共查询到20条相似文献,搜索用时 31 毫秒
1.
E. I. Khoroshavina M. V. Dubinin V. N. Samartsev 《Biochemistry (Moscow) Supplemental Series A: Membrane and Cell Biology》2016,10(4):287-293
The effects of hydrophobic and hydrophilic bile acids as inducers of Ca2+-dependent permeability of the inner membrane were studied on isolated liver mitochondria. It is shown that in the absence of the inorganic phosphate (Pi)–a modulator of the mitochondrial pore–hydrophobic bile acids (lithocholic, deoxycholic, chenodeoxycholic) at concentrations of 20–50 μM, as well as a hydrophilic cholic acid at a concentration of 800 μM, induce swelling of liver mitochondria loaded with Ca2+. This effect is completely eliminated by a specific inhibitor of mitochondrial pore cyclosporin A (CsA). The effect of the bile acids as inducers of Ca2+-dependent CsA-sensitive mitochondrial pore is not associated with the modulation of the Pi effects. In contrast to other tested bile acids, a hydrophilic ursodeoxycholic acid (UDCA) at a concentration of 400 μM is able to induce Ca2+-dependent CsA-sensitive pore opening in liver mitochondria only in the presence of Pi or in the absence of potassium chloride in the incubation medium. In the presence of potassium chloride but in the absence of Pi, UDCA effects associated with the induction of the inner membrane permeability (swelling of mitochondria, drop in Δψ, and Ca2+ release from the matrix) are also observed in the presence of CsA. This Ca2+-dependent permeability of the inner membrane, in contrast to the “classical” CsA-sensitive pore, is characterized by a lower intensity of the mitochondrial swelling, a total drop in Δψ, and Ca2+ release from the matrix and is blocked by Pi. We suggest that the induction of the CsA-insensitive permeability in the inner mitochondrial membrane by UDCA is associated with activation of electrophoretic influx of K+ into the matrix and Ca2+ release from the matrix in exchange to H+. The effect of Pi as a blocker of such permeability is discussed. 相似文献
2.
The effect of taurine on the ATP-dependent mitochondrial swelling that characterizes the activity of mitochondrial ATP-dependent K+ channel and the formation of Ca2+-dependent pores, different in sensitivity to cyclosporin A, has been studied in rat liver mitochondria. It has been shown that taurine in micromolar concentrations (0.5–125 μM) stimulates the energy-dependent swelling of mitochondria. Taurine in physiological concentrations (0.5–20 mM) has no effect on the ATP-dependent swelling and the formation of cyclosporin A-insensitive Pal/Ca2+-activated pore in mitochondria. Taurine in these concentrations increased the rate of cyclosporin A-sensitive swelling of mitochondria induced by Ca2+ and Pi and reduced the Ca2+ capacity of mitochondria. The different effects of physiological taurine concentrations on the ATP-dependent transport of K+ and Ca2+ ions in mitochondrial membranes as compared with cell membranes are discussed. 相似文献
3.
The large inner membrane electrochemical driving force and restricted volume of the matrix confer unique constraints on mitochondrial ion transport. Cation uptake along with anion and water movement induces swelling if not compensated by other processes. For mitochondrial Ca2+ uptake, these include activation of countertransporters (Na+/Ca2+ exchanger and Na+/H+ exchanger) coupled to the proton gradient, ultimately maintained by the proton pumps of the respiratory chain, and Ca2+ binding to matrix buffers. Inorganic phosphate (Pi) is known to affect both the Ca2+ uptake rate and the buffering reaction, but the role of anion transport in determining mitochondrial Ca2+ dynamics is poorly understood. Here we simultaneously monitor extra- and intra-mitochondrial Ca2+ and mitochondrial membrane potential (ΔΨm) to examine the effects of anion transport on mitochondrial Ca2+ flux and buffering in Pi-depleted guinea pig cardiac mitochondria. Mitochondrial Ca2+ uptake proceeded slowly in the absence of Pi but matrix free Ca2+ ([Ca2+]mito) still rose to ∼50 μm. Pi (0.001–1 mm) accelerated Ca2+ uptake but decreased [Ca2+]mito by almost 50% while restoring ΔΨm. Pi-dependent effects on Ca2+ were blocked by inhibiting the phosphate carrier. Mitochondrial Ca2+ uptake rate was also increased by vanadate (Vi), acetate, ATP, or a non-hydrolyzable ATP analog (AMP-PNP), with differential effects on matrix Ca2+ buffering and ΔΨm recovery. Interestingly, ATP or AMP-PNP prevented the effects of Pi on Ca2+ uptake. The results show that anion transport imposes an upper limit on mitochondrial Ca2+ uptake and modifies the [Ca2+]mito response in a complex manner. 相似文献
4.
The excitotoxicity of glutamate is believed to be mediated by sustained increase in the cytosolic Ca2+ concentration. Mitochondria play a vital role in buffering the cytosolic calcium overload in stimulated neurons. Here we have studied the glutamate induced Ca2+ signals in cortical brain slices under physiological conditions and the conditions that modify the mitochondrial functions. Exposure of slices to glutamate caused a rapid increase in [Ca2+]i followed by a slow and persistently rising phase. The rapid increase in [Ca2+]i was mainly due to influx of Ca2+ through the N-methyl-D-aspartate (NMDA) receptor channels. Glutamate stimulation in the absence of Ca2+ in the extracellular medium elicited a small transient rise in [Ca2+]i which can be attributed to the mobilization of Ca2+ from IP3 sensitive endoplasmic reticulum pools consequent to activation of metabotropic glutamate receptors. The glutamate induced Ca2+ influx was accompanied by depolarization of the mitochondrial membrane, which was inhibited by ruthenium red, the blocker of mitochondrial Ca2+ uniporter. These results imply that mitochondria sequester the Ca2+ loaded into the cytosol by glutamate stimulation. Persistent depolarization of mitochondrial membrane observed in presence of extracellular Ca2+ caused permeability transition and released the sequestered Ca2+ which is manifested as slow rise in [Ca2+]i. Protonophore carbonyl cyanide m-chlorophenyl-hydrazone (CCCP) depolarized the mitochondrial membrane and enhanced the glutamate induced [Ca2+]i response. Contrary to this, treatment of slices with mitochondrial inhibitor oligomycin or ruthenium red markedly reduced the [Ca2+]i response. Combined treatment with oligomycin and rotenone further diminished the [Ca2+]i response and also abolished the CCCP mediated rise in [Ca2+]i. However, rotenone alone had no effect on glutamate induced [Ca2+]i response. These changes in glutamate-induced [Ca2+]i response could not be explained on the basis of deficient mitochondrial Ca2+ sequestration or ATP dependent Ca2+ buffering. The mitochondrial inhibitors reduced the cellular ATP/ADP ratio, however, this would have restrained the ATP dependent Ca2+ buffering processes leading to elevation of [Ca2+]i. In contrast our results showed repression of Ca2+ signal except in case of CCCP which drastically reduced the ATP/ADP ratio. It was inferred that, under the conditions that hamper the Ca2+ sequestering ability of mitochondria, the glutamate induced Ca2+ influx could be impeded. To validate this, influx of Mn2+ through ionotropic glutamate receptor channel was monitored by measuring the quenching of Fura-2 fluorescence. Treatment of slices with oligomycin and rotenone prior to glutamate exposure conspicuously reduced the rate of glutamate induced fluorescence quenching as compared to untreated slices. Thus our data establish that the functional status of mitochondria can modify the activity of ionotropic glutamate receptor and suggest that blockade of mitochondrial Ca2+ sequestration may desensitize the NMDA receptor operated channel. 相似文献
5.
Differential regulation of intracellular calcium oscillations by mitochondria and gap junctions 总被引:1,自引:0,他引:1
Fluctuations of intracellular Ca2+ ([Ca2+]i) regulate a variety of cellular functions. The classical Ca2+ transport pathways in the endoplasmic reticulum (ER) and plasma membrane are essential to [Ca2+]i oscillations. Although mitochondria have recently been shown to absorb and release Ca2+ during G protein-coupled receptor (GPCR) activation, the role of mitochondria in [Ca2+]i oscillations remains to be elucidated. Using fluo-3-loaded human teratocarcinoma NT2 cells, we investigated the regulation
of [Ca2+]i oscillations by mitochondria. Both the muscarinic GPCR agonist carbachol and the ER Ca2+-adenosine triphosphate inhibitor thapsigargin (Tg) induced [Ca2+]i oscillations in NT2 cells. The [Ca2+]i oscillations induced by carbachol were unsynchronized among individual NT2 cells; in contrast, Tg-induced oscillations were
synchronized. Inhibition of mitochondrial functions with either mitochondrial blockers or depletion of mitochondrial DNA eliminated
carbachol—but not Tg-induced [Ca2+]i oscillations. Furthermore, carbachol-induced [Ca2+]i oscillations were partially restored to mitochondrial DNA-depleted NT2 cells by introduction of exogenous mitochondria. Treatment
of NT2 cells with gap junction blockers prevented Tg-induced but not carbachol-induced [Ca2+]i oscillations. These data suggest that the distinct patterns of [Ca2+]i oscillations induced by GPCR and Tg are differentially modulated by mitochondria and gap junctions. 相似文献
6.
Konstantin N. Belosludtsev Natalia V. Belosludtseva Eugeny Yu Talanov Kirill S. Tenkov Vlada S. Starinets Alexey V. Agafonov Lyubov L. Pavlik Mikhail V. Dubinin 《生物化学与生物物理学报:生物膜》2019,1861(1):288-297
The paper considers the effects of bedaquiline (BDQ), an antituberculous preparation of the new generation, on rat liver mitochondria. It was shown that 50?μM BDQ inhibited mitochondrial respiration measured with substrates of complexes I and II (glutamate/malate and succinate/rotenone systems respectively) in the states V3 and VDNP. At the same time, at concentrations below 50?μM, BDQ slightly stimulated respiration with substrates of complex I in the state V2. BDQ was also found to suppress, in a dose-dependent manner, the activity of complex II and the total activity of complexes II?+?III of the mitochondrial transport chain. It was discovered that at concentrations up to 10?μM, BDQ inhibited H2O2 production in mitochondria. BDQ (10–50?μM) suppressed the opening of Ca2+-dependent CsA-sensitive mitochondrial permeability transition pore. The latter was revealed experimentally as the inhibition of Ca2+/Pi-dependent swelling of mitochondria, suppression of cytochrome c release, and an increase in the Ca2+ capacity of the organelles. BDQ also decreased the rate of mitochondrial energy-dependent K+ transport, which was evaluated by the energy-dependent swelling of mitochondria in a K+ buffer and DNP-induced K+ efflux from the organelles. The possible mechanisms of BDQ effect of rat liver mitochondria are discussed. 相似文献
7.
Takenori Yamamoto Yuya Yoshimura Akiko Yamada Shunichi Gouda Kikuji Yamashita Naoshi Yamazaki Masatoshi Kataoka Toshihiko Nagata Hiroshi Terada Yasuo Shinohara 《Journal of bioenergetics and biomembranes》2008,40(6):619-623
For induction of the mitochondrial permeability transition (PT) by Ca2+, the addition of a respiratory substrate such as succinate is required. However, earlier studies indicated the possible induction of the mitochondrial PT by Ca2+ in the absence of a respiratory substrate (Hunter, D.R., and Haworth, R.A. (1979) Arch. Biochem. Biophys. 195, 453–459). In the present study, we obtained clear evidence showing that the mitochondrial PT could be induced by Ca2+ even in the absence of respiratory substrate. We next examined the protein release from mitochondria that accompanied the induction of PT in the absence of a respiratory substrate. Interestingly, distinct from the ordinary mitochondrial PT induced by Ca2+ in the presence of a respiratory substrate, which is associated with the release of mitochondrial cytochome c and adenylate kinase, the mitochondrial PT occurring in the absence of a respiratory substrate was associated with release of mitochondrial adenylate kinase but not with that of mitochondrial cytochrome c. This experimental system should be quite useful for understanding the mechanisms of protein release from mitochondria. 相似文献
8.
Sea urchin sperm have a single mitochondrion which, aside from its main ATP generating function, may regulate motility, intracellular Ca2+ concentration ([Ca2+]i) and possibly the acrosome reaction (AR). We have found that acute application of agents that inhibit mitochondrial function via differing mechanisms (CCCP, a proton gradient uncoupler, antimycin, a respiratory chain inhibitor, oligomycin, a mitochondrial ATPase inhibitor and CGP37157, a Na+/Ca2+ exchange inhibitor) increases [Ca2+]i with at least two differing profiles. These increases depend on the presence of extracellular Ca2+, which indicates they involve Ca2+ uptake and not only mitochondrial Ca2+ release. The plasma membrane permeation pathways activated by the mitochondrial inhibitors are permeable to Mn2+. Store-operated Ca2+ channel (SOC) blockers (Ni2+, SKF96365 and Gd2+) and internal-store ATPase inhibitors (thapsigargin and bisphenol) antagonize Ca2+ influx induced by the mitochondrial inhibitors. The results indicate that the functional status of the sea urchin sperm mitochondrion regulates Ca2+ entry through SOCs. As neither CCCP nor dicycloexyl carbodiimide (DCCD), another mitochondrial ATPase inhibitor, eliminate the oligomycin induced increase in [Ca2+]i, apparently oligomycin also has an extra mitochondrial target. 相似文献
9.
Previous studies in chick embryo cardiac myocytes have shown that the inhibition of Na+/K+-ATPase with ouabain induces cell shrinkage in an isosmotic environment (290 mOsm). The same inhibition produces an enhanced RVD (regulatory volume decrease) in hyposmotic conditions (100 mOsm). It is also known that submitting chick embryo cardiomyocytes to a hyperosmotic solution induces shrinkage and a concurrent intracellular alkalization. The objective of this study was to evaluate the involvement of intracellular pH (pHi), intracellular Ca2+ ([Ca2+]i) and Na+/K+-ATPase inhibition during hyposmotic swelling. Changes in intracellular pH and Ca2+ were monitored using BCECF and fura-2, respectively. The addition of ouabain (100 M) under both isosmotic and hyposmotic stimuli resulted in a large increase in [Ca2+]i (200%). A decrease in pHi (from 7.3 ± 0.09 to 6.4 ± 0.08, n = 6; p < 0.05) was only observed when ouabain was applied during hyposmotic swelling. This acidification was prevented by the removal of extracellular Ca2+. Inhibition of Na+/H2+ exchange with amiloride (1 mM) had no effect on the ouabain-induced acidification. Preventing the mitochondrial accumulation of Ca2+ using CCCP (10 M) resulted in a blockade of the progressive acidification normally induced by ouabain. The inhibition of mitochondrial membrane K+/H+ exchange with DCCD (1 mM) also completely prevented the acidification. Our results suggest that intracellular acidification upon cell swelling is mediated by an initial Ca2+ influx via Na+/Ca2+ exchange, which under hyposmotic conditions activates the K+ and Ca2+ mitochondrial exchange systems (K+/H+ and Ca2+/H+).Deceased 相似文献
10.
Inhibition of the mitochondrial KATP (mitoKATP) channel abrogates the beneficial effects of preconditioning induced by a brief episode of sublethal ischemia. We studied
the effect of 5-hydroxydecanoate, a well-known inhibitor of the mitoKATP channel, on swelling of isolated liver and brain mitochondria. Volume changes were determined by measurement of light absorbance
at 540 nm. Mitochondrial swelling induced by adding Ca2+ ions correlated with opening of the permeability transition pore as shown by modulation by 1 μM cyclosporin A. In brain mitochondria,
5-hydroxydecanoate did not significantly affect Ca2+-induced swelling. In contrast, 50 or 500 μM 5-hydroxydecanoate increased swelling of liver mitochondria by 9.7 ± 5.1% (n = 6, P = 0.057) and 29.4 ± 1.4% (n = 5, P < 0.0001), respectively. The effect of 5-hydroxydecanoate was blocked by cyclosporin A and was dependent on the presence
of potassium in the medium. In medium containing 200 μM ATP to inhibit the mitoKATP channel, 5–hydroxydecanoate did not further increase Ca2+-induced swelling. We conclude that inhibition of the mitoKATP channel exerts its detrimental effect by facilitation of permeability transition pore opening. 相似文献
11.
Ádám Fekete Laura Franklin Takeshi Ikemoto Balázs Rózsa Balázs Lendvai E. Sylvester Vizi Tibor Zelles 《Journal of neurochemistry》2009,111(3):745-756
Although the role of Na+ in several aspects of Ca2+ regulation has already been shown, the exact mechanism of intracellular Ca2+ concentration ([Ca2+]i) increase resulting from an enhancement in the persistent, non‐inactivating Na+ current (INa,P), a decisive factor in certain forms of epilepsy, has yet to be resolved. Persistent Na+ current, evoked by veratridine, induced bursts of action potentials and sustained membrane depolarization with monophasic intracellular Na+ concentration ([Na+]i) and biphasic [Ca2+]i increase in CA1 pyramidal cells in acute hippocampal slices. The Ca2+ response was tetrodotoxin‐ and extracellular Ca2+‐dependent and ionotropic glutamate receptor‐independent. The first phase of [Ca2+]i rise was the net result of Ca2+ influx through voltage‐gated Ca2+ channels and mitochondrial Ca2+ sequestration. The robust second phase in addition involved reverse operation of the Na+–Ca2+ exchanger and mitochondrial Ca2+ release. We excluded contribution of the endoplasmic reticulum. These results demonstrate a complex interaction between persistent, non‐inactivating Na+ current and [Ca2+]i regulation in CA1 pyramidal cells. The described cellular mechanisms are most likely part of the pathomechanism of certain forms of epilepsy that are associated with INa,P. Describing the magnitude, temporal pattern and sources of Ca2+ increase induced by INa,P may provide novel targets for antiepileptic drug therapy. 相似文献
12.
Judy L. Aschner Hazel Lum Paul W. Fletcher Asrar B. Malik 《Journal of cellular physiology》1997,173(3):387-396
We determined whether activation of phosphatidylinositol-specific phospholipase C (PI-PLC) and a subsequent increase in cytosolic calcium concentration ([Ca2+]i) was an obligatory signaling event mediating the increase in transendothelial permeability induced by bradykinin (BK) and α-thrombin (α-T). Both BK and α-T (each at a concentration range of 0.01–1 μM) caused dose-dependent increases in transendothelial 125I-albumin permeability in cultured bovine pulmonary artery endothelial cell monolayers. Both agonists also produced a rise in inositol (1,4,5)-trisphosphate [Ins(1,4,5)P3] by 10 sec that was followed by a prolonged increase in [Ca2+]i. Pretreatment of endothelial cells with the PLC inhibitor, 1-(6-((17β-3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dion [(U73122) at 10 μM for 15 min], prevented the increases in Ins(1,4,5)P3 and [Ca2+]i induced by both BK and α-T. However, inhibition of PLC with U73122 or another PLC inhibitor, neomycin, did not prevent the increase in endothelial permeability induced by either agonist. In contrast, depletion of cellular protein kinase C (PKC) with phorbol-12-myristate 13-acetate (0.01 μM for 20 hr) increased both BK- and α-T-induced phosphoinositide turnover but inhibited the agonist-induced increase in permeability. A PKC inhibitor, staurosporine (5 μM) likewise inhibited the BK-induced increase in endothelial cell permeability to albumin. We conclude that increases in endothelial permeability induced by the inflammatory mediators, BK and thrombin, can occur independently of PLC activation and increased [Ca2+]i but that a PKC-dependent pathway is required for the permeability response. J. Cell. Physiol. 173:387–396, 1997. © 1997 Wiley-Liss, Inc. 相似文献
13.
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
14.
《生物化学与生物物理学报:疾病的分子基础》1999,1453(1):49-62
The mitochondrial transition pore (MTP) is implicated as a mediator of cell injury and death in many situations. The MTP opens in response to stimuli including reactive oxygen species and inhibition of the electron transport chain. Sporadic Parkinson’s disease (PD) is characterized by oxidative stress and specifically involves a defect in complex I of the electron transport chain. To explore the possible involvement of the MTP in PD models, we tested the effects of the complex I inhibitor and apoptosis-inducing toxin N-methyl-4-phenylpyridinium (MPP+) on cyclosporin A (CsA)-sensitive mitochondrial swelling and release of cytochrome c. In the presence of Ca2+ and Pi, MPP+ induced a permeability transition in both liver and brain mitochondria. MPP+ also caused release of cytochrome c from liver mitochondria. Rotenone, a classic non-competitive complex I inhibitor, completely inhibited MPP+-induced swelling and release of cytochrome c. The MPP+-induced permeability transition was synergistic with nitric oxide and the adenine nucleotide translocator inhibitor atractyloside, and additive with phenyl arsine oxide cross-linking of dithiol residues. MPP+-induced pore opening and cytochrome c release were blocked by CsA, the Ca2+ uniporter inhibitor ruthenium red, the hydrophobic disulfide reagent N-ethylmaleimide, butacaine, and the free radical scavenging enzymes catalase and superoxide dismutase. MPP+ neurotoxicity may derive from not only its inhibition of complex I and consequent ATP depletion, but also from its ability to open the MTP and to release mitochondrial factors including Ca2+ and cytochrome c known to be involved in apoptosis. 相似文献
15.
Intracellular Ca2+ ([Ca2+]i) dynamics were studied in identified rat gonadotropes using the whole-cell patch-clamp technique in conjunction with Indo-1 photometry. The kinetics of depolarization-induced [Ca2+]i transients vary with Ca2+ load. In addition to a rapid initial decay, large (> 500 nM) [Ca2+]i transients have a slow plateau phase. Application of the mitochondrial inhibitor carbonyl cyanide m-chlorophenylhydrazone (CCCP) significantly slows the decay of [Ca2+]i transients, consistent with stopping uptake of Ca2+ by mitochondria. CCCP causes a small increase of [Ca2+]i at rest. After a large Ca2+ entry the amount is much larger, consistent with release from a mitochondrial Ca2+ pool that fills during cytoplasmic Ca2+ loading. The rate of Ca2+ uptake by mitochondria is dependent upon [Ca 2+]i. Consistent with previous studies, gonadotropin releasing hormone (GnRH) induces [Ca2+]i oscillations. The mitochondrial inhibitors CCCP and cyanide (CN−) terminate these oscillations. The mitochondrial ATP-synthase inhibitor oligomycin reduces the frequency and increases the amplitude of the oscillations. In the presence of ruthenium red (a non-specific blocker of the mitochondrial Ca2+-uniporter) in the pipette, GnRH does not induce rhythmic [Ca2+]i oscillations. We suggest that mitochondria play a significant role in the rapid clearance of cytosolic Ca2+ loads in gonadotropes and participate in GnRH-induced periodic [Ca2+]i oscillations. 相似文献
16.
The mitochondrial membrane permeability transition induced byCa2+ is inhibited by quinine in a dose-dependent fashion.Competition experiments strongly suggest that quinine displacesCa2+ bound to the inner membrane. This is supported byexperiments showing that quinine inhibits Ca2+-dependent butnot Ca2+-independent mitochondrial swelling induced byphenylarsine oxide. As with Ca2+ chelators, quinine inducespermeability transition pore closure preventing the contraction induced bypoly(ethylene glycol) 2000 in mitochondria preswollen by incubation in KSCNmedium containing Ca2+ and inorganic phosphate. These resultssuggest that quinine dislodges Ca2+ bound to the protein site,which triggers pore opening. 相似文献
17.
Oxidative stress and reactive oxygen species (ROS) generation can be influenced by G-protein coupled receptor (GPCR)-mediated regulation of intracellular Ca2+ ([Ca2+]i) signaling. ROS production are much higher in proximal tubular (PT) cells; in addition, the lack of antioxidants enhances the vulnerability to oxidative damage. Despite such predispositions, PT cells show resiliency, and therefore must possess some inherent mechanism to protect from oxidative damage. While the mechanism in unknown, we tested the effect of l-ornithine, since it is abundantly present in PT luminal fluid and can activate Ca2+-sensing receptor (CaSR), a GPCR, expressed in the PT luminal membrane. We used human kidney 2 (HK2) cells, a PT cell line, and performed Ca2+ imaging and electrophysiological experiments to show that l-ornithine has a concentration-dependent effect on CaSR activation. We further demonstrate that the operation of CaSR activated Ca2+ signaling in HK-2 cells mediated by the transient receptor potential canonical (TRPC) dependent receptor-operated Ca2+ entry (ROCE) using pharmacological and siRNA inhibitors. Since PT cells are vulnerable to ROS, we simulated such deleterious effects using genetically encoded peroxide-induced ROS production (HyperRed indicator) to show that the l-ornithine-induced ROCE mediated [Ca2+]i signaling protects from ROS production. Furthermore, we performed cell viability, necrosis and apoptosis assays, and mitochondrial oxidative gene expression to establish that presence of l-ornithine rescued the ROS-induced damage in HK-2 cells. Moreover, l-ornithine-activation of CaSR can reverse ROS production and apoptosis via mitogen-activated protein kinase p38 activation. Such nephroprotective role of l-ornithine can be useful as the translational option for reversing kidney diseases involving PT cell damage due to oxidative stress or crystal nephropathies. 相似文献
18.
Tat’yana Trendeleva Evgeniya Sukhanova Ludmila Ural’skaya Nils-Erik Saris Renata Zvyagilskaya 《Journal of bioenergetics and biomembranes》2011,43(6):623-631
In this study we used tightly-coupled mitochondria from Yarrowia lipolytica and Dipodascus (Endomyces) magnusii yeasts. The two yeast strains are good alternatives to Saccharomyces cerevisiae, being aerobes containing well-structured mitochondria (thus ensuring less structural limitation to observe their appreciable
swelling) and fully competent respiratory chain with three invariantly functioning energy conservation points, including Complex
I, that can be involved in induction of the canonical Ca2+/Pi-dependent mitochondrial permeability transition (mPTP pore) with an increased open probability when electron flux increases
(Fontaine et al. J Biol Chem 273:25734–25740, 1998; Bernardi et al. FEBS J 273:2077–2099, 2006). High-amplitude swelling and collapse of the membrane potential were used as parameters for demonstrating pore opening.
Previously (Kovaleva et al. J Bioenerg Biomembr 41:239–249, 2009; Kovaleva et al. Biochemistry (Moscow) 75:297–303, 2010) we have shown that mitochondria from Y. lipolytica and D. magnusii were very resistant to the Ca2+ overload combined with varying concentrations of Pi, palmitic acid, SH-reagents, carboxyatractyloside (an inhibitor of ADP/ATP translocator), as well as depletion of intramitochondrial
adenine nucleotide pools, deenergization of mitochondria, and shifting to acidic pH values in the presence of high [Pi]. Here we subjected yeast mitochondria to other conditions known to induce an mPTP in animal and plant mitochondria, namely
to Ca2+ overload under hypoxic conditions (anaerobiosis). We were unable to observe Ca2+-induced high permeability of the inner membrane of D. magnusii and Y. lipolytica yeast mitochondria under anaerobic conditions, thus suggesting that an mPTP-like pore, if it ever occurs in yeast mitochondria,
is not coupled with the Ca2+ uptake. The results provide the first demonstration of ATP-dependent energization of yeast mitochondria under conditions
of anaerobiosis. 相似文献
19.
Zhenghang Zhao Richard Gordan Hairuo Wen Nadezhda Fefelova Wei-Jin Zang Lai-Hua Xie 《PloS one》2013,8(11)
Recent studies have suggested that mitochondria may play important roles in the Ca2+ homeostasis of cardiac myocytes. However, it is still unclear if mitochondrial Ca2+ flux can regulate the generation of Ca2+ waves (CaWs) and triggered activities in cardiac myocytes. In the present study, intracellular/cytosolic Ca2+ (Cai
2+) was imaged in Fluo-4-AM loaded mouse ventricular myocytes. Spontaneous sarcoplasmic reticulum (SR) Ca2+ release and CaWs were induced in the presence of high (4 mM) external Ca2+ (Cao
2+). The protonophore carbonyl cyanide p-(trifluoromethoxy)phenylhydrazone (FCCP) reversibly raised basal Cai
2+ levels even after depletion of SR Ca2+ in the absence of Cao
2+ , suggesting Ca2+ release from mitochondria. FCCP at 0.01 - 0.1 µM partially depolarized the mitochondrial membrane potential (Δψ
m) and increased the frequency and amplitude of CaWs in a dose-dependent manner. Simultaneous recording of cell membrane potentials showed the augmentation of delayed afterdepolarization amplitudes and frequencies, and induction of triggered action potentials. The effect of FCCP on CaWs was mimicked by antimycin A (an electron transport chain inhibitor disrupting Δψ
m) or Ru360 (a mitochondrial Ca2+ uniporter inhibitor), but not by oligomycin (an ATP synthase inhibitor) or iodoacetic acid (a glycolytic inhibitor), excluding the contribution of intracellular ATP levels. The effects of FCCP on CaWs were counteracted by the mitochondrial permeability transition pore blocker cyclosporine A, or the mitochondrial Ca2+ uniporter activator kaempferol. Our results suggest that mitochondrial Ca2+ release and uptake exquisitely control the local Ca2+ level in the micro-domain near SR ryanodine receptors and play an important role in regulation of intracellular CaWs and arrhythmogenesis. 相似文献
20.
Eneida J. Da Lozzo Maria Benigna M. Oliveira Eva Gunilla S. Carnieri 《Journal of biochemical and molecular toxicology》1998,12(5):291-297
The effects of mycotoxin citrinin on Ca2+ efflux and membrane permeabilization were studied in isolated rat liver mitochondria. The efflux rate observed when in presence of ruthenium red was higher when citrinin was added. Swelling experiments demonstrated Ca2+-dependent membrane permeabilization by citrinin. Catalase, butylhydroxitoluene (BHT), and dithiothreitol (DTT) did not protect swelling caused by Ca2+ plus citrinin. The protection conferred by ATP–Mg2+ and cyclosporin A in the latter experiments are strong indications of pore formation. These results suggest that citrinin can induce permeability transition by a mechanism that does not involve oxidative damage. © 1998 John Wiley & Sons, Inc. J Biochem Toxicol 12: 291–297, 1998 相似文献