1
|
Satrústegui J, Pardo B, Del Arco A. Mitochondrial Transporters as Novel Targets for Intracellular Calcium Signaling. Physiol Rev 2007; 87:29-67. [PMID: 17237342 DOI: 10.1152/physrev.00005.2006] [Citation(s) in RCA: 203] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Ca2+signaling in mitochondria is important to tune mitochondrial function to a variety of extracellular stimuli. The main mechanism is Ca2+entry in mitochondria via the Ca2+uniporter followed by Ca2+activation of three dehydrogenases in the mitochondrial matrix. This results in increases in mitochondrial NADH/NAD ratios and ATP levels and increased substrate uptake by mitochondria. We review evidence gathered more than 20 years ago and recent work indicating that substrate uptake, mitochondrial NADH/NAD ratios, and ATP levels may be also activated in response to cytosolic Ca2+signals via a mechanism that does not require the entry of Ca2+in mitochondria, a mechanism depending on the activity of Ca2+-dependent mitochondrial carriers (CaMC). CaMCs fall into two groups, the aspartate-glutamate carriers (AGC) and the ATP-Mg/Picarriers, also named SCaMC (for short CaMC). The two mammalian AGCs, aralar and citrin, are members of the malate-aspartate NADH shuttle, and citrin, the liver AGC, is also a member of the urea cycle. Both types of CaMCs are activated by Ca2+in the intermembrane space and function together with the Ca2+uniporter in decoding the Ca2+signal into a mitochondrial response.
Collapse
Affiliation(s)
- Jorgina Satrústegui
- Departamento de Biología Molecular Centro de Biología Molecular "Severo Ochoa" UAM-CSIC, Facultad de Ciencias, Universidad Autónoma, Madrid, Spain.
| | | | | |
Collapse
|
2
|
de la Cruz MJ, Alemany J, Roncero I, Albert P. Changes induced by caffeine, theophylline and theobromine on calcium uptake, respiration and ATP levels in rat-liver mitochondria. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. C, COMPARATIVE PHARMACOLOGY AND TOXICOLOGY 1988; 91:443-7. [PMID: 2905960 DOI: 10.1016/0742-8413(88)90057-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
1. The inhibition of calcium uptake and cellular respiration depend on the concentration of the compounds as shown by the concentration-effect curves. 2. The concentrations at which 50% inhibition of the transport of calcium takes place (caffeine 45 mM, theophylline 12 mM, theobromine, 4 mM) do not coincide exactly with those that produce the same effect on cellular respiration (caffeine 60 mM, theophylline 22 mM, theobromine 8 mM). 3. ATP concentrations under different conditions were also determined; a decrease in their value induced by the drugs was observed. No significant differences were observed, however, between the effect produced by the methyl-xanthines. 4. These findings suggest that these compounds are able to affect in some way the maintenance of energy gradients linked to the effects studied.
Collapse
Affiliation(s)
- M J de la Cruz
- Departamento de Bioquímica, Facultad de Medicina, Universidad Complutense de Madrid, Spain
| | | | | | | |
Collapse
|
3
|
Selak MA, Scandella CJ. Respiration capacity of mitochondria isolated from unfertilized and fertilized sea urchin eggs. Exp Cell Res 1987; 169:369-78. [PMID: 3556423 DOI: 10.1016/0014-4827(87)90197-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Mitochondria were isolated from unfertilized and fertilized eggs of the sea urchin, Strongylocentrotus purpuratus. Both preparations exhibited coupled adenosine 5'-diphosphate (ADP)-dependent) oxidation of flavin and pyridine-linked substrates and both yielded the expected P:O ratios with these substrates. Highest respiratory control indices (greater than 4.0) were observed when succinate or pyruvate + malate were used as substrates. Mitochondria from unfertilized and fertilized eggs exhibited sensitivity to respiratory and phosphorylation inhibitors and uncouplers and both preparations exhibited cross-over points at sites I, II and III of the respiratory chain. Low-temperature difference spectra revealed a normal complement of cytochromes c, b and aa3, although cytochrome c from unfertilized eggs appears to be more subject to extraction during the course of mitochondrial isolation than does cytochrome c from fertilized eggs. An unidentified pigment absorbing at approx. 570 nm was visible in low-temperature spectra of unfertilized eggs and unfertilized egg mitochondria.
Collapse
|
4
|
Holan G, Smith DRJ. A new selective insecticidal uncoupler of oxidative phosphorylation. Cell Mol Life Sci 1986. [DOI: 10.1007/bf01946702] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
|
5
|
Hansford RG. Relation between mitochondrial calcium transport and control of energy metabolism. Rev Physiol Biochem Pharmacol 1985; 102:1-72. [PMID: 2863864 DOI: 10.1007/bfb0034084] [Citation(s) in RCA: 301] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
|
6
|
Chapter 9 The uptake and the release of calcium by mitochondria. ACTA ACUST UNITED AC 1984. [DOI: 10.1016/s0167-7306(08)60319-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
|
7
|
Kissel VA, Hartig WJ. Characterization of the respiratory activity of mitochondria isolated from an insect cell line CP-1268 Laspeyresia pomonella. IN VITRO 1983; 19:529-37. [PMID: 6307858 DOI: 10.1007/bf02619601] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Mitochondria have been isolated from the codling moth Laspeyresia pomonella, CP-1268 cell line. The mitochondrial fraction was isolated from pooled 4 d, exponential growth phase, cultures. The mitochondria were determined to be intact based on the demonstration of respiratory control, the effects of 2,4 dinitrophenol and oligomycin on respiration, the inability to oxidize NADH, and the inability of cytochrome c to enhance respiration. The isolated mitochondria were able to oxidize succinate, pyruvate, malate, alpha-ketoglutarate, and alpha-glycerophosphate efficiently. Of the substrates tested, the CP-1268 mitochondria oxidized succinate most efficiently. The respiratory control ratios ranged from a high of 4.6 for pyruvate to a low of 1.7 with alpha-glycerophosphate. These findings confirm that the mitochondria were tightly coupled. The data also confirm the presence of three sites of oxidative phosphorylation because NAD-linked substrates had ADP-to-O ratios approaching 3 and flavoprotein linked substrates had values approaching 2.
Collapse
|
8
|
|
9
|
Akberali HB, Earnshaw MJ. The mechanism of calcium transport in mitochondria isolated from the marine mussel, Mytilus edulis (L.). Cell Calcium 1982; 3:55-66. [PMID: 6179627 DOI: 10.1016/0143-4160(82)90037-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Isolated mussel mitochondria produced a less pronounced transient stimulation of respiration upon the addition of Ca2+ in a reaction medium containing Pi and a slower rate of Ca2+ transport compared to rat liver mitochondria. The initial rates of Ca2+ transport in the absence of Pi were more similar and both types of mitochondria possessed a sigmoidal relationship between the initial rate of Ca2+ transport and the free Ca2+ concentration ("Km" approximately 5 microM). Ruthenium red produced an equal maximal inhibition of the initial rate of Ca2+ transport in both types of mitochondria but mussel mitochondria were rather more resistant to the inhibitor. The major difference found was that approximately 15 nmoles La3+ mg protein-1 was required to produce maximal inhibition of the initial rate of Ca2+ transport in mussel mitochondria compared to approximately 1.0 nmole La3+ mg protein-1 in rat liver mitochondria. It is concluded that mussel mitochondria possess a comparable Ca2+ transporter to vertebrate mitochondria and possible reasons for resistance to La3+ are discussed.
Collapse
|
10
|
O'Byrne-Ring N, Behan A, Duke E. Mitochondrial calcium flux in temperature-sensitive mutants of. J Therm Biol 1981. [DOI: 10.1016/0306-4565(81)90006-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
|
11
|
McCormack JG, Denton RM. A comparative study of the regulation of Ca2+ of the activities of the 2-oxoglutarate dehydrogenase complex and NAD+-isocitrate dehydrogenase from a variety of sources. Biochem J 1981; 196:619-24. [PMID: 7032511 PMCID: PMC1163036 DOI: 10.1042/bj1960619] [Citation(s) in RCA: 82] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Ca2+ was shown to activate oxoglutarate dehydrogenase and NAD+-isocitrate dehydrogenase from heart and other rat tissues by markedly decreasing the Km values of the enzymes for their respective substrates [see Denton & McCormack (1980) FEBS Lett. 119, 1-8]. Similar effects of Ca2+ were observed in the present study with both enzymes from other vertebrate sources (pigeon, trout, frog and human heart), but not with the enzymes from blowfly or locust flight muscle, or potato or Escherichia coli. In contrast, the Km values of the oxoglutarate dehydrogenases were affected by ADP, ATP and H+ to a similar extent in every case, except for the enzyme from E. coli, which was not sensitive to regulation by these agents.
Collapse
|
12
|
|
13
|
Smith RL, Bygrave FL. Enrichment of ruthenium red-sensitive Ca2+ transport in a population of heavy mitochondria isolated from flight-muscle of Lucilia cuprina. Further evidence for its heterogeneous distribution in the inner mitochondrial membrane. FEBS Lett 1978; 95:303-6. [PMID: 720623 DOI: 10.1016/0014-5793(78)81016-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
|
14
|
Bygrave FL, Heaney TP, Ramachandran C. Submitochondrial location of ruthenium red-sensitive calcium-ion transport and evidence for its enrichment in a specific population of rat liver mitochondria. Biochem J 1978; 174:1011-9. [PMID: 728072 PMCID: PMC1186007 DOI: 10.1042/bj1741011] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
1. Seven fractions sedimenting at between 3000 and 120000g-min were prepared from a rat liver homogenate by differential centrifugation in buffered iso-osmotic sucrose. The following measurements were carried out on each of these fractions: Ruthenium Red-sensitive Ca(2+) transport in the absence and in the presence of P(i) as well as in the presence of N-ethylmaleimide to prevent P(i) cycling, succinate-supported respiration in the absence and in the presence of ADP, the DeltaE and -59 DeltapH components of the protonmotive force, cytochrome oxidase, uncoupler-stimulated adenosine triphosphatase, alpha-glycerophosphate dehydrogenase, P(i) content and the effect on the ;resting' rate of respiration of repeated additions of a fixed Ca(2+) concentration. 2. Ca(2+) transport either in the presence or in the absence of added P(i) and in the presence of N-ethylmaleimide exhibits significantly higher rates in the fraction sedimenting at 8000g-min. By contrast, respiration in the presence or in the absence of added ADP and the values for DeltaE and -59 DeltapH were similar in those fractions sedimenting between 4000 and 20000g-min, indicating that the driving force for Ca(2+) transport was similar in each of these fractions. 3. Experiments designed to determine the capacity of the individual fractions for Ca(2+), as measured by the effect of repeated additions of Ca(2+) on the resting rate of respiration, showed that fraction 2, i.e. that sedimenting at 8000g-min, also exhibited the greatest tolerance towards the uncoupling action of the ion. 4. Of the three enzyme activity profiles, only that of alpha-glycerophosphate dehydrogenase was similar to that of Ca(2+) transport. Because previous workers have assigned this enzyme to loci in the inner peripheral membrane [Werner & Neupert (1972) Eur. J. Biochem.25, 379-396], it is concluded that the Ruthenium Red-sensitive Ca(2+)- transport system also is located in this domain of the inner membrane. The relation of these findings to the mechanisms of mitochondrial Ca(2+) transport and the biogenesis of mitochondria is discussed.
Collapse
|
15
|
Bygrave FL, Smith RL. Inability of tributyltin-induced chloride/hydroxyl exchange to stimulate calcium transport in mitochondria isolated from flight muscle of the sheep blowfly Lucilia cuprina. Biochem J 1978; 174:1075-7. [PMID: 728076 PMCID: PMC1186016 DOI: 10.1042/bj1741075] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Tributyltin in the concentration range 1-4mum failed to stimulate Ca(2+) transport by Lucilia flight-muscle mitochondria in a medium containing KCl and respiratory substrate but devoid of P(i), despite its promotion of a rapid Cl(-)/OH(-) exchange. When 2mm-P(i) was present, concentrations of tributyltin greater than 1mum inhibited the initial rate of Ca(2+) transport and induced efflux of the ion from the mitochondria in Cl(-)- or NO(3) (-)-containing media. Lower concentrations had little effect. Oligomycin added at up to 10mug/mg of mitochondrial protein had no effect on Ca(2+) transport. By contrast, approx. 0.3mum-tributyltin completely inhibited respiration supported by alpha-glycerophosphate in either the presence or absence of added ADP. The data suggest that tributyltin can inhibit Ca(2+) transport in Lucilia flight-muscle mitochondria other than by facilitating a Cl(-)/OH(-) exchange or producing an oligomycin-like effect.
Collapse
|
16
|
Nicholls DG. Calcium transport and porton electrochemical potential gradient in mitochondria from guinea-pig cerebral cortex and rat heart. Biochem J 1978; 170:511-22. [PMID: 348200 PMCID: PMC1183926 DOI: 10.1042/bj1700511] [Citation(s) in RCA: 247] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
A method is described for the preparation of ;free' and ;synaptosomal' brain mitochondria from fractions of guinea-pig cerebral cortex respectively depleted and enriched in synaptosomes. Both preparations of mitochondria have a low membrane H(+) conductance, a high capacity to phosphorylate ADP, and a capacity to accumulate Ca(2+) at rates limited by the activity of the respiratory chain. Ca(2+) transport by ;free' brain mitochondria is compared with that of heart mitochondria. The Ca(2+) conductance of ;free' brain mitochondria was at least 20 times that for rat heart mitochondria. Ca(2+) uptake by brain mitochondria increased the pH gradient and decreased membrane potential, whereas little change occurred during the much slower uptake by heart mitochondria. In the presence of ionophore A23187, dissipative Ca(2+) cycling decreased the H(+) electrochemical potential gradient of brain mitochondria from 190 to 60mV, but caused only a slight decrease with heart mitochondria, although the ionophore lowered the pH gradient and increased membrane potential. The Ca(2+) conductance of ;free' brain mitochondria is distinctive in showing a hyperbolic dependency on free Ca(2+) concentration. In the presence of Ruthenium Red, a rapid Na(+)-dependent Ca(2+) efflux occurs. The H(+) electrochemical potential gradient is maintained during this efflux, and membrane potential increases, with both ;free' brain and heart mitochondria. The Na(+) requirement for Ca(2+) efflux appears not to be related to the high Na(+)/H(+) exchange activity but may represent a direct exchange of Na(+) for Ca(2+).
Collapse
|
17
|
|
18
|
Smith RL, Bygrave FL. Changes in the response of mitochondrial calcium transport to exogenous phosphate during development in flight muscle of the sheep blowfly Lucilla cuprina. Biochem J 1978; 170:81-5. [PMID: 629784 PMCID: PMC1183863 DOI: 10.1042/bj1700081] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
1. Ca2+ transport by mitochondria isolated from flight muscle of the sheep blowfly Lucilla cuprina does not occur in the absence of added P1. Maximum rates of transport are attained when about 2.5 mM-phosphate is present. 2. As mitochondria develop, high but not low phosphate concentrations begin to inhibit Ca2+ transport markedly; those isolated from 2-day-old flies for example, are inhibited by about 75% by 20 mM-phosphate. Maximum rates of transport, i.e. those measured in the presence of 2.5 mM-phosphate, begin to decline only when the fly is about 3 days old. 3. Mitochondrial phosphate transport activity does not change during development of the blowfly, but the endogenous concentration of the anion does. At emergence it is about 6nmol/mg of protein, increases to about 17 nmol/mg of protein at 2-3h and then rapidly declines to reach less than 5 nmol/mg of protein after 2 days of adult life. 4. Studies on the effect of phosphate on oxidation of alpha-glycerophosphate in the absence and presence of ADP reveal a lack of inhibition by high phosphate concentrations indicating that the anion does not influence Ca2+ transport by preventing the generation of the proton electrochemical gradient across the inner membrane. 5. It is concluded that the molecular assembly in the inner membrane of Lucilla mitochondria responsible for transporting Ca2+ is fully developed at emergence and remains so for at least 2-3 days of adult life. The possibility exists that Ca2+-transport activity in these mitochondria is controlled at least in part by P1.
Collapse
|
19
|
Carafoli E, Crompton M. The Regulation of Intracellular Calcium. CURRENT TOPICS IN MEMBRANES AND TRANSPORT 1978. [DOI: 10.1016/s0070-2161(08)60835-7] [Citation(s) in RCA: 241] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
|
20
|
Greenway DC, Himms-Hagen J. Increased calcium uptake by muscle mitochondria of cold-acclimated rats. Am J Physiol Cell Physiol 1978; 234:C7-13. [PMID: 203194 DOI: 10.1152/ajpcell.1978.234.1.c7] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Skeletal muscle mitochondria of cold-acclimated rats have an altered morphology that is related to the occurrence of nonshivering thermogenesis. The transport of calcium by these mitochondria was studied in a search for an alteration in an energy-dissipating mechanism which might be related to the altered morphology and to the altered mode of thermogenesis in the cold-acclimated animal. The rates of calcium uptake, of calcium-stimulated respiration, and of state 4 respiration after calcium uptake were increased in the altered mitochondria. The capacity to accumulate calcium without phosphate was increased, whereas with phosphate all the calcium was removed from the medium and no difference in total uptake was seen. Spontaneous release of calcium was greater but sodium-induced release was unchanged. No effect of cyclic AMP or prostaglandin E1 on release of calcium was seen. The increase in rate of calcium uptake occurred gradually during the first 3-5 wk of acclimation to cold. The results are considered to give some support to the hypothesis that adaptive changes in the mitochondrial calcium transport cycle in skeletal muscle occur during acclimation to cold.
Collapse
|
21
|
Bygrave FL, Smith RL. Dietary-induced modification of calcium transport in mitochondria isolated from flight-muscle of developing sheep blowfly Lucilia cuprina. Biochem Biophys Res Commun 1977; 79:154-8. [PMID: 921793 DOI: 10.1016/0006-291x(77)90073-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
|
22
|
Bygrave FL, Ramachandran C, Smith RL. On the mechanism by which inorganic phosphate stimulates mitochondrial calcium transport. FEBS Lett 1977; 83:155-8. [PMID: 923818 DOI: 10.1016/0014-5793(77)80663-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
|
23
|
|
24
|
|
25
|
|
26
|
Heaton GM, Nicholls DG. The calcium conductance of the inner membrane of rat liver mitochondria and the determination of the calcium electrochemical gradient. Biochem J 1976; 156:635-46. [PMID: 949345 PMCID: PMC1163798 DOI: 10.1042/bj1560635] [Citation(s) in RCA: 126] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
1. A method is described for establishing steady-state conditions of calcium transport across the inner membrane of rat liver mitochondria and for determining the current of Ca2+ flowing across the membrane, together with the Ca2+ electrochemical gradient across the native Ca2+ carrier. These parameters were used to quantify the apparent Ca2+ conductance of the native carrier. 2. At 23 degrees C and pH7.0, the apparent Ca2+ conductance of the carrier is close to 1 nmol of Ca2+-min-1-mg of protein-1 mV-1. Proton extrusion by the respiratory chain, rather than the Ca2+ carrier itself, may often be rate-limiting in studies of initial rates of Ca2+ uptake. 3. Under parallel conditions, the endogenous H+ conductance of the membrane is 0.3 nmol of H+-min-1-mg of protein-1-mV-1. 4. Ruthenium Red and La3+ both strongly inhibit the Ca2+ conductance of the carrier, but are without effect on the H+ conductance of the membrane. 5. The apparent Ca2+ conductance of the carrier shows a sigmoidal dependence on the activity of Ca2+ in the medium. At 23 degrees C and pH7.2, half-maximum conductance is obtained at a Ca2+ activity of 4.7 muM. 6. The apparent Ca2+ conductance and the H+ conductance of the inner membrane increase fourfold from 23 degrees to 38 degrees C. The apparent Arrhenius activation energy for Ca2+ transport is 69kJ/mol. The H+ electrochemical gradient maintained in the absence of Ca2+ transport does not vary significantly with temperature. 7. The apparent Ca2+ conductance increases fivefold on increasing the pH of the medium from 6.8 to 8.0. The H+ conductance of the membrane does not vary significantly with pH over this range. 8. Mg2+ has no effect on the apparent Ca2+ conductance when added at concentration up to 1 mM. 9. Results are compared with classical methods of studying Ca2+ transport across the mitochondrial inner membrane.
Collapse
|
27
|
Dorman DM, Barritt GJ, Bygrave FL. Stimulation of hepatic mitochondrial calcium transport by elevated plasma insulin concentrations. Biochem J 1975; 150:389-95. [PMID: 1212198 PMCID: PMC1165753 DOI: 10.1042/bj1500389] [Citation(s) in RCA: 39] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The effect of insulin (injected intraperitoneally) on the transport of Ca2+ by hepatic mitochondria from rats was investigated. 2. Elevated concentrations of plasma insulin within the physiological range (10-100muunits/ml) stimulate the initial rate of Ca2+ transport into mitochondria at 4 degrees C by about 75% and prolong by approx. tenfold the time for which the mitochondria retain the accumulated Ca2+. 3. The prolonged retention of Ca2+ is observed under the conditions where hypoglycaemia is significantly decreased by the simultaneous injection of glucose and insulin. 4. A good correlation is observed between the effects on Ca2+ transport and the decrease in blood glucose concentration when the amount of insulin injected was varied. 5. The effects of insulin on mitochondrial Ca2+ transport are apparent at about 30 min after the injection, and are inhibited by cycloheximide. 6. There is little change in mitochondrial energy transduction after the administration of insulin. 7. The results are briefly discussed in relation to the mechanisms of Ca2+ transport across the inner mitochondrial membrane and the role of mitochondria in modifying intracellular Ca2+ concentrations with reference to the mechanism(s) by which insulin affects cellular metabolism.
Collapse
|
28
|
Thorne RF, Bygrave FL. Kinetic evidence for calcium-ion and phosphate-ion transport systems in mitochondria from Ehrlich ascites tumour cells. FEBS Lett 1975; 56:185-8. [PMID: 1157937 DOI: 10.1016/0014-5793(75)81087-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
|
29
|
Reed KC, Bygrave FL. A kinetic study of mitochondrial calcium transport. EUROPEAN JOURNAL OF BIOCHEMISTRY 1975; 55:497-504. [PMID: 240699 DOI: 10.1111/j.1432-1033.1975.tb02187.x] [Citation(s) in RCA: 102] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
This report describes a kinetic analysis of energy-linked Ca2+ transport in rat liver mitochondria, in which a ruthenium red/EGTA [ethanedioxy-bis(ethylamine)-tetraacetic acid] quenching technique has been used to measure rates of 45Ca2+ transport. Accurately known concentrations of free 45Ca2+ were generated with Ca2+/nitrilotriacetic acids buffers for the determination of substrate/velocity relationships. The results show that the initial velocity of transport is a sigmoidal function of Ca2+ concentration (Hill coefficient = 1.7), the Km being 4 muM Ca4 at 0 degrees C and pH 7.4. These values for the Hill coefficient and the Km remain constant in the presence of up to 2 mM phosphate, but with 10 mM acetate both parameters are increased slightly. Both permeant acids increase the maximum velocity to an extent dependent on their concentration. The Ca2+-binding site(s) of the carrier contains a group ionizing at pH approximately 7.5 at 0 degrees C, which is functional in the dissociated state. The stimulatory effect of permeant acids is ascribed to their facilitating the release of Ca2+ from the carrier to the internal phase, an interpretation which is strengthened by the lack of effect of the permeant anion SCN- on Ca2+ transport. Studies on the time-course of Ca2+ uptake and of EFTA-induced Ca2+ efflux from pre-loaded mitochondria demonstrate the reversibility of the carrier in respiring mitochondria and the extent to which this property is influenced by permeant acids. These data are accommodated in a carrier mechanism based on electrophoretic transport of Ca2+ bound to pairs of interacting acidic sites.
Collapse
|
30
|
Doy FA, Daday AA, Bygrave FL. Synchronous appearance of adenine nucleotide translocase activity and oxidative phosphorylation in mitochondria from flight-muscle of the developing sheep blowfly, Lucilia cuprina. FEBS Lett 1975; 54:245-8. [PMID: 1132511 DOI: 10.1016/0014-5793(75)80084-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
|