potential target for TRPA1‐related pain. 相似文献
2.
Juan Fan Bo Zhang Hai‐Feng Shu Xiao‐Yu Zhang Xi Wang Fang Kuang Ling Liu Zheng‐Wu Peng Rui Wu Zhuan Zhou Bai‐Ren Wang 《Journal of neuroscience research》2009,87(12):2757-2762
Although abundant evidence indicates mutual regulation between the immune and the central nervous systems, how the immune signals are transmitted to the brain is still an unresolved question. In a previous study we found strong expression of proinflammatory cytokine receptors, including interleukin (IL)‐1 receptor I and IL‐6 receptor α in the rat carotid body (CB), a well‐known arterial chemoreceptor that senses a variety of chemostimuli in the arterial blood. We demonstrated that IL‐1 stimulation increases intracellular calcium ([Ca2+]i) in CB glomus cells, releases ATP, and increases the discharge rate in carotid sinus nerve. To explore the effect of IL‐6 on CB, here we examine the effect of IL‐6 on [Ca2+]i and catecholamine (CA) secretion in rat CB glomus cells. Calcium imaging showed that extracellular application of IL‐6 induced a rise in [Ca2+]i in cultured glomus cells. Amperometry showed that local application of IL‐6 evoked CA release from glomus cells. Furthermore, the CA secretory response to IL‐6 was blocked by 200 μM Cd2+, a well‐known Ca2+ channel blocker. Our experiments provide further evidence for the responsiveness of the CB to proinflammatory cytokines and indicate that the CB might play a role in inflammation sensing and transmission of such information to the brain. © 2009 Wiley‐Liss, Inc. 相似文献
3.
Satoko Soga‐Sakakibara Masakazu Kubota Sinichi Suzuki Tenpei Akita Kazuhiko Narita Kenji Kuba 《The European journal of neuroscience》2010,32(6):948-962
We studied the effects of varying extracellular Ca2+ ([Ca2+]o) and Ca2+ channel density and intracellular loading of Ca2+ chelators on stimulation‐induced rises in intracellular Ca2+ ([Ca2+]i) in frog motor nerve terminals with Ca2+ imaging. The slowly waxing and waning components of rises in [Ca2+]i induced by repetitive tetani were suppressed by blockers of Ca2+ pumps of the endoplasmic reticulum (thapsigargin and cyclopiazonic acid) and a blocker of ryanodine receptors [8‐(N,N‐diethylamino)octyl 3,4,5‐trimethoxybenzoate hydrochloride] without affecting the initial quickly‐rising component, thus reflecting the priming (and then subsequent rapid activation) and inactivation phases of Ca2+‐induced Ca2+ release (CICR) from the endoplasmic reticulum. A short tetanus‐induced rise in [Ca2+]i was proportional to [Ca2+]o, whereas the component of CICR was non‐linearly related to [Ca2+]o with saturation at 0.9 mm . The progressive blockade of Ca2+ channels by ω‐conotoxin GVIA caused proportional decreases in CICR and short tetanus‐induced [Ca2+]i rises. Intracellular loading of BAPTA and EGTA reduced the magnitude of CICR as well as short tetanus‐induced rises in [Ca2+]i with a greater effect of BAPTA than EGTA on CICR. The time to peak and the half decay time of CICR were prolonged by a low [Ca2+]o or Ca2+ channel blocker or [Ca2+]i chelators. These results suggest that ryanodine receptors sense the high [Ca2+]i transient following single action potentials for triggering CICR, whereas the priming and inactivation processes of CICR sense a slower, persisting rise in [Ca2+]i during and after action potential trains. A model is presented that includes CICR activation in elementary units. 相似文献
4.
Message encoding for three isoforms of somatostatin (SS) peptides, SS‐14, goldfish brain (gb)SS‐28 and [Pro2]SS‐14, are expressed in goldfish hypothalamus and pituitary tissues. All three native goldfish SSs are active in reducing basal and stimulated growth hormone (GH) responses in cultured goldfish pituitary cells, although with different potencies and efficacies. In the present study, we examined the effects of these three endogenous SSs on electrophysiological properties of goldfish somatotrophs and their physiological relevance. Voltage‐sensitive K+, Ca2+ and Na+ channels in identified goldfish somatotrophs in primary culture were isolated using whole‐cell, amphotericin B‐perforated patch‐clamp techniques. None of the three SSs affected Na+ currents but all three SSs increased maximal K+ current magnitude, with SS‐14 being the most effective. [Pro2]SS14 did not affect Ba2+ currents through voltage‐sensitive Ca2+ channels but SS14 decreased the magnitude of early and late Ba2+ currents, whereas gbSS‐28 reduced that of the late Ba2+ current. Under current‐clamp conditions, SS14 and gbSS28 attenuated evoked action potential magnitudes by 34% and 18%, respectively, although [Pro2]SS14 had no effects. However, all three SSs decreased basal intracellular Ca2+ levels ([Ca2+]i) and suppressed basal GH release. These data suggest that, although the ability of SS‐14 and gbSS‐28 to decrease basal [Ca2+]i and GH release can be explained, at least in part, by their attenuating effects on cell excitability and current flow through voltage‐sensitive Ca2+channels, [Pro2]SS14‐induced reduction in GH responses and [Ca2+]i cannot be explained by changes in Ca2+ channel properties. 相似文献
5.
Minoru Sato 《Brain research》1997,768(1-2)
The effects of the removal of extracellular Ca2+ on the responses of cytosolic concentrations of Ca2+ ([Ca2+]i) to acidic stimuli, a protonophore carbonyl cyanide p-trifluoromethoxyphenylhydrazone (FCCP) and an organic acid acetate, were examined in clusters of cultured carotid body glomus cells of adult rabbits using fura-2 microfluorometry. Application of FCCP (1 μM) induced an increase in [Ca2+]i (mean±S.E.M., 108±14%). After withdrawal of the protonophore the increased [Ca2+]i returned slowly to a resting level. The [Ca2+]i response was attenuated by an inorganic Ca2+ channel antagonist Ni2+ (2 mM) by 81±4%, and by an L-type voltage-gated Ca2+ channel antagonist D600 (10 μM) by 53±13%. The removal of extracellular Ca2+ eliminated the [Ca2+]i response in 71% of the tested cells (n=17), and depressed it by 68±6% in the rest. Recovery following stimulation with FCCP in the absence of Ca2+ reversibly produced a rapid and large rise in [Ca2+]i, referred to as a [Ca2+]i rise after Ca2+-free/FCCP. The magnitude of a [Ca2+]i rise after Ca2+-free/FCCP (285±28%, P<0.05) was larger than that of an increase in [Ca2+]i induced by FCCP in the presence of Ca2+ and had a correlation with the intensity of the suppression of the [Ca2+]i response by Ca2+ removal. A [Ca2+]i rise after Ca2+-free/FCCP was inhibited mostly by D600. Similarly, recovery following exposure to acetate in the absence of Ca2+ caused a rise in [Ca2+]i, referred to as a [Ca2+]i rise after Ca2+-free/acetate which was sensitive to D600. The magnitude of the [Ca2+]i rise was larger than that of a change in [Ca2+]i caused by acetate in the presence of Ca2+. These results suggest that FCCP-induced increase in [Ca2+]i was, in most cells, due to Ca2+ influx via L-type voltage-gated Ca2+ channels and, in some cells, due to both Ca2+ influx and Ca2+ release from internal Ca2+ pool. The removal of extracellular Ca2+ might modify [Ca2+]i responses to acidic stimuli, causing [Ca2+]i rises after Ca2+-free/acidic stimuli which involve mostly L-type Ca2+ channels. 相似文献
6.
Intramyofiber accumulation of β‐amyloid fragments (Aβ) is a pathologic hallmark of inclusion‐body myositis (IBM), a progressive skeletal muscle disorder. We investigated the temporal pattern of alterations in the resting cytoplasmic [Ca2+] ([Ca2+]i) as well as the depolarization‐evoked Ca2+ release from the sarcoplasmic reticulum in skeletal muscle from transgenic mice expressing human βAPP (MCK‐βAPP). MCK‐βAPP mice show an age‐dependent increase in [Ca2+]i along with a reduction in depolarization‐evoked Ca2+ release, which appear well before the other reported aspects of IBM, such as inclusion formation, inflammation, centralized nuclei, atrophy, and skeletal muscle weakness. In the young MCK‐βAPP animals the increase in resting [Ca2+]i can be attributed largely to Ca2+ influx through nifedipine‐sensitive Ca2+ channels. In the adult MCK‐βAPP mice, in addition to the nifedipine‐sensitive pathway, there is also a substantial contribution by the intracellular compartments to the increase in [Ca2+]i. These results suggest that β‐amyloid‐induced disuption of Ca2+ handling may represent an early event in the pathogenesis of IBM. Muscle Nerve, 2010 相似文献
7.
Peter S. Freestone Kenny K. H. Chung Ezia Guatteo Nicola B. Mercuri Louise F.B. Nicholson Janusz Lipski 《The European journal of neuroscience》2009,30(10):1849-1859
Rotenone is a toxin used to generate animal models of Parkinson’s disease; however, the mechanisms of toxicity in substantia nigra pars compacta (SNc) neurons have not been well characterized. We have investigated rotenone (0.05–1 μm ) effects on SNc neurons in acute rat midbrain slices, using whole‐cell patch‐clamp recording combined with microfluorometry. Rotenone evoked a tolbutamide‐sensitive outward current (94 ± 15 pA) associated with increases in intracellular [Ca2+] ([Ca2+]i) (73.8 ± 7.7 nm ) and intracellular [Na+] (3.1 ± 0.6 mm ) (all with 1 μm ). The outward current was not affected by a high ATP level (10 mm ) in the patch pipette but was decreased by Trolox. The [Ca2+]i rise was abolished by removing extracellular Ca2+, and attenuated by Trolox and a transient receptor potential M2 (TRPM2) channel blocker, N‐(p‐amylcinnamoyl) anthranilic acid. Other effects included mitochondrial depolarization (rhodamine‐123) and increased mitochondrial reactive oxygen species (ROS) production (MitoSox), which was also abolished by Trolox. A low concentration of rotenone (5 nm ) that, by itself, did not evoke a [Ca2+]i rise resulted in a large (46.6 ± 25.3 nm ) Ca2+ response when baseline [Ca2+]i was increased by a ‘priming’ protocol that activated voltage‐gated Ca2+ channels. There was also a positive correlation between ‘naturally’ occurring variations in baseline [Ca2+]i and the rotenone‐induced [Ca2+]i rise. This correlation was not seen in non‐dopaminergic neurons of the substantia nigra pars reticulata (SNr). Our results show that mitochondrial ROS production is a key element in the effect of rotenone on ATP‐gated K+ channels and TRPM2‐like channels in SNc neurons, and demonstrate, in these neurons (but not in the SNr), a large potentiation of rotenone‐induced [Ca2+]i rise by a small increase in baseline [Ca2+]i. 相似文献
8.
9.
Tadayuki Honda Naoshi Fujiwara Takashi Abe Toshiro Kumanishi Megumu Yoshimura Koki Shimoji 《Brain research》1994,666(2)
Prior mechanical brain microinjury has been found to have a preventive effect on brain ischemia. To investigate the mechanism responsible for this, the effect of mechanical brain injury on changes in intracellular free Ca2+ concentration ([Ca2+]i) in response to ischemic insult was studied in mouse hippocampal slices. The mechanical injury was made by inserting a 25G hypodermic needle into the CA1 region of the hippocampus in mice anesthetized with pentobarbital. Sagittal slices of the hippocampus were prepared two hours, and 1, 3, 7, and 14 days after the brain injury. Changes in [Ca2+]i in the slices by oxygen-glucose deprivation were analyzed from fluorescence images, using fura-2. Increases in [Ca2+]i induced by oxygen-glucose deprivation were inhibited in the vicinity of the injury 1 and 3 days after injury. [Ca2+]i levels were lower in the posterior side from the injury than in the anterior side 1 and 3 days after injury. No significantly regional differences in [Ca2+]i responses were found 2 h or 7 and 14 days after the injury. Membrane potential and membrane resistance of CA1 neurons in the vicinity of the injury measured 1 day after the injury were not significantly altered in comparison with non-injured slices. These results indicate that mechanical brain injury inhibits ischemic [Ca2+]i increase. This inhibition may be induced not only by damage of the presynaptic fibers projecting to the CA1 neurons but also by the other certain factor(s) that prevent [Ca2+]i increase, and it appears to be related to the protective effect of prior mechanical injury against ischemic neuronal damage. 相似文献
10.
To investigate the correlation between neural activity and intracellular Ca2+ ([Ca2+]i) mobilization in immature and adult brain during ischemia (hypoxia and glucose deprivation) and deprivation of glucose, hippocampal slices were prepared from 7-, 10-day-old and adult rats. Population spikes (PS) and antidromic responses (AR) were recorded in the pyramidal cell layer of the CA1 area as an index of neural function. [Ca2+]i mobilization of the stratum radiatum in the CA1 area was measured using the fluorescent dye fura-2 AM. The rise in [Ca2+]i occurred earlier in the adult animal and the decay times for the orthodromic PS and antidromic responses were shorter in the adult during ischemia. The field potentials and antidromic responses decreased substantially prior to the elevation of [Ca2+]i in both developing and adult brains. Furthermore, ATP levels decreased substantially before the elevation of [Ca2+]i during ischemia. These results suggest that neural activity and intracellular Ca2+ homeostasis in the immature rats brain are more resistant to energy failure than adult rats and that neuronal activity in the developing and adult brain is impaired initially by energy depletion during ischemia. In the immature animal, during glucose deprivation, the antidromic responses were slowly decayed or even failed to extinguish and [Ca2+]i levels were maintained for a longer period or even failed to rise in spite of the rapid loss of PS. Furthermore, ATP levels were well preserved at the time of PS loss. These results agree well with our previous reports showing that glucose plays an important role in the preservation of synaptic transmission in addition to its major function as an energy substrate. 相似文献
11.
12.
α motor neurons (MNs) are a target of the environmental neurotoxicant methylmercury (MeHg), accumulating MeHg and subsequently degenerating. In mouse spinal cord MN cultures, MeHg increased intracellular Ca2+ [Ca2+]i; the AMPA receptor (AMPAR) antagonist CNQX delayed the increase in [Ca2+]i, implicating the role of AMPARs in this response. Here we used human induced pluripotent stem cell-derived MNs (hiPSC-MNs), to characterize the role of MN AMPARs in MeHg neurotoxicity. Acute exposure to MeHg (0.1, 0.2, 0.5, 1 and 1.5 μM), fura-2 microfluorimetry, and a standard cytotoxicity assay, were used to examine MN regulation of [Ca2+]i, and cytotoxicity, respectively. Contribution of Ca2+-permeable and impermeable AMPARs was compared using either CNQX, or the Ca2+-permeable AMPAR antagonist N-acetyl spermine (NAS). MeHg-induced cytotoxicity was evaluated following a 24 h delay subsequent to 1 h exposure of hiPSC-MNs. MeHg caused a characteristic biphasic increase in [Ca2+]i, the onset of which was concentration-dependent; higher MeHg concentrations hastened onset of both phases. CNQX significantly delayed MeHg’s effect on onset time of both phases. In contrast, NAS significantly delayed only the 2nd phase increase in fura-2 fluorescence. Exposure to MeHg for 1 h followed by a 24 h recovery period caused a concentration-dependent incidence of cell death. These results demonstrate for the first time that hiPSC-derived MNs are highly sensitive to effects of MeHg on [Ca2+]i, and cytotoxicity, and that both Ca2+-permeable and impermeable AMPARs contribute the elevations in [Ca2+]i. 相似文献
13.
Yoon Hee Chung Chung-min Shin Myeung Ju Kim Dong Hoon Shin Young Bok Yoo Choong Ik Cha 《Brain research》2001,919(2):247
In the present study, we have investigated the spatial and temporal distribution of voltage-gated calcium channels in the gerbil model of global cerebral ischemia using immunohistochemistry. Distinct localizations of P-type (α1A), N-type (α1B), and L-type (α1C and α1D) Ca2+ channels were observed in the hippocampus at days 1–5 after ischemic injury. However, increased expression of N-type Ca2+ channels was detectable in brain regions vulnerable to ischemia only at days 2 and 3 after ischemic injury. The pyramidal cell bodies of CA1-3 areas and the granule cell bodies of the dentate gyrus were intensely stained at days 2 and 3 following ischemic injury. Transient changes in N-type Ca2+ channel expression were also observed in the affected cerebral cortex and striatum at days 2 and 3 after ischemic injury. Although the present study has not addressed the multiple mechanisms contributing to the intracellular free Ca2+ concentration ([Ca2+]i) increase in the ischemic brain, the first demonstration of the transient increase in N-type Ca2+ channels may prove useful for future investigations. 相似文献
14.
Cristina Velzquez‐Marrero Edward E. Custer Hctor Marrero Sonia Ortiz‐Miranda Jos R. Lemos 《Journal of neuroendocrinology》2020,32(4)
Depolarisation‐secretion coupling is assumed to be dependent only on extracellular calcium ([Ca2+]o). Ryanodine receptor (RyR)‐sensitive stores in hypothalamic neurohypophysial system (HNS) terminals produce sparks of intracellular calcium ([Ca2+]i) that are voltage‐dependent. We hypothesised that voltage‐elicited increases in intraterminal calcium are crucial for neuropeptide secretion from presynaptic terminals, whether from influx through voltage‐gated calcium channels and/or from such voltage‐sensitive ryanodine‐mediated calcium stores. Increases in [Ca2+]i upon depolarisation in the presence of voltage‐gated calcium channel blockers, or in the absence of [Ca2+]o, still give rise to neuropeptide secretion from HNS terminals. Even in 0 [Ca2+]o, there was nonetheless an increase in capacitance suggesting exocytosis upon depolarisation. This was blocked by antagonist concentrations of ryanodine, as was peptide secretion elicited by high K+ in 0 [Ca2+]o. Furthermore, such depolarisations lead to increases in [Ca2+]i. Pre‐incubation with BAPTA‐AM resulted in > 50% inhibition of peptide secretion elicited by high K+ in 0 [Ca2+]o. Nifedipine but not nicardipine inhibited both the high K+ response for neuropeptide secretion and intraterminal calcium, suggesting the involvement of CaV1.1 type channels as sensors in voltage‐induced calcium release. Importantly, RyR antagonists also modulate neuropeptide release under normal physiological conditions. In conclusion, our results indicate that depolarisation‐induced neuropeptide secretion is present in the absence of external calcium, and calcium release from ryanodine‐sensitive internal stores is a significant physiological contributor to neuropeptide secretion from HNS terminals. 相似文献
15.
Chessa S. Scullin Michael C. Wilson L. Donald Partridge 《The European journal of neuroscience》2010,31(5):817-826
Presynaptic Ca2+ influx pathways, cytoplasmic Ca2+ buffering proteins and Ca2+ extrusion processes undergo considerable change during the first postnatal month in rodent neurons. These changes may be critical in establishing short‐term plasticity at maturing presynaptic terminals where neurotransmitter release is directly dependent on the dynamics of cytoplasmic residual Ca2+ ([Ca2+]res). In particular, the robust paired‐pulse facilitation characteristic of adult neurons is almost entirely lacking in newborns. To examine developmental changes in processes controlling [Ca2+]res, we measured the timecourse of [Ca2+]res decay in presynaptic terminals of Schaffer collateral to CA1 synapses in acute hippocampal slices following single and paired orthodromic stimuli in the stratum radiatum. Developmental changes were observed in both the rise time and slow exponential decay components of the response to single stimuli such that this decay was larger and faster in the adult. Furthermore, we observed a greater caffeine‐sensitive basal Ca2+ store, which was differentially affected when active uptake into the endoplasmic reticulum was blocked, in the presynaptic fields of the Schaffer collateral to CA1 terminals of P6 and younger mice when compared to adults. These transitions in [Ca2+]res dynamics occurred gradually over the first weeks of postnatal life and correlated with changes in short‐term plasticity. 相似文献
16.
Yutaka Shindo Ai Fujimoto Kohji Hotta Koji Suzuki Kotaro Oka 《Journal of neuroscience research》2010,88(14):3125-3132
Excess administration of glutamate is known to induce Ca2+ overload in neurons, which is the first step in excitotoxicity. Although some reports have suggested a role for Mg2+ in the excitotoxicity, little is known about its actual contribution. To investigate the role of Mg2+ in the excitotoxicity, we simultaneously measured intracellular Ca2+ and Mg2+, using fluorescent dyes, Fura red, a fluorescent Ca2+ probe, and KMG‐104, a highly selective fluorescent Mg2+ probe developed by our group, respectively. Administration of 100 μM glutamate supplemented with 10 μM glycine to rat hippocampal neurons induced an increase in intracellular Mg2+ concentration ([Mg2+]i). Extracellular Mg2+ was not required for this glutamate‐induced increase in [Mg2+]i, and no increase in intracellular Ca2+ concentration ([Ca2+]i) or [Mg2+]i was observed in neurons in nominally Ca2+‐free medium. Application of 5 μM carbonyl cyanide p‐(trifluoromethoxy) phenylhydrazone (FCCP), an uncoupler of mitochondrial inner membrane potential, also elicited increases in [Ca2+]i and [Mg2+]i. Subsequent administration of glutamate and glycine following FCCP treatment did not induce a further increase in [Mg2+]i but did induce an additive increase in [Ca2+]i. Moreover, the glutamate‐induced increase in [Mg2+]i was observed only in mitochondria localized areas. These results support the idea that glutamate is able to induced Mg2+ efflux from mitochondria to the cytosol. Furthermore, pretreatment with Ru360, an inhibitor of the mitochondrial Ca2+ uniporter, prevented this [Mg2+]i increase. These results indicate that glutamate‐induced increases in [Mg2+]i result from the Mg2+ release from mitochondria and that Ca2+ accumulation in the mitochondria is required for this Mg2+ release. © 2010 Wiley‐Liss, Inc. 相似文献
17.
Objective This paper aimed to investigate the relationship between up‐regulation of L‐type calcium channels and altered motility disorder in a rat model of irritable bowel syndrome (IBS). Methods Male Sprague–Dawley rats were subjected to neonatal maternal separation (NMS) from postnatal day 2–14 or normal handling (NH), and used when weighted 250–300 g. Colonic smooth muscle contractions was studied in an organ bath system. L‐type Ca2+ channel α1c subunit expression in smooth muscles from rat colon were studied by immunofluorescence and Western blotting analysis. The intracellular calcium concentration ([Ca2+]i) of enzymatically isolated single colonic smooth muscle cell was studied with laser confocal fluorescent microscopy. Results The fecal pellets during 1 h water avoidance stress (WAS) were significantly increased; the amplitude of spontaneous contractions and contractions induced by Bay K 8644 (10 nm –1 μm ), KCl (10–60 mm ) and ACh (100 nm –10 μm ) were significantly increased in NMS rats, when comparing with that of NH rats. [Ca2+]i induced by Bay K 8644 (1 μm ), KCl (40 mm ), and ACh (10 μm ) significantly increased in muscle cells of NMS rats than NH rats. Further, α1c protein expression was significantly up‐regulated in colonic smooth muscle of NMS rats than NH rats. Conclusion These results suggest that NMS lead to up‐regulation of L‐type Ca2+ channels expression in the colon, which contributes to the colonic motility disorder. Our findings provide direct evidence to help understanding the underlying mechanism of chronic stress‐induced colonic motility disorder in IBS. 相似文献
18.
Minoru Sato 《Brain research》1999,828(1-2)
Effect of the removal of extracellular Ca2+ on the response of cytosolic concentrations of Ca2+ ([Ca2+]i) to ouabain, an Na+/K+ exchanger antagonist, was examined in clusters of cultured carotid body glomus cells of adult rabbits using fura-2AM and microfluorometry. Application of ouabain (10 mM) induced a sustained increase in [Ca2+]i (mean±S.E.M.; 38±5% increase, n=16) in 55% of tested cells (n=29). The ouabain-induced [Ca2+]i increase was abolished by the removal of extracellular Na+. D600 (50 μM), an L-type voltage-gated Ca2+ channel antagonist, inhibited the [Ca2+]i increase by 57±7% (n=4). Removal of extracellular Ca2+ eliminated the [Ca2+]i increase, but subsequent washing out of ouabain in Ca2+-free solution produced a rise in [Ca2+]i (62±8% increase, n=6, P<0.05), referred to as a [Ca2+]i rise after Ca2+-free/ouabain. The magnitude of the [Ca2+]i rise was larger than that of ouabain-induced [Ca2+]i increase. D600 (5 μM) inhibited the [Ca2+]i rise after Ca2+-free/ouabain by 83±10% (n=4). These results suggest that ouabain-induced [Ca2+]i increase was due to Ca2+ entry involving L-type Ca2+ channels which could be activated by cytosolic Na+ accumulation. Ca2+ removal might modify the [Ca2+]i response, resulting in the occurrence of a rise in [Ca2+]i after Ca2+-free/ouabain which mostly involved L-type Ca2+ channels. 相似文献
19.
A. Hernández-Cruz M. Díaz-Muñoz M. Gómez-Chavarín R. Canñedo-Merino D. A. Protti A. L. Escobar J. Sierralta B. A. Suárez-Isla 《The European journal of neuroscience》1995,7(8):1684-1699
The most compelling evidence for a functional role of caffeine-sensitive intracellular Ca2+ reservoirs in nerve cells derives from experiments on peripheral neurons. However, the properties of their ryanodine receptor calcium release channels have not been studied. This work combines single-cell fura-2 microfluorometry, [3 H]ryanodine binding and recording of Ca2+ release channels to examine calcium release from these intracellular stores in rat sympathetic neurons from the superior cervical ganglion. Intracellular Ca2+ measurements showed that these cells possess caffeine-sensitive intracellular Ca2+ stores capable of releasing the equivalent of 40% of the calcium that enters through voltage-gated calcium channels. The efficiency of caffeine in releasing Ca2+ showed a complex dependence on [Ca2+]i. Transient elevations of [Ca2+]i by 50–500 nM were facilitatory, but they became less facilitatory or depressing when [Ca2+]i reached higher levels. The caffeine-induced Ca2+ release and its dependence on [Ca2+]i was further examined by [3 H]ryanodine binding to ganglionic microsomal membranes. These membranes showed a high-affinity binding site for ryanodine with a dissociation constant (KD= 10 nM) similar to that previously reported for brain microsomes. However, the density of [3H]ryanodine binding sites (Bmax= 2.06 pmol/mg protein) was at least three-fold larger than the highest reported for brain tissue. [3 H]Ryanodine binding showed a sigmoidal dependence on [Ca2+] in the range 0.1–10 μM that was further increased by caffeine. Caffeine-dependent enhancement of [3 H]ryanodine binding increased and then decreased as [Ca2+] rose, with an optimum at [Ca2+] between 100 and 500 nM and a 50% decrease between 1 and 10 μM. At 100 μM [Ca2+], caffeine and ATP enhanced [3 H]ryanodine binding by 35 and 170% respectively, while binding was reduced by >90% with ruthenium red and MgCl2. High-conductance (240 pS) Ca2+ release channels present in ganglionic microsomal membranes were incorporated into planar phospholipid bilayers. These channels were activated by caffeine and by micromolar concentrations of Ca2+ from the cytosolic side, and were blocked by Mg2+ and ruthenium red. Ryanodine (2 μM) slowed channel gating and elicited a long-lasting subconductance state while 10 mM ryanodine closed the channel with infrequent opening to the subconductance level. These results show that the properties of the ryanodine receptor/Ca2+ release channels present in mammalian peripheral neurons can account for the properties of caffeine-induced Ca2+ release. Our data also suggest that the release of Ca2+ by caffeine has a bell-shaped dependence on Ca2+ in the physiological range of cytoplasmic [Ca2+]. 相似文献
20.
Henrike Hartmann Anne Eckert Hans Förstl Walter E. Müller 《European archives of psychiatry and clinical neuroscience》1994,243(5):218-223
Summary Several studies suggest that alterations of cytosolic free calcium concentration ([Ca2+]i) are involved in the pathophysiology of aging and Alzheimer's disease (AD). However, only few data are presently available giving detailed information about specific characteristics of age-related or AD-specific changes in cellular Ca2+-homeostasis. To allow a comprehensive evaluation of age-related changes in [Ca2+]i, we performed parallel investigations in central mouse brain cells and mouse spleen lymphocytes of young and aged animals and also in human lymphocytes and granulocytes of young and aged donors and additionally of AD patients. In aged animals, basal [Ca2+]i was decreased in brain cells but increased in spleen lymphocytes. No age-related alterations in baseline [Ca2+]i was found in human lymphocytes or granulocytes. However, comparison of activation-induced rise in [Ca2+]i revealed parallel age-related changes in the different cell-types investigated. The increase in [Ca2+]i after depolarization of mouse brain cells with KCl and after stimulation of mouse lymphocytes with phytohaemagglutinin (PHA) was significantly impaired in aged animals. Moreover, activation of human lymphocytes with PHA also revealed a reduced increase in [Ca2+]i in cells of aged donors. In lymphocytes of AD-patients there was a tendency to higher basal [Ca2+]i compared to their aged matched controls, but no specific alterations in [Ca2+]i could be found after stimulation with PHA. Also no age-related or AD-specific changes were found in granulocytes after stimulation with N-fomyl-methionyl-leucyl-phenylalanine (fMLP). Since K+- and PHA-induced rise in [Ca2+]i is mainly mediated by Ca2+-influx, whereas fMLP-stimulated rise in [Ca2+]i is mainly due to intracellular Ca2+-release, our findings might indicate that age-related disturbances of Ca2+-homeostasis especially affect mechanisms involved in Ca2+-influx. The corresponding age-related alterations in mouse brain cells, mouse spleen lymphocytes and human lymphocytes after cell activation suggest a similar impairment of Ca2+-homeostatis in these cells and might justify the speculation that Ca2+-homeostasis in the aged human brain is affected in a comparable fashion. 相似文献