PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Mitochondria, Liver”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed2002

Effects of in vivo treatment of rats with trimethyltin chloride on respiratory properties of rat liver mitochondria.

Liver mitochondria isolated from rats treated in vivo with trimethyltin chloride show stimulation of respiration using glutamate/malate as substrate, and a transient inhibition on rates of respiration using palmitoyl-L-carnitine as substrate. This phenomenon was observed with both ADP- and FCCP-stimulated respiration. In contrast, rates of respiration by liver mitochondria isolated from rats treated in vivo with trimethyltin chloride, following prior treatment with clofibrate, were inhibited when glutamate/malate was respiratory substrates. With palmitoyl-L-carnitine no effect of trimethyltin chloride was observed. In vitro treatment of rat liver mitochondria, or of rat liver homogenates, led to the expected, powerful inhibition of respiration. The synthesis of ATP by liver mitochondria isolated from rats treated in vivo with trimethyltin chloride was not inhibited compared to mitochondria isolated from control rats. Similarly, ATP synthesis by mitochondria isolated from rats treated with clofibrate, before treatment with trimethyltin chloride, was not inhibited. We, therefore, conclude that the powerful inhibitory effects of trimethyltin found in vitro, is not expressed in vivo during the first 36 hr following administration. In vivo treatment of rats with trimethyltin chloride caused a marked increase in hepatic levels of taurine and glycine, while levels of glutathione and glutamine were diminished. This is consistent with an enhanced oxidative stress in the liver. Our findings lead to the conclusion that increased oxidative stress, rather than inhibition of the mitochondrial ATPase, is a likely major cause of the in vivo toxic effects due to trimethyltin chloride.

Adenosine Triphosphate↗
PubMed1975

Effects of vitamin E deficiency on GSH-induced swelling of rat liver mitochondria.

Liver mitochondria from alphatocopherol deficient rats swell more rapidly, both spontaneously and in the presence of GSH, than those from control animals. The increased swelling of deficient mitochondria induced by GSH was completely eliminated when mitochondria were left longer than two hours at 0 degrees in the suspending medium. GSH-induced swelling of liver mitochondria from alpha-tocopherol deficient rats is reversed by ATP, polyvinyl pyrrolidone (PVP) and by oral administration alpha-tocopherol (2 mg/day per rat). Swelling of mitochondria in the above system was completely inhibited by the respiratory chain inhibitor, cyanide (.001 M), and partially by azide (0.001 M). We suggest that the swelling tendency of liver mitochondria from alpha-tocopherol deficient rats might be associated with an altered respiratory mechanism and/or an alteration in membrane permeability.

Adenosine Triphosphate↗
PubMed1981

Phosphoenolpyruvate synthesis by fetal guinea-pig liver mitochondria.

Liver mitochondria isolated from fetal and newborn guinea pigs synthesized phosphoenolpyruvate at 4-6 nmol/min per mg protein with 2 mM malate, succinate, and alpha-ketoglutarate as substrates. These rates were 90-110% of that by adult liver mitochondria and were not substantially altered in the second half of gestation or within 24 h after birth. Both palmitoyl- and octanoylcarnitine were inhibitory to phosphoenolpyruvate synthesis in adult and fetal preparations, but free octanoate was inhibitory only in adult liver mitochondria.

Animals↗
PubMed1984

In vitro effects of microwave radiation on rat liver mitochondria.

Liver mitochondria were exposed in vitro at 30 degrees C to microwave radiation (2.45 GHz) during the following states of respiration: resting, state 1; substrate dependent, state 2; ADP stimulated, state 3; and ADP depleted, state 4. At 10 or 100 mW/g, with succinate as substrate, no effect of exposure was observed on states 1-4 or the respiratory control index (state 3/state 4) of either tightly or loosely coupled mitochondria. When glutamate was used as substrate, no effects were observed at 10 mW/g. However, in the loosely coupled mitochondria the 100 mW/g exposure produced an increase in states 2 and 4 and a decrease in the respiratory control index. The results suggest that the function of loosely coupled mitochondria can be affected at high power levels of microwave radiation.

Animals↗
PubMed1984

Rate control of phosphorylation-coupled respiration by rat liver mitochondria.

Liver mitochondria provided with an oxidizable substrate, ATP, oxygen, and an ADP-generating system (soluble F1-ATPase) were used to reevaluate the rate-controlling step(s) intrinsic to all of the processes of mitochondrial oxidative phosphorylation. The quantity termed "control strength" (C), previously defined as the fractional change in flux through a (system) induced by a fractional change in the concentration of an individual enzyme in the system, has been used to evaluate rate-influencing steps in this overall process by carefully defining the dimensions of the "system" under analysis. If the system is defined by a suspension of mitochondria provided with substrates, plus an extrinsic ADP-generating process (ATPase), the value of C of the latter for the overall process of phosphorylation-linked respiration is near 1.0 until the capacity of the mitochondria to phosphorylate ADP is approached, after which C for the soluble ATPase becomes zero as the maximum capacity for phosphorylation is attained. Carboxyatractyloside was found only marginally to inhibit respiration stimulated by ATPase, even when a large percentage of adenine nucleotide translocase molecules were immobilized. The relative lack of effect of carboxyatractyloside on phosphorylating respiration is explained by the readjustment of the concentration of one of the substrates (ADP) and an inhibitor (ATP), which results from inhibition of adenine nucleotide translocase. The residual blunted inhibition of respiration is explained by product inhibition of the ADP-regenerating ATPase, and not necessarily to any intrinsically mitochondrial intermediate process. The system being evaluated can be redefined to include only the processes intrinsic to mitochondria. This can be achieved by providing exactly comparable substrate concentrations to the mitochondria under comparable incubation conditions. Under these conditions, the adenine nucleotide translocase is the principal, if not the only, rate-controlling step in the overall process of oxidative phosphorylation until a new rate-limitation is attained (ATP synthesis). These data are consistent with the conclusion that, at intermediate rates of phosphorylation-coupled respiration, the extramitochondrial ATP/ADP ratio regulates this process through its kinetic effects on the catalytic properties of the adenine nucleotide translocase.

Adenosine Diphosphate↗
PubMed1996

Effect of polyunsaturated fatty acids deficiency on oxidative phosphorylation in rat liver mitochondria.

Liver mitochondria isolated from controls or polyunsaturated fatty acid (PUFA) deficient rats were studied for oxidative phosphorylation. A PUFA-deficient diet led to a dramatic change in the fatty acid composition of mitochondrial lipid content, similar to that reported in the literature. Besides the changes in lipid composition, mitochondrial volume was enlarged (+45% in state 4 and two-fold in state 3). State 4 respiration was increased together with a decrease in protonmotive force. The non-ohmicity of the relationship between non-phosphorylating respiration and protonmotive force was more pronounced in the PUFA-deficient group. State 3 oxygen consumption as well as the rate of ATP synthesis showed no difference between the two groups, whereas the protonmotive force decreased substantially in mitochondria from PUFA-deficient animals. In contrast, ATP/O ratios were decreased in the PUFA-deficient group when determined at subsaturating ADP concentration. Taken together, these results are in agreement with both an increased non-ohmic proton leak and an increased redox slipping. The relative importance of these two effects on the overall efficiency of oxidative phosphorylation depends on both the rate of oxidative phosphorylation and the maintained protonmotive force. Hence, in isolated mitochondria the respective role of each effect may vary between state 4 and state 3.

Adenosine Triphosphate↗
PubMed1988

Calcium transport and energy coupling in diabetic rat liver mitochondria.

Liver mitochondria from chronic diabetic rats took up Ca ions at a significantly slower rate than their normal counterparts. The same mitochondria, inhibited with ruthenium red, released Ca ions at a faster rate than normal mitochondria. In good agreement with the decrease of Ca ions uptake, measurement of the inner membrane potential by the safranine method yielded a significantly lower value with diabetic than with normal mitochondria. Respiratory control and P/O ratios were also decreased in diabetic mitochondria.

Animals↗
PubMedDate not supplied

Diazepam treatment in rats induces changes in the concentrations of different phospholipid classes in liver and liver mitochondria.

Liver phospholipid concentrations were determined in rats after the administration of diazepam (5 mg/Kg/day), for a period of two months. Increased concentrations of total phospholipids (P < 0.05), phosphatidylcholine (P < 0.05) and phosphatidylinositol (P < 0.05) were found in the rats taking diazepam. In contrast, a decreased concentration of phosphatidylserine (P < 0.01) was observed in the same group of animals. In addition, changes in the concentration of rat liver mitochondrial phospholipids after the administration of diazepam during the same period of time were determined. Increased concentrations of total phospholipids (P < 0.01), phosphatidylcholine (P < 0.001) and diphosphatidylglycerol (P < 0.001) were found in the rats treated with diazepam. In contrast, decreased phosphatidylserine (P < 0.001) and phosphatidylinositol (P < 0.01) concentrations were observed in the same group of animals. The considerable changes observed in liver phospholipids and individual classes of liver mitochondrial phospholipids induced by long-term administration of diazepam, possibly suggest a stimulation of liver phospholipid biosynthesis. This effect may be related to enzymatic systems which are involved in phospholipid pathways, and are linked to benzodiazepinergic binding sites.

Administration, Oral↗
PubMed1978

[Effect of thryoidectomy on the properties of rat liver mitochondria during liver regeneration].

The properties of regenerating rat liver mitochondria are not changed by the thyroidectomy. Thus, hepatectomy induces, in thyroidectomized rats as in normal ones, a decrease in the activity of the outer membrane enzymes, a stimulation of oxidative phosphorylations and an increase of the turn over rate of mitochondrial proteins. Thyroid hormones do not seem to have a major effect upon the liver regeneration mechanism.

Animals↗
PubMed1970

Amino acid incorporation by isolated rat liver mitochondria during liver regeneration.

Intact mitochondria, isolated from regenerating rat liver 2-3 days after partial hepatectomy, are 2.5-3 times more active in amino acid incorporation than mitochondria from control livers. Liver mitochondria from sham-operated animals showed normal amounts of incorporation. Sterile procedures insured low levels of bacterial contamination; cycloheximide was used to eliminate any contribution by contaminating microsomes. Mitochondria from control and 3-day-old regenerating livers were nearly identical in their concentration of several respiratory chain components, P/O ratios, specific O(2) consumption, and cytochrome c oxidase activities. Small differences were observed in respiratory control ratios but these were shown to be unrelated to the differences observed in amino acid incorporating ability. Differential contamination by lysosomes and differences in lysosome fragility were also shown not to be factors in the increased incorporation by regenerating liver mitochondria. Thus, mitochondria from rapidly growing and dividing mammalian tissues are more active in protein synthesis than mitochondria from tissues that grow and divide more slowly.

Adenosine Triphosphate↗
PubMed1990

Lysocardiolipin formation and reacylation in isolated rat liver mitochondria.

Liver mitochondrial cardiolipin (CL) is distinguished from other phospholipids by the presence of linoleoyl in almost all molecular species, and the biosynthesis of these species is not yet understood. The present study was carried out in order to test the hypothesis that the linoleoyl proportion of CL may be specifically enriched by a deacylation-reacylation cycle. Incorporation of [14C]glycerol 3-phosphate into the metabolites of the CL pathway was accompanied by formation of 14C-labelled monolyso- and dilyso-CL. Labelling of dilyso-CL was increased or decreased by stimulation or inhibition respectively of mitochondrial phospholipase A2. These data suggest a rapid deacylation of newly formed [14C]CL by phospholipase A2, whereas endogenous mitochondrial CL was very resistant to hydrolytic degradation. Unlike dilyso-CL, monolyso-CL could be reacylated by [14C]linoleoyl residues. [14C]Linoleoyl incorporation into CL was also observed when exogenous CL was added instead of monolyso-CL, thus indicating the concerted action of de- and re-acylation. Although 1-palmitoyl-2-[14C]linoleoyl-phosphatidylcholine was a suitable acyl donor under experimental conditions, the reaction was not a transacylation but required splitting of [14C]linoleic acid from phosphatidylcholine and formation of [14C]linoleoyl-CoA as an intermediate. The [14C]linoleoyl was mainly bound to the sn-2(2") position of CL, and a small portion (about 20%) to the sn-1(1") position. It is concluded that a cycle, comprising CL deacylation and monolyso-CL reacylation by linoleoyl-CoA, provides a potential mechanism for the remodelling of molecular species of newly formed CL.

Acylation↗
PubMed1969

Oral contraceptives: long-term use produces fine structural changes in liver mitochondria.

Liver biopsies from two groups of women receiving oral contraceptives from 1 to 6 months and from 12 to 30 months, respectively, were examined by electron microscopy. The fine structure of the liver cells from the first group appeared normal, except for an increase in the amount of smooth endoplasmic reticulum. In the second group, however, there were many cases with striking changes-altered shape, increase in size, and presence of paracrystalline inclusions-in the mitochondria. No significant correlation between mitochondrial changes and alterations in liver function was detected.

Adult↗
PubMed1983

Influence of phospholipids on the activity of phosphate-dependent glutaminase in extracts of rat liver mitochondria.

Liver glutaminase can be solubilized from frozen-and-thawed mitochondria by treatment with phospholipase A2. Solubilization by this technique markedly changes the kinetic properties of the enzyme. The properties of the membrane-bound form of the enzyme are partially restored by adding phosphatidylcholine or phosphatidylethanolamine to the phospholipase extract. It is concluded that the kinetic properties of liver glutaminase are a function of the interaction of this enzyme with membrane phospholipids.

Animals↗
PubMed1983

Ketogenesis in mitochondria isolated from liver biopsies of normal and starved dogs: comparison with rat-liver mitochondria.

Fatty acid oxidation and ketogenesis were studied in isolated dog-liver mitochondria in order to investigate whether the absence of hyperketonemia in fasting dogs results from a low capacity of hepatic ketogenesis. Isolated rat-liver mitochondria were used as reference. The results indicate that: (a) Dog-liver mitochondria oxidize long-chain fatty acids and produce ketone bodies at about equal rates as rat-liver mitochondria. No differences were detected in the regulation of ketogenesis. (b) Rates of oxidation of medium-chain fatty acids are significantly lower in dog-liver mitochondria than in rat-liver mitochondria. (c) Fasting does not influence the capacity of liver mitochondria for fatty acid oxidation but their ketogenic capacity is slightly enhanced in both species. The regulation of the energy metabolism in the fasting dog is discussed and compared with that in other mammalian species.

Animals↗
PubMed1992

Ultrastructural aspects and amino acid composition of the purified inner and outer membranes of human liver mitochondria as compared to rat liver mitochondria.

1. The mitochondria isolated from human or rat liver were fractionated into submitochondrial particles and purified inner and outer membrane. According to different marker enzymes the inner membranes were enriched about 5-6-fold and the outer membranes about 12-14-fold. The electron microscopical appearance of the membranes was that expected on the basis of enzymic characterization. 2. A comparison of the average amino acid composition of the membrane proteins from the two types of mitochondria has been made. In the case of submitochondrial particles there were statistically significant differences between the human and rat hydrolysates for only five amino acids. Analysing the purified mitochondrial membranes there were significant differences between the two species for nine amino acids in the case of outer membranes and for 12 amino acids in the case of inner membranes. 3. With one exception all amino acids that were increased or decreased in the outer membrane exhibited a similar trend in the inner membrane of human compared with rat liver mitochondria. It appears that liver mitochondrial membranes have a species-dependent pattern of amino acid composition of their proteins.

Amino Acids↗
PubMedDate not supplied

High phosphate requirement for oxidative phosphorylation and low affinity for phosphate transport in newborn rat liver mitochondria.

Rat liver mitochondria are not fully functional at birth. The relationship between this deficiency and the affinity for phosphate, in oxidative phosphorylation or in phosphate transport, have been studied. The phosphate concentration necessary to observe maximal rate of succinate oxidation in the presence of ADP was higher for newborn than for adult rat liver mitochondria. After preincubation of newborn rat liver mitochondria with ATP, the rate of succinate oxidation in the presence of ADP increased with phosphate concentration similarly for newborn and adult rat liver mitochondria. The maximal rate of phosphate-acetate exchange, which is an indirect measure of the rate of phosphate transport across the mitochondrial membrane, was not significantly different for adult and newborn rat liver mitochondria. On the contrary the apparent affinity for phosphate was about ten-fold lower for newborn than for adult mitochondria.

Adenosine Diphosphate↗
PubMed1985

Stabilising action of carnitine on energy linked processes in rat liver mitochondria.

Rat liver mitochondria exposed to stressing conditions - ageing at room temperature, incubation in the presence of t-butyl hydroperoxide or damaging concentrations of Ca2+ and phosphate- undergo a rapid fall in their membrane potential (delta psi) with a concomitant release of endogenous Mg2+ and accumulated Ca2+. Addition of L-carnitine to the incubation medium considerably delays mitochondrial deenergization. A similar, though lower, protection has also been observed in L-carnitine pretreated and subsequently washed rat liver mitochondria. Furthermore mitochondria isolated from livers of starved rats, treated with L-carnitine 30 minutes before death and exposed to the same stressing conditions show similar delay in the decrease of delta psi and concurrent energy linked processes as compared with untreated animals. Both the in vitro and in vivo results strongly indicate that the stabilising action of L-carnitine on liver mitochondria is due to the removal of membrane bound long chain acyl CoA.

Animals↗