scholarly journals Studies on the Mechanism of Ascorbate-induced Swelling and Lysis of Isolated Liver Mitochondria

1964 ◽  
Vol 239 (2) ◽  
pp. 604-613 ◽  
Author(s):  
F. Edmund Hunter ◽  
A. Scott ◽  
P.E. Hoffsten ◽  
Francisco Guerra ◽  
J. Weinstein ◽  
...  
Keyword(s):  
Liver Mitochondria ◽  
Isolated Liver

scholarly journals Stability of Oxidative Phosphorylation and Related Reactions in Isolated Liver Mitochondria

1959 ◽  
Vol 234 (6) ◽  
pp. 1580-1586 ◽  
Author(s):  
Eugene C. Weinbach ◽  
With the technical assistance of C. Elwood Claggett
Keyword(s):  
Oxidative Phosphorylation ◽  
Liver Mitochondria ◽  
Isolated Liver

scholarly journals EFFECT OF GAMMA IRRADIATION ON THE DESOXYRIBONUCLEASE II ACTIVITY OF ISOLATED MITOCHONDRIA

1957 ◽  
Vol 3 (2) ◽  
pp. 239-248 ◽  
Author(s):  
Shigefumi Okada ◽  
Lee D. Peachey
Keyword(s):  
Structural Damage ◽  
Liver Homogenate ◽  
Liver Mitochondria ◽  
Structural Elements ◽  
Dnase Ii ◽  
Mitochondrial Structure ◽  
Co60 Source ◽  
Mitochondrial Suspension ◽  
High Doses ◽  
Isolated Liver

1. Exposure of isolated liver mitochondria to high doses of gamma rays from a Co60 source causes the level of DNase II activity to increase. Treatment of the mitochondria with sonic vibration causes a further elevation of the activity to a level which is independent of the prior radiation dose. 2. Such increased mitochondrial DNase II activity appears to be due to the "structural damage" of the subcellular particulates caused by the ionizing radiation. Other methods of disrupting the mitochondrial structure also cause increased DNase II activity. A causal relationship between the structural alteration and the increased enzymatic activity is postulated. 3. The DNase II activity appears to be closely associated with the structural elements of the mitochondria and remains associated with the fragments after irradiation. 4. Upon irradiation, the mitochondrial suspension releases ultraviolet-absorbing materials which are probably nucleotide in nature. 5. The possibility of localization of DNase activity in the lysosome fraction of de Duve (15) is discussed. It is felt that DNase II is at least in part a mitochondrial enzyme and that probably the conclusions drawn here would be applicable to any DNase II present in the lysosomes as well. 6. Irradiation of whole liver homogenate causes no increased DNase II activity. The experiments do not provide any information on the presence or action of protective substances in the homogenate.

Oxidation and Phosphorylation Reactions in Isolated Liver Mitochondria in Normal and Icteric Conditions

1966 ◽  
Vol 1 (4) ◽  
pp. 284-291 ◽  
Author(s):  
T. Scherstén ◽  
S. Björkerud ◽  
L. Jakoi ◽  
P. Björntorp
Keyword(s):  
Liver Mitochondria ◽  
Isolated Liver

scholarly journals Effects of 2-mercaptoacetate in isolated liver mitochondria in vitro. Competitive inhibition of 3-hydroxybutyrate dehydrogenase and depression of the β-oxidation pathway

1982 ◽  
Vol 206 (1) ◽  
pp. 53-59 ◽  
Author(s):  
F Bauché ◽  
D Sabourault ◽  
Y Giudicelli ◽  
J Nordmann ◽  
R Nordmann
Keyword(s):  
Fatty Acid ◽  
Fatty Acid Oxidation ◽  
Competitive Inhibition ◽  
Liver Mitochondria ◽  
Inhibitory Effect ◽  
Acid Oxidation ◽  
Membrane Bound ◽  
Energy Dependent ◽  
Isolated Liver

The effects of 2-mercaptoacetate on the respiration rates induced by different substrates were studied in vitro in isolated liver mitochondria. With palmitoyl-L-carnitine or 2-oxoglutarate as the substrate, the ADP-stimulated respiration (State 3) was dose-dependently inhibited by 2-mercaptoacetate. with glutamate or succinate as the substrate. State-3 respiration was only slightly inhibited by 2-mercaptoacetate. In contrast, the oxidation rate of 3-hydroxybutyrate was competitively inhibited by 2-mercaptoacetate in both isolated mitochondria and submitochondrial particles. In uncoupled mitochondria and in mitochondria in which ATP- and GTP-dependent acyl-CoA biosynthesis was inhibited, the inhibitory effect of 2-mercaptoacetate on palmitoyl-L-carnitine oxidation was abolished; under the same conditions, however, inhibition of 3-hydroxybutyrate oxidation by 2-mercaptoacetate still persisted. These results led to the following conclusions: 2-mercaptoacetate itself enters the mitochondrial matrix, inhibits fatty acid oxidation through a mechanism requiring an energy-dependent activation of 2-mercaptoacetate and itself inhibits 3-hydroxybutyrate oxidation through a competitive inhibition of the membrane-bound 3-hydroxybutyrate dehydrogenase. This study also strongly suggests that the compound responsible for the inhibition of fatty acid oxidation is 2-mercaptoacetyl-CoA.

Studies on the rapid stimulation of mitochondrial respiration by thyroid hormones

1992 ◽  
Vol 127 (6) ◽  
pp. 542-546 ◽  
Author(s):  
Ian O'Reilly ◽  
Michael P Murphy
Keyword(s):  
Pyruvate Dehydrogenase ◽  
Mitochondrial Respiration ◽  
Liver Mitochondria ◽  
Respiration Rates ◽  
Iodothyronine Deiodinases ◽  
Rapid Stimulation ◽  
Isolated Liver ◽  
Cytoplasmic Ribosomes ◽  
Stimulation Of

Injection of L-3,5-diiodothyronine (T2) into rats made hypothyroid by 6-n-propyl-2-thiouracil (PTU) increased the respiration rates of subsequently isolated liver mitochondria; this stimulation of respiration by T2 occurred in the presence of cycloheximide and is therefore independent of protein synthesis on cytoplasmic ribosomes. Injection of T3 into PTU-treated rats had a lesser effect than T2 on the respiration rates of subsequently isolated mitochondria; as PTU is an inhibitor of 5′-iodothyronine deiodinases, which convert T3 into T2 in vivo, the rapid stimulation of mitochondrial respiration by T3, which has been shown in a range of systems, may not be due directly to T3 itself, but may be mediated by its deiodination product T2. Injection of T2, or T3, into hypothyroid or euthyroid rats had no effect on the percentage activity of mitochondrial pyruvate hydrogenase assayed 30 min later. The amount of active pyruvate dehydrogenase is regulated by changes in mitochondrial calcium concentration and matrix ATP/ADP ratio; therefore these parameters are not persistently affected by treatment with T3 or T2. In addition, the total amount of pyruvate dehydrogenase present was the same in euthyroid and hypothyroid rats, indicating that the expression of this enzyme is not stringently controlled by thyroid hormone status.

scholarly journals The effect of glucagon treatment and starvation of virgin and lactating rats on the rates of oxidation of octanoyl-l-carnitine and octanoate by isolated liver mitochondria

1980 ◽  
Vol 190 (2) ◽  
pp. 293-300 ◽  
Author(s):  
Victor A. Zammit
Keyword(s):  
Fatty Acids ◽  
Tricarboxylic Acid Cycle ◽  
Atp Synthesis ◽  
Liver Mitochondria ◽  
Oxidation Rates ◽  
Consumption Rates ◽  
Mitochondrial Oxidation ◽  
Elevated Rate ◽  
Isolated Liver ◽  
Chain Fatty Acids

1. Oxygen-consumption rates owing to oxidation of octanoate or octanoylcarnitine by isolated mitochondria from livers of fed, starved and glucagon-treated virgin or 12-day-lactating animals were measured under State-3 and State-4 conditions, in the presence or absence of l-malate and inhibitors of tricarboxylic acid-cycle activity (malonate and fluorocitrate). 2. Mitochondria from fed lactating animals had a slightly lower rate of octanoylcarnitine oxidation than did those of fed virgin animals, whereas the rates of octanoate oxidation were unaffected. 3. Starvation of virgin animals for 24h or 48h resulted in a large (70–100%) increase in mitochondrial octanoylcarnitine oxidation; rates of octanoate oxidation were either unaffected (24 and 48h starvation in the absence of malonate and fluorocitrate) or diminished by 30% (48h starvation in the presence of inhibitors). In lactating animals, 24h starvation resulted in a smaller increase in the rate of octanoylcarnitine oxidation than that obtained for mitochondria from virgin rats. 4. Glucagon treatment (by intra-abdominal injection) of fed virgin and lactating rats increased the rate of mitochondrial oxidation of both octanoylcarnitine and octanoate. Injection of glucagon into 48h-starved virgin rats did not increase further the already elevated rate of octanoylcarnitine oxidation, but reversed the inhibition of octanoate β-oxidation observed for these mitochondria in the presence of malonate and fluorocitrate. 5. It is suggested that glucagon activates octanoylcarnitine oxidation by increasing the activity of the carnitine/acylcarnitine transport system [Parvin & Pande (1979) J. Biol. Chem.254, 5423–5429] and that the increase in octanoate oxidation by mitochondria from glucagon-treated animals is caused by the increased rate of ATP synthesis in these mitochondria. 6. The results are discussed in relation to the increased capacity of the liver to oxidize long-chain fatty acids and carnitine esters of medium-chain fatty acids under conditions characterized by increased ketogenesis.

Hepatic ammonia metabolism in a uricotelic treefrog Phyllomedusa sauvagei

1984 ◽  
Vol 246 (5) ◽  
pp. R805-R810 ◽  
Author(s):  
J. W. Campbell ◽  
J. E. Vorhaben ◽  
D. D. Smith
Keyword(s):  
Uric Acid ◽  
Urea Cycle ◽  
Liver Mitochondria ◽  
Synthetase Activity ◽  
Mitochondrial Enzyme ◽  
Ammonia Metabolism ◽  
Carbamoylphosphate Synthetase ◽  
High Degree ◽  
Isolated Liver ◽  
Urea Cycle Enzymes

Glutamine synthetase, a mitochondrial enzyme in liver of uricotelic reptiles and birds, is present in the cytosolic compartment of Phyllomedusa sauvagei liver. The average level is sufficient to account for the rate of uric acid excretion by adult frogs but is far lower than that present in birds and reptiles. Except for lower carbamoylphosphate synthetase activity, the activities of the urea cycle enzymes in P. sauvagei liver are comparable with those in adult ureotelic amphibians. The subcellular distribution of the urea cycle enzymes is much the same as in ureotelic amphibians and mammals with the possible exception of the occurrence of a small percentage of the carbamoylphosphate synthetase and ornithine transacarbamylase activities in the cytosol. In keeping with the subcellular localization of the enzymes, citrulline, and not glutamine, is formed by isolated liver mitochondria. The rapid degradation of glutamine by these mitochondria suggests a high degree of compartmentation of glutamine in the cytosol of P. sauvagei if it is to function as a precursor of uric acid in this compartment.

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