scholarly journals The uptake of silicic acid by rat liver mitochondria

1978 ◽  
Vol 172 (3) ◽  
pp. 557-568 ◽  
Author(s):  
R N Johnson ◽  
B E Volcani
Keyword(s):  
Silicic Acid ◽  
Diffusion Mechanism ◽  
Mitochondrial Protein ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Energy Status ◽  
Matrix Space ◽  
Inner Membrane ◽  
Simple Diffusion ◽  
Mitochondrial Inner Membrane

1. To gain insight into a putative role for mitochondria in silicon metabolism, mitochondrial uptake (by which it is meant the removal from the medium) of silicic acid [Si(OH)4] was studied under conditions minimizing SI(OH)4 polymerization. 2. Measurements of mitochondrial respiration and swelling indicated indirectly a significant uptake of Si(OH)4 as a weak acid, but this was not confirmed when 31Si(OH)4 was used as a tracer. 31Si(OH)4 occupied a mitochondrial volume similar to that of 3H2O and was relatively unaffected by mitochondrial energy status and by the pH gradient across the mitochondrial inner membrane. 3. Uptake was directly proportional to Si(OH)4 concentration in the range 0-3 mM. 4. The uptake consisted of two components: under all conditions examined, the greater quantity, amounting to 1-2nmol of Si(OH)4/mg of mitochondrial protein, was bound, a major portion of it external to the inner membrane, with the lesser quantity free within the matrix space. 5. Equilibration of 31Si(OH)4 between medium and matrix was a slow process, having a half-time of approx. 10 min at 22 degrees C. 6. Mersalyl and N-ethylmaleimide inhibited the uptake by preferentially lowering the amount of Si(OH)4 bound. Their action was somewhat variable, depending on the precise nature of the suspending medium, and suggesting that the bound material may represent polymerized forms of Si(OH)4. 7. It is concluded that Si(OH)4 may penetrate the mitochondrial inner membrane by a simple diffusion mechanism.

scholarly journals ‘Pore’ formation is not required for the hydroperoxide-induced Ca2+ release from rat liver mitochondria

1992 ◽  
Vol 285 (1) ◽  
pp. 65-69 ◽  
Author(s):  
J Schlegel ◽  
M Schweizer ◽  
C Richter
Keyword(s):  
Rat Liver ◽  
Pore Formation ◽  
Permeability Transition Pore ◽  
Permeability Transition ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Inner Membrane ◽  
Mitochondrial Inner Membrane ◽  
Specific Permeability ◽  
Specific Pathway

It has recently been suggested by several investigators that the hydroperoxide- and phosphate-induced Ca2+ release from mitochondria occurs through a non-specific ‘pore’ formed in the mitochondrial inner membrane. The aim of the present study was to investigate whether ‘pore’ formation actually is required for Ca2+ release. We find that the t-butyl hydroperoxide (tbh)-induced release is not accompanied by stimulation of sucrose entry into, K+ release from, and swelling of mitochondria provided re-uptake of the released Ca2+ (‘Ca2+ cycling’) is prevented. We conclude that (i) the tbh-induced Ca2+ release from rat liver mitochondria does not require ‘pore’ formation in the mitochondrial inner membrane, (ii) this release occurs via a specific pathway from intact mitochondria, and (iii) a non-specific permeability transition (‘pore’ formation) is likely to be secondary to Ca2+ cycling by mitochondria.

scholarly journals Stable enhancement of calcium retention in mitochondria isolated from rat liver after the administration of glucagon to the intact animal

1978 ◽  
Vol 176 (3) ◽  
pp. 705-714 ◽  
Author(s):  
Veronica Prpić ◽  
Terry L. Spencer ◽  
Fyfe L. Bygrave
Keyword(s):  
Rat Liver ◽  
Molecular Mechanisms ◽  
Adenine Nucleotide ◽  
Adenine Nucleotides ◽  
Mitochondrial Protein ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Matrix Space ◽  
The Matrix

1. Mitochondria isolated from rat liver by centrifugation of the homogenate in buffered iso-osmotic sucrose at between 4000 and 8000g-min, 1h after the administration in vivo of 30μg of glucagon/100g body wt., retain Ca2+ for over 45min after its addition at 100nmol/mg of mitochondrial protein in the presence of 2mm-Pi. In similar experiments, but after the administration of saline (0.9% NaCl) in place of glucagon, Ca2+ is retained for 6–8min. The ability of glucagon to enhance Ca2+ retention is completely prevented by co-administration of 4.2mg of puromycin/100g body wt. 2. The resting rate of respiration after Ca2+ accumulation by mitochondria from glucagon-treated rats remains low by contrast with that from saline-treated rats. Respiration in the latter mitochondria increased markedly after the Ca2+ accumulation, reflecting the uncoupling action of the ion. 3. Concomitant with the enhanced retention of Ca2+ and low rates of resting respiration by mitochondria from glucagon-treated rats was an increased ability to retain endogenous adenine nucleotides. 4. An investigation of properties of mitochondria known to influence Ca2+ transport revealed a significantly higher concentration of adenine nucleotides but not of Pi in those from glucagon-treated rats. The membrane potential remained unchanged, but the transmembrane pH gradient increased by approx. 10mV, indicating increased alkalinity of the matrix space. 5. Depletion of endogenous adenine nucleotides by Pi treatment in mitochondria from both glucagon-treated and saline-treated rats led to a marked diminution in ability to retain Ca2+. The activity of the adenine nucleotide translocase was unaffected by glucagon treatment of rats in vivo. 6. Although the data are consistent with the argument that the Ca2+-translocation cycle in rat liver mitochondria is a target for glucagon action in vivo, they do not permit conclusions to be drawn about the molecular mechanisms involved in the glucagon-induced alteration to this cycle.

scholarly journals Cholesterol increase in mitochondria: its effect on inner-membrane functions, submitochondrial localization and ultrastructural morphology

1993 ◽  
Vol 289 (3) ◽  
pp. 703-708 ◽  
Author(s):  
S Echegoyen ◽  
E B Oliva ◽  
J Sepulveda ◽  
J C Díaz-Zagoya ◽  
M T Espinosa-García ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Atpase Activity ◽  
Succinate Dehydrogenase ◽  
Outer Membrane ◽  
Rat Liver ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Inner Membrane ◽  
Ultrastructural Morphology ◽  
Mitochondrial Inner Membrane

The effect of cholesterol incorporation on some functions of the mitochondrial inner membrane and on the morphology of rat liver mitochondria was studied. Basal ATPase and succinate dehydrogenase activities remained unchanged after cholesterol was incorporated into the mitochondria; however, uncoupled ATPase activity was partially inhibited. The presence of several substrates and inhibitors did not change the amount of cholesterol incorporated, which was localized mostly in the outer membrane. Electron-microscope observations revealed the presence of vesicles between the outer and inner membranes; these vesicles increased in number with the amount of cholesterol incorporated. The data suggest that cholesterol induces the formation of vesicles from the outer membrane, and modifies the activity of stimulated ATPase.

scholarly journals d-Lactate transport and metabolism in rat liver mitochondria

2002 ◽  
Vol 365 (2) ◽  
pp. 391-403 ◽  
Author(s):  
Lidia de BARI ◽  
Anna ATLANTE ◽  
Nicoletta GUARAGNELLA ◽  
Giovanni PRINCIPATO ◽  
Salvatore PASSARELLA
Keyword(s):  
Lactate Dehydrogenase ◽  
Rat Liver ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Lactate Metabolism ◽  
Inner Membrane ◽  
Mitochondrial Inner Membrane ◽  
The Matrix ◽  
Inside Out

In the present study we investigated whether isolated rat liver mitochondria can take up and metabolize d-lactate. We found the following: (1) externally added d-lactate causes oxygen uptake by mitochondria [P/O ratio (the ratio of mol of ATP synthesized to mol of oxygen atoms reduced to water during oxidative phosphorylation) = 2] and membrane potential (Δψ) generation in processes that are rotenone-insensitive, but inhibited by antimycin A and cyanide, and proton release from coupled mitochondria inhibited by α-cyanocinnamate, but not by phenylsuccinate; (2) the activity of the putative flavoprotein (d-lactate dehydrogenase) was detected in inside-out submitochondrial particles, but not in mitochondria and mitoplasts, as it is localized in the matrix phase of the mitochondrial inner membrane; (3) three novel separate translocators exist to mediate d-lactate traffic across the mitochondrial inner membrane: the d-lactate/H+ symporter, which was investigated by measuring fluorimetrically the rate of endogenous flavin reduction, the d-lactate/oxoacid antiporter (which mediates both the d-lactate/pyruvate and d-lactate/oxaloacetate exchanges) and d-lactate/malate antiporter studied by monitoring photometrically the appearance of the d-lactate counteranions outside mitochondria. The d-lactate translocators, in the light of their different inhibition profiles separate from the monocarboxylate carrier, were found to differ from each other in the Vmax values and in the inhibition and pH profiles and were shown to regulate mitochondrial d-lactate metabolism in vitro. The d-lactate translocators and the d-lactate dehydrogenase could account for the removal of the toxic methylglyoxal from cytosol, as well as for d-lactate-dependent gluconeogenesis.

scholarly journals Biochemical effects of the hypoglycaemic compound diphenyleneiodonium. Catalysis of anion–hydroxyl ion exchange across the inner membrane of rat liver mitochondria and effects on oxygen uptake

1972 ◽  
Vol 129 (1) ◽  
pp. 39-54 ◽  
Author(s):  
P. C. Holland ◽  
H. S. A. Sherratt
Keyword(s):  
Rat Liver ◽  
Indirect Evidence ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Inner Membrane ◽  
Mitochondrial Inner Membrane ◽  
Hydroxyl Ion ◽  
Respiration Of Mitochondria ◽  
Free Media ◽  
Stimulation Of

1. The hypoglycaemic compound diphenyleneiodonium causes rapid and extensive swelling of rat liver mitochondria suspended in 150mm-NH4Cl, and in 150mm-KCl in the presence of 2,4-dinitrophenol and valinomycin. This indicates that diphenyleneiodonium catalyses a compulsory exchange of OH-for Cl-across the mitochondrial inner membrane. Br-and SCN-were the only other anions found whose exchange for OH-is catalysed by diphenyleneiodonium. 2. Diphenyleneiodonium inhibited state 3 respiration of mitochondria and slightly stimulated state 4 respiration with succinate or glutamate as substrate in a standard Cl--containing medium. 3. Diphenyleneiodonium did not inhibit state 3 respiration significantly in two Cl--free media (based on glycerol 2-phosphate or sucrose) but caused some stimulation of state 4. 4. In Cl--containing medium diphenyleneiodonium only slightly inhibited the 2,4-dinitrophenol-stimulated adenosine triphosphatase and it had little effect in the absence of Cl-. 5. The inhibition of respiration in the presence of Cl-is dependent on the Cl-–OH-exchange. 2,4-Dichlorodiphenyleneiodonium is ten times as active as diphenyleneiodonium both in causing swelling of mitochondria suspended in 150mm-NH4Cl and in inhibiting state 3 respiration in Cl--containing medium. Indirect evidence suggests that the Cl-–OH-exchange impairs the rate of uptake of substrate anions. 6. It is proposed that stimulation of state 4 respiration in the absence of Cl-depends, at least in part, on an electrogenic uptake of diphenyleneiodonium cations. 7. Tripropyl-lead acetate, methylmercuric iodide and nine substituted diphenyleneiodonium derivatives also catalyse Cl-–OH-exchange across the mitochondrial membrane. 8. Diphenyleneiodonium is compared with the trialkyltin compounds, which are also known to mediate Cl-–OH-exchange and which have in addition strong oligomycin-like effects on respiration. It is concluded that diphenyleneiodonium is specific for catalysing anion–OH-exchange and will be a useful reagent for investigating membrane-dependent systems.

scholarly journals Partial purification and properties of rat liver mitochondrial polynucleotide phosphorylase

1972 ◽  
Vol 130 (2) ◽  
pp. 343-353 ◽  
Author(s):  
Y. P. See ◽  
P. S. Fitt
Keyword(s):  
Rat Liver ◽  
Kinase Activity ◽  
Liver Mitochondria ◽  
Partial Purification ◽  
Rat Liver Mitochondria ◽  
Polynucleotide Phosphorylase ◽  
Inner Membrane ◽  
Mitochondrial Inner Membrane ◽  
Purification And Properties ◽  
Exchange Activity

1. Polynucleotide phosphorylase was partially purified from the inner membrane of rat liver mitochondria. 2. The partially purified particulate enzyme catalyses phosphorolysis of poly(A), poly(C), poly(U) and RNA to nucleoside diphosphates. 3. It is devoid of nucleoside diphosphate-polymerization activity. 4. Variable amounts of ADP/Pi-exchange activity are associated with the polynucleotide phosphorylase and are probably due to a different enzyme. 5. ADP is the preferred substrate for exchange, and little or no reaction occurs with other nucleoside diphosphates, but ATP/Pi-exchange takes place at one-third the rate observed with ADP. 6. The partially purified enzyme is free from the phosphatases found in the crude mitochondrial inner membrane, but is associated with an endonuclease activity and some adenylate kinase activity; no cytidylate kinase activity analogous to the latter was detectable.

scholarly journals Evolution of energy metabolism. Proton permeability of the inner membrane of liver mitochondria is greater in a mammal than in a reptile

1991 ◽  
Vol 275 (1) ◽  
pp. 81-86 ◽  
Author(s):  
M D Brand ◽  
P Couture ◽  
P L Else ◽  
K W Withers ◽  
A J Hulbert
Keyword(s):  
Metabolic Rate ◽  
Mitochondrial Membrane ◽  
Mitochondrial Protein ◽  
Rat Hepatocytes ◽  
Liver Mitochondria ◽  
Standard Metabolic Rate ◽  
Proton Permeability ◽  
Inner Membrane ◽  
Mitochondrial Inner Membrane ◽  
Bearded Dragon

Standard metabolic rate is 7-fold greater in the rat (a typical mammal) than in the bearded dragon, Amphibolurus vitticeps (a reptile with the same body mass and temperature). Rat hepatocytes respire 4-fold faster than do hepatocytes from the lizard. The inner membrane of isolated rat liver mitochondrial has a proton permeability that is 4-5-fold greater than the proton permeability of the lizard liver mitochondrial membrane per mg of mitochondrial protein. The greater permeability of rat mitochondria is not caused by differences in the surface area of the mitochondrial inner membrane, but differences in the fatty acid composition of the mitochondrial phospholipids may be involved in the permeability differences. Greater proton permeability of the mitochondrial inner membrane may contribute to the greater standard metabolic rate of mammals.

Electron Microscopic Tomography of Cellular Organelles: Chemical Fixation Vs. Cryo-Substitution of Rat-Liver Mitochondria

1998 ◽  
Vol 4 (S2) ◽  
pp. 430-431
Author(s):  
C.A. Mannella ◽  
K. Buttle ◽  
K. Tessitore ◽  
B.K. Rath ◽  
C. Hsieh ◽  
...  
Keyword(s):  
Rat Liver ◽  
3D Structure ◽  
Design Feature ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Electron Microscopic ◽  
Inner Membrane ◽  
Low Contrast ◽  
Mitochondrial Inner Membrane ◽  
Cellular Organelles

Electron microscopic tomography is proving to be a valuable tool for investigating the 3D structure and organization of cellular organelles. Important progress is being made in the application of the technique to frozen-hydrated material, but it is likely that success with thick specimens will be limited by the low contrast and beam sensitivity of naked biological material. Thus, optimizing procedures for fixing, embedding, staining, and selectively labelling cells for 3D electron microscopy remains a priority.Tomography of chemically fixed and plastic-embedded rat-liver tissue and isolated mitochondria has shown that the cristae (the invaginations of the mitochondrial inner membrane) are pleiomorphic and connected to each other and to the surface of the inner membrane by tubular regions 30-40 nm in diameter. This basic design feature has important implications for the microcompartmentation of ions and molecules within this organelle.

scholarly journals The distribution and chemical nature of radioactive folates in rat liver cells and rat liver mitochondria

1979 ◽  
Vol 178 (3) ◽  
pp. 651-659 ◽  
Author(s):  
R J Cook ◽  
J A Blair
Keyword(s):  
Oral Administration ◽  
Rat Liver ◽  
Subcellular Fractionation ◽  
Liver Mitochondria ◽  
Liver Cells ◽  
Rat Liver Mitochondria ◽  
Inner Membrane ◽  
Mitochondrial Inner Membrane ◽  
Rat Liver Cells ◽  
Cell Cytosol

Subcellular fractionation of rat liver cells revealed that a mixture of 14C- and 3H-labelled folic acid was distributed approximately equally between the mitochondria and cytosol 2, 24, 48 and 72 h after oral administration. Subfractionation of liver mitochondria 48 h after oral administration showed that the radioactivity was mainly associated with the inner membrane (27.7%) and matrix (51.5%). Hot-ascorbate extraction of the cell cytosol, mitochondrial inner membrane and matrix showed the majority of folates were present as polyglutamates. Acid treatment of isolated folates from cytosol, inner membrane and matrix produced breakdown products consistent with scission of tetrahydrofolates. The folates isolated in the mitochondrial matrix were bound to protein that had an estimated mol. wt. of 90,000.

scholarly journals Altered release of carnitine palmitoyltransferase activity by digitonin from liver mitochondria of rats in different physiological states

1985 ◽  
Vol 230 (2) ◽  
pp. 389-394 ◽  
Author(s):  
V A Zammit ◽  
C G Corstorphine
Keyword(s):  
Liver Mitochondria ◽  
Diabetic Rats ◽  
Carnitine Palmitoyltransferase ◽  
Rat Liver Mitochondria ◽  
Intermembrane Space ◽  
Marker Enzyme ◽  
Inner Membrane ◽  
Mitochondrial Inner Membrane ◽  
Cpt I ◽  
Carnitine Palmitoyltransferase Activity

The release of carnitine palmitoyltransferase (CPT) activity from rat liver mitochondria by increasing concentrations of digitonin was studied for mitochondrial preparations from fed, 48 h-starved and diabetic animals. A bimodal release of activity was observed only for mitochondria isolated from starved and, to a lesser degree, from diabetic rats, and it appeared to result primarily from the enhanced release of approx. 40% and 60%, respectively, of the total CPT activity. This change in the pattern of release was specific to CPT among the marker enzymes studied. For all three types of mitochondria there was no substantial release of CPT concurrently with that of the marker enzyme for the soluble intermembrane space, adenylate kinase. These results illustrate that the bimodal pattern of release of CPT reported previously for mitochondria from starved rats [Bergstrom & Reitz (1980) Arch. Biochem. Biophys. 204, 71-79] is not an immutable consequence of the localization of CPT activity on either side of the mitochondrial inner membrane. Sequential loss of CPT I (i.e. the overt form) from the mitochondrial inner membrane did not affect the concentration of malonyl-CoA required to effect fractional inhibition of the CPT I that remained associated with the mitochondria. The results are discussed in relation to the possibility that altered enzyme-membrane interactions may account for some of the altered regulatory properties of CPT I in liver mitochondria of animals in different physiological states.

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