共查询到20条相似文献,搜索用时 31 毫秒
1.
Marianne S. Jurkowitz Gerald P. Brierley 《Journal of bioenergetics and biomembranes》1982,14(5-6):435-449
A rapid loss of accumulated Ca2+ is produced by addition of H+ to isolated heart mitochondria. The H+-dependent Ca+ efflux requires that either (a) the NAD(P)H pool of the mitochondrion be oxidized, or (b) the endogenous adenine nucleotides be depleted. The loss of Ca2+ is accompanied by swelling and loss of endogenous Mg2–. The rate of H+-dependent Ca2+ efflux depends on the amount of Ca2+ and Pi taken up and the extent of the pH drop imposed. In the absence of ruthenium red the H+-induced Ca2+-efflux is partially offset by a spontaneous re-accumulation of released Ca2+. The H+-induced Ca2+ efflux is inhibited when the Pi transporter is blocked withN-ethylmaleimide, is strongly opposed by oligomycin and exogenous adenine nucleotides (particularly ADP), and inhibited by nupercaine. The H+-dependent Ca2+ efflux is decreased markedly when Na+ replaces the K+ of the suspending medium or when the exogenous K+/H+ exchanger nigericin is present. These results suggest that the H+-dependent loss of accumulated Ca2+ results from relatively nonspecific changes in membrane permeability and is not a reflection of a Ca2+/H+ exchange reaction. 相似文献
2.
- 1. 1. It has previously been demonstrated that an increase in extracellular Ca2+ concentration induces a transient increase in K+ permeability and associated hyperpolarization of the red cell membrane of the giant salamander, Amphiuma means. This phenomenon is analogous to the Ca2+-induced KCl loss observed in ATP-depleted human red cells and red cell ghosts.
- 2. 2. Histamine, which enhances the Ca2+-induced K+ loss from depleted human red cells, is without effect on this Ca2+-induced hyperpolarization of Amphiuma red cells.
- 3. 3. Promethazine (10 μM) and mepyramine (1 mM), which inhibit the Ca2+-induced K+ loss in depleted human red cells, also block the Ca2+-related hyperpolarization of Amphiuma erythrocytes.
- 4. 4. Chlorpromazine (25 μM), despite being a weak antihistamine, is equally effective in blocking the Ca2+-induced hyperpolarization of Amphiuma red cells.
- 5. 5. Ionophore A23187 causes a large and sustained Ca2+/K+-dependent hyperpolarization even in the presence of normal (1.8 mM) concentrations of Ca2+. This hyperpolarization is relatively insensitive to chlorpromazine and promethazine.
- 6. 6. The inhibition of the Ca2+-induced hyperpolarization of the Amphiuma red cell membrane by chlorpromazine and promethazine may be related to their properties as local anaesthetics.
Abbreviations: MOPS, morpholinopropane sulphonate 相似文献
3.
Bongkrekic acid and atractyloside, inhibitors of adenine nucleotide translocase, do not inhibit Ca2+ uptake and H+ production by pig heart mitochondria. However, bongkrekic acid, but not atractyloside, inhibits dinitrophenol-induced Ca2+ efflux and H+ uptake. Conversely, ruthenium red blocks Ca2+ uptake and H+ production but does not prevent dinitrophenol-induced Ca2+ efflux and H+ uptake by mitochondria. These results suggest that mitochondrial Ca2+ uptake and release exist as two independent pathways. The efflux of Ca2+ from mitochondria is mediated by a bongkrekic acid sensitive component which is apparently not identical to the ruthenium red sensitive Ca2+ uptake carrier. 相似文献
4.
《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
5.
Leon Pape 《生物化学与生物物理学报:生物膜》1982,686(2):225-232
Changes in fluorescence intensity of thiodicarbocyanine, DiS-C3(5), were correlated with direct microelectrode potential measurements in red blood cells from Amphiuma means and applied qualitatively to evaluate the effects of extracellular Ca2+, K+ and pH on the membrane potential of human red cells. Increasing extracellular [Ca2+] from 1.8 to 15 mM causes a K+-dependent hyperpolarization and decrease in fluorescence intensity in Amphiuma red cells. Both the hyperpolarization and fluorescence change disappear when the temperature is raised from 17 to 37°C. No change in fluorescence intensity is observed in human red cells with comparable increase in extracellular Ca2+ in the temperature range 5–37°C. Increasing the extracellular pH, however, causes human red cells to respond to an increase in extracellular Ca2+ with a significant but temporary loss in fluorescence intensity. This effect is blocked by EGTA, quinine or by increasing extracellular [K+], indicating that at elevated extracellular pH, human erythrocytes respond to an increase in extracellular Ca2+ with an opening of K+ channels and associated hyperpolarization of the plasma membrane. 相似文献
6.
When red cells are starved or incubated in the presence of metabolic poisons, with or without substrates, a large increase in K+ permeability is observed which depends on the presence of Ca2+ in the medium. The production or removal of a metabolite which controls the K+ permeability has been proposed to explain these effects. In the present experiments, a parallelism is found to exist between the rate of ATP depletion and the increase in Ca2+ uptake and K+ loss when red cells are depleted by different methods. The results support the view that the intracellular concentration of ATP may be the main factor on which the rate of Ca2+ uptake and the subsequent increase in K+ permeability depend. 相似文献
7.
Bulk water transport in reconstituted ghosts is statistically comparable to that in the parent red cells, and is unaffected by incorporation of Ca2+ over the range of 0.01 to 1 mM. Brief exposure of ghosts to p-chloromercuribenzene sulfonate results in a supression of osmotic water flow but leaves K+ permeability unchanged. Incorporation of p-chloromercuribenzene sulfonate provokes extremely rapid K+ loss which can be counteracted by simultaneous inclusion of Ca2+.Erythrocyte ghosts, when prepared with a small amount of Ca2+, demonstrate recovery of normal impermeability to choline, sucrose, Na+ and inulin and have an improved K+ retention over Ca2+-free preparations.The rate of passive transport of K+ from unwashed erythrocyte ghosts was measured during the initial few minutes of efflux. The initial rates vary in a bimodal fashion with the concentration of Ca2+ incorporated at the time of hemolysis. In low concentrations (0.01–0.1 mM), Ca2+ protects the K+ barrier while at higher concentrations (0.1–1.0 mM) it provokes a K+ leakage ranging from 7 to 50 times the normal rate of passive K+ loss. The Ca2+-induced K+ leak is thus a graded response rather than a discrete membrane transport state. The transition from a Ca2+-protected to a Ca2+-damaged membrane occurs upon an increase in Ca2+ concentration of less than 50 μmoles/l. 相似文献
8.
Abstract: Morphine-induced release of adenosine from the spinal cord is believed to contribute to spinal antinociception. Although this release is Ca2+ dependent, little is known of the nature of this dependence. In this study, the effects of the dihydropyridine L-type Ca2+ channel agonist Bay K 8644 and the antagonist nifedipine, the N-type Ca2+ channel antagonist ω-conotoxin, and ruthenium red, a blocker of Ca2+ influx induced by capsaicin, on release of adenosine evoked by morphine were determined. The effect of partial depolarization with a minimally effective concentration of K+ on morphine-evoked release of adenosine also was examined. Morphine 10?5-10?4M produced a dose-dependent enhancement of adenosine release from dorsal spinal cord synaptosomes. Following the addition of 6 mM K+ (total K+ concentration of 10.7 mM), 10?6M morphine also enhanced release, and an additional component of action at 10?8M was revealed. Release was Ca2+-dependent as it was not observed in the absence of Ca2+ and presence of EGTA. Bay K 8644 (10 nM) and nifedipine (100 nM) had no effect on the release of adenosine evoked by morphine, but ω-conotoxin (100 nM) markedly reduced such release in both the absence and the presence of the additional 6 mM K+. Morphine-evoked adenosine release was not altered in the presence of a partially effective dose of capsaicin, nor by ruthenium red. These results indicate that morphine can stimulate two distinct phases of adenosine release from the spinal cord (nanomolar and micromolar), and that both phases of release are due to Ca2+ entry via ω-conotoxin-sensitive N-type Ca2+ channels. 相似文献
9.
E. I. Khoroshavina M. V. Dubinin A. V. Khokhlov V. N. Samartsev 《Biochemistry (Moscow) Supplemental Series A: Membrane and Cell Biology》2018,12(2):128-136
The effect of bile acids as inducers of Ca2+ efflux from the matrix was studied on isolated rat liver mitochondria. Mitochondria in the presence of cyclosporin A (CsA) were energized by succinate, then loaded with Ca2+ and after the addition of the calcium uniporter inhibitor ruthenium red were de-energized by malonate. It was shown that under these conditions hydrophobic bile acids lithocholic and chenodeoxycholic at concentrations of 10 and 30 μM respectively and hydrophilic bile acids ursodeoxycholic and cholic at a concentration of 400 μM induce Ca2+ efflux from the mitochondrial matrix. It is noted that the efflux of these ions is not associated with damage of the inner mitochondrial membrane by bile acids, since it is accompanied by the generation of Δψ, i.e., the formation of the diffusion potential. It is assumed that along with induction of calcium efflux from the matrix, bile acids are also capable of transporting hydrogen and potassium ions in the opposite direction, i.e., perform H+/Ca2+ and K+/Ca2+ exchange. It was found that ruthenium red added to Ca2+-loaded energized mitochondria prevents the return of these ions to the matrix and weakens the effect of chenodeoxycholic acid as an inducer of the CsA-sensitive mitochondrial pore and the effect of ursodeoxycholic acid as an inducer of CsA-insensitive permeability of the inner mitochondrial membrane. We conclude that in the conditions of the calcium uniporter activity decrease, Ca2+ efflux from the matrix induced by bile acids can be considered as one of the mechanisms reducing their effectiveness as inducers of the Ca2+-dependent CsA-sensitive pore and CsA-insensitive permeability transition in mitochondria. 相似文献
10.
Ming-Feng Tsai Dawei Jiang Linlin Zhao David Clapham Christopher Miller 《The Journal of general physiology》2014,143(1):67-73
The leucine zipper, EF hand–containing transmembrane protein 1 (Letm1) gene encodes a mitochondrial inner membrane protein, whose depletion severely perturbs mitochondrial Ca2+ and K+ homeostasis. Here we expressed, purified, and reconstituted human Letm1 protein in liposomes. Using Ca2+ fluorophore and 45Ca2+-based assays, we demonstrate directly that Letm1 is a Ca2+ transporter, with apparent affinities of cations in the sequence of Ca2+ ≈ Mn2+ > Gd3+ ≈ La3+ > Sr2+ >> Ba2+, Mg2+, K+, Na+. Kinetic analysis yields a Letm1 turnover rate of 2 Ca2+/s and a Km of ∼25 µM. Further experiments show that Letm1 mediates electroneutral 1 Ca2+/2 H+ antiport. Letm1 is insensitive to ruthenium red, an inhibitor of the mitochondrial calcium uniporter, and CGP-37157, an inhibitor of the mitochondrial Na+/Ca2+ exchanger. Functional properties of Letm1 described here are remarkably similar to those of the H+-dependent Ca2+ transport mechanism identified in intact mitochondria. 相似文献
11.
Gerald P. Brierley Kemal Baysal Dennis W. Jung 《Journal of bioenergetics and biomembranes》1994,26(5):519-526
It is now well established that mitochondria contain three antiporters that transport monovalent cations. A latent, allosterically regulated K+/H+ antiport appears to serve as a cation-extruding device that helps maintain mitochondrial volume homeostasis. An apparently unregulated Na+/H+ antiport keeps matrix [Na+] low and the Na+-gradient equal to the H+-gradient. A Na+/Ca2+ antiport provides a Ca2+-extruding mechanism that permits the mitochondrion to regulate matrix [Ca2+] by balancing Ca2+ efflux against influx on the Ca2+-uniport. All three antiports have well-defined physiological roles and their molecular properties and regulatory features are now being determined. Mitochondria also contain monovalent cation uniports, such as the recently described ATP- and glibenclamide-sensitive K+ channel and ruthenium red-sensitive uniports for Na+ and K+. A physiological role of such uniports has not been established and their properties are just beginning to be defined. 相似文献
12.
Calcium uptake of cardiac muscle and fast-twitch and slow-twitch skeletal muscle of rabbit was measured in 10-μm thin sections. Ca2+ uptake showed K+, Mg2+, Ca2+, and oxalate dependence and required ATP. The contribution of mitochondria to the Ca2+ uptake could be ruled out, since inclusion of ruthenium red or sodium azide in the medium did not show inhibition. The method, which avoids unphysiological fragmentation of the sarcoplasmic reticulum, has the added advantage of requiring only 0.1 to 0.3 g of muscle and permitting simultaneous histochemical studies from the same muscle block. 相似文献
13.
Isolated, intact rat liver mitochondria, without extraneous substrates but loaded with Ca2+ (20 nmol/mg), can be observed to release Ca2+ when treated with ruthenium red. Such release can be inhibited by 0.33 mM dlisocitrate but not by 10 mM dl-β-hydroxybutyrate. Assays of NADP+, NADPH, NAD+, and NADH revealed that only the reduction of NADP+ can be linked with such inhibition of Ca2+ release, not that of NAD+. Since ruthenium redinsensitive Ca2+ release is a physiological (but normally masked) process, this experimental approach avoids some potential problems ascribed to strong pyridine nucleotide oxidation. It is suggested that specific NADP+:NADPH dependent reactions are part of a physiological mechanism regulating Ca2+ release/retention. 相似文献
14.
- 1.
- 1. The hypothesis that the inhibitory action of ouabain on the Ca2+-dependent increase in K+ permeability observed in depleted human red cells is mediated by changes in the intracellular level of ATP was tested by measuring simultaneously the ouabain sensitive K+ loss and the concentration of ATP in depleted guinea-pig red cells in the presence and absence of external Ca2+. 相似文献
15.
Ruthenium red, a powerful inhibitor of Ca2+ transport by mitochondria, does not inhibit the active Ca2+ uptake by sarcoplasmic reticulum isolated from rabbit skeletal muscle promoted by 5 mM ATP-Mg in the presence or absence of potassium oxalate. Although concentrations of ruthenium red up to 100 μM do not affect the active uptake of Ca2+, 25 μM of the inorganic dye inhibit the passive binding of Ca2+ by about 50%. This inhibitory effect is observed in sarcoplasmic reticulum even after its lipid fraction is extracted with acetone.Although active Ca2+ uptake by sarcoplasmic reticulum is not inhibited by ruthenium red, in the absence of oxalate it inhibits significantly the Ca2+-dependent ATPase activity but not the Mg2+-ATPase. However, if potassium oxalate is present, the Ca2+-stimulated ATPase is not sensitive to the dye. It is not clear how oxalate functions to protect the Ca2+-ATPase against the inhibitor effect of ruthenium red.The high sensitivity to ruthenium red of the Ca2+ transport mechanism in mitochondria as compared to the Ca2+ transport in sarcoplasmic reticulum may be useful in determining the extent to which each organelle functions in the cell to regulate intracellular free Ca2+. 相似文献
16.
At 0°C, where Ca2+ efflux is not observed, the uptake of Ca2+ by Ehrlich ascites tumor cells consists of four components: 1) An energy-dependent mitochondrial component, which is inhibited by uncouplers, respiratory inhibitors, and mitochondrial ATP-ase inhibitors. 2) Binding to the cell surface, which can be displaced by an EGTA wash. 3) An electrochemical gradient-dependent component, which is inhibited by agents which dissipate these gradients, such as proton ionophores, metabolic uncouplers, and valinomycin. The valinomycin inhibition of this transport component is dependent on K+ concentration. 4) Passive diffusion, which is dependent on Ca2+ concentration and is observed in the presence of inhibitors of the other components. The uptake of Ca2+ at 0°C is sensitive to ruthenium red presumably due to its competition with Ca2+ for cell binding sites. 相似文献
17.
Summary (i) In human red cell membranes the sensitivity to N-ethylmaleimide of Ca2+-dependent ATPase and phosphatase activities is at least ten times larger than the sensitivity to N-ethylmaleimide of (Na++K+)-ATPase and K+-activated phosphatase activities. All activities are partially protected against N-ethylmaleimide by ATP but not by inorganic phosphate or byp-nitrophenylphosphate. (ii) Protection by ATP of (Na++K+)-ATPase is impeded by either Na+ or K+ whereas only K+ impedes protection by ATP of K+-activated phosphatase. On the other hand, Na+ or K+ slightly protects Ca2+-dependent activities against N-ethylmaleimide, this effect being independent of ATP. (iii) The sensitivity to N-ethylmaleimide of Ca2+-dependent ATPase and phosphatase activities is markedly enhanced by low concentrations of Ca2+. This effect is half-maximal at less than 1 m Ca2+ and does not require ATP, which suggests that sites with high affinity for Ca2+ exist in the Ca2+-ATPase in the absence of ATP. (iv) Under all conditions tested the response to N-ethylmaleimide of the ATPase and phosphatase activites stimulated by K+ or Na+ in the presence of Ca2+ parallels that of the Ca2+-dependent activities, suggesting that the Ca2+-ATPase system possesses sites at which monovalent cations bind to increase its activity. 相似文献
18.
Coated microvesicle fractions isolated from ox forebrain cortex by the ultracentrifugation procedure of Pearse (1) and by the modified, less time consuming method of Keen et al (2) had comparable Ca2++Mg2+ dependent ATPase activities (about 9 μmol/h per mg protein). The Na++K++Mg2+ dependent ATPase activity was 3.2 μmol/h per mg (±1.0, S.D., n=3) when microvesicles were prepared according to (1) and 1.5 μmol/h per mg (±1.0, S.D., n=3) when prepared according to (2).Oligomycin, ruthenium red, and trifluoperazine, inhibitors of Ca2+ transport in mitochondria and erythrocyte membranes had no effect on Ca2++Mg2+ dependent ATPase from any of the preparations.As demonstrated both by ATPase assays and electron microscopy, coated microvesicles could be bound to immunosorbents prepared with poly-specific antibodies against a coated microvesicle fraction obtained by the method of Pearse (1). The binding could be inhibited by dissolved coat protein using partially purified clathrin. The fraction of coated vesicles eluted from the immunosorbent was purified relative to the starting material as judged by electron microscopy.The Ca2++Mg2+ ATPase activity and calmodulin content was copurified with the coated microvesicles and the specific activity of Na++K++Mg2+ ATPase was decreased.Na++K++Mg2+ dependent ATPase activity in the coated microvesicle fraction could be ascribed to membranes with the appearance of microsomes. These membranes were also bound to the immunosorbents, but the binding was not influenced by clathrin. The capacity of the immunosorbents for these membranes was less than for the coated microvesicles, resulting in a decrease of Na++K++Mg2+ dependent ATPase activity in the eluted coated microvescile fraction.It was concluded that Ca2++Mg2+ ATPase activity is not a contamination from plasma membrane vesicles or mitochondrial membranes but seems to be an integral part of the coated vesicle membrane. 相似文献
19.
Summary Passive Ca2+ influx is gradually enhanced by 0.5 to 5mm propranolol in fresh and phosphate ester-depleted human red cells. In fresh cells the active Ca2+ efflux tends to counteract Ca2+ uptake. Membrane hyperpolarization, induced by the K+ transport that accompanies Ca2+ uptake, further enhances the rate of Ca2 uptake. The dissociated, positively charged form of propranolol seems to be crucial in the increase of passive Ca2+ influx caused by the drug. The effect can be attributed to the release of structural Ca2+ from the membrane (lipids).The release of structural Ca2+ promotes the formation of the selectively K+-permeable membrane structure as well. The transitions of lipid structure responsible for the opening of the passive Ca2+ and K+ pathways, however, are not identical. The opening of the K+ pathways is prevented by certain highly lipid-soluble substances (chlorobutanol, heptanol, oligomycin, etc.), whereas the formation of the Ca2+ pathways is unaffected. Passive K+ transport is inhibited by high propranolol concentrations (more intensively at alkaline pH), whereas Ca2+ transport is promoted. A further difference between the passive K+ and Ca2+ pathways is that SH-proteins also seem to be involved in the formation of the K+ pathways, whereas they do not play a specific role in the opening of the passive Ca2+ channels. The additional Ca2+ binding that triggers the formation of the K+ pathways also seems to occur in the protein area of the inner membrane surface. 相似文献
20.
Influence of Tl+ on mitochondrial permeability transition pore in Ca2+-loaded rat liver mitochondria
The Tl+-induced opening of the MPTP in Ca2+-loaded rat liver mitochondria energized by respiration on the substrates succinate or glutamate plus malate was recorded as increased swelling and dissipation of mitochondrial membrane potential as well as decreased state
4, or state 3, or 2,4-dinitrophenol-stimulated respiration. These effects of Tl+ increased in nitrate media containing monovalent cations in the order of Li+ < NH4+ ≤ Na+ < K+. They were potentiated by inorganic phosphate and diminished by the MPTP inhibitors (ADP, CsA, Mg2+, Li+, rotenone, EGTA, and ruthenium red) both individually and more potently in their combinations. Maximal swelling of both non-energized
and energized Ca2+-loaded mitochondria in rotenone-free media is an indication of Ca2+ uptake driven by respiration on mitochondrial endogenous substrates. It is suggested that Tl+ (distinct from Cd2+, Hg2+, and other heavy metals and regardless of the used respiratory substrates) can stimulate opening of the MPTP only in the
presence of Ca2+. We discuss the possible participation of Ca2+-binding sites, located near the respiratory complex I and the adenine nucleotide translocase, in inducing opening of the
MPTP. 相似文献