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At least 1,279 records · Page 71Linked to original sources
PubMed1991

NADH-dependent respiration in osmotically inactive swollen mitochondria: does transport replace phosphorylation in mediating respiratory control in swollen mitochondria?

Rotenone-sensitive, uncoupler-insensitive, NADH-dependent respiration was demonstrated in osmotically inactive fragments of the mitochondrial inner-membrane obtained following high amplitude (spontaneous) swelling. This NADH-dependent respiration as well as mitochondrial ATPase activity was stimulated by ligands which are known to be transported by specific transporters/mechanisms. The ligands capable of this anomalous respiratory control included several intermediates of the citric acid cycle, besides non-metabolizable ligands including lactate, cations such as K+ and Ca2+. The interaction between NADH-dependent respiration and these ligands, as manifested by stimulation of respiration, was strongly ionic strength-dependent. The thermodynamic relationship between respiratory control and stimulation of transport ATPase by the relevant transportable ligands could also be demonstrated in the conventional (rat liver) microsomes. These experimental results offer a novel experimental base for search into an intra-membranous mechanism of energy transduction.

Animals↗
PubMed1991

Sublethal effects of textile dye stuff effluent on selected oxidative enzymes and tissue respiration of Cyprinus carpio (Linn.).

Toxic effects of sublethal concentration of dye stuff effluent on succinic dehydrogenase (SDH) and lactic dehydrogenase (LDH) activities and tissue respiration were studied in C. carpio. While the sublethal exposure significantly reduced SDH activity and tissue respiration, LDH activity increased in gill, brain, liver, muscle and kidney. The maximum inhibition of SDH activity (74%) was recorded in gill and the minimum (38%) in liver. The percentage reduction of oxygen consumption in the tested tissues was in the order of gill greater than brain greater than liver greater than muscle greater than kidney. The muscle showed the highest level (96%) of increase in LDH activity whereas the kidney cells showed the minimum increase. Exposure to sublethal concentration suppressed the aerobic respiration and triggered the anaerobic respiration.

Animals↗
PubMed1991

[Age-related differences in the effect of osmotic pressure on liver mitochondrial respiration in rats].

The subject under investigation is the influence of osmotic pressure of incubation medium (25-500 mM of sucrose) upon the respiration and the respiration control (RC) of mitochondria of the liver of rats aged 1, 3, 12 and 24 months when oxidizing succinate. In a medium with 0.3 M of sucrose the respiration rate under condition 3 (V3) and RC increased from the age of 1 to 12 months and decreased by 24 months. In a medium with 0.15 M of sucrose the age differences have not been observed. In a uncoupling state the osmotic dependence of the respiration of mitochondria of 1- and 12-month-old rats did not vary. It is assumed that with age there is a change in the rate of structural coupling of the carrier of adenine nucleotides with H(+)-ATP synthetase complex and (or) the viscosity of the matrix.

Aging↗
PubMed1986

[Effect of menadione and vicasol on mitochondrial energy during inhibition of initiation sites of the respiration chain].

Menadione and vicasol completely restore the respiration rate of rat liver mitochondria after its inhibition by rotenone. Under the same conditions these compounds stimulate oxygen consumption by rabbit heart mitochondria up to 40% of the maximal uncoupled respiration rate in the presence of 5 mM glutamate and up to 30% of the maximal uncoupled respiration rate in a lymphocyte suspension containing glucose. Cyanide and dicumarol, specific inhibitors of DT-diaforase, completely suppress the stimulating effect of menadione and vicasol in isolated mitochondria and by 50% in lymphocyte suspensions. The DiS-C3-(5) fluorescence in lymphocyte suspensions suggests that the menadione and vicasol-induced respiration is capable of supporting the mitochondrial transmembrane potential in lymphocytes. Thus, in different tissues menadione and vicasol can restore oxygen consumption in mitochondria, in which the first and second energy coupling sites are inhibited.

Animals↗
PubMed1989

[Phospholipase A activity determines the rate of respiration of the mitochondria in hibernating animals].

The mechanisms for regulating the rate of respiration and oxidative phosphorylation in liver mitochondria from hibernating ground squirrels were studied. The microviscosity of the mitochondrial membrane in hibernating squirrels was found to be higher than that in active animals. Probably, a high microviscosity of the membrane causes a decreases in the rate of the transport of oxidation substrates into the mitochondrial matrix, which in turn may be one of the main reasons for the inhibition of mitochondrial respiration in hibernating squirrels. The activation of phospholipase A2 in a hypotonic medium results in the acceleration of the respiration and phosphorylation in the mitochondria from hibernating squirrels and is accompanied by the increase of the transport of substrates across the mitochondrial membrane. The inhibition of phospholipase A2 decreases Ca2+--induced acceleration of the transport of substrates and prevents the activation of the respiration and phosphorylation in a hypotonic medium.

Animals↗
PubMed1978

Respiration of mammalian cells at low concentrations of oxygen: I. Effect of hypoxic-cell radiosensitizing drugs.

Drugs which sensitize hypoxic mammalian cells to radiation damage in vitro can also affect the cellular respiration rate. This phenomenon was studied in detail to determine whether the changes in oxygen consumption occur at low oxygen concentrations and under optimal nutritional conditions. We have found that cells in tissue culture can undergo adaptive changes in respiration (electron flow) which make them insensitive to the effects of radiosensitizing drugs and even respiration uncouplers such as dinitrophenol, and the inhibitors rotenone and cyanide. At low cell densities, where nutrient depletion in the medium would be negligible, the drugs have reduced effects, particularly at low oxygen concentrations (below 40 mmHg oxygen partial pressure). Parallel cytotoxicity and growht inhibition studies indicate that most drugs are unlikely to have substantial effect on respiration at non-cytotoxic levels.

Cells, Cultured↗
PubMed1988

Control of respiration in non-phosphorylating mitochondria is shared between the proton leak and the respiratory chain.

We measured the relationship between rate of respiration and membrane potential in isolated mitochondria titrated with malonate (to inhibit the electron transport chain) or with uncoupler (to increase the proton conductance of the inner membrane). We used the flux control summation and connectivity theorems of metabolic control theory to calculate the control over non-phosphorylating respiration exerted by the respiratory chain (and associated reactions) and by the leak of protons across the inner membrane. At 37 degrees C the flux control coefficient of the leak over respiration was 0.66; the flux control coefficient of the chain over respiration was 0.34. At 25 degrees C the values were 0.75 and 0.25 respectively. We argue that the basis for previous conclusions that all the control is exerted by the proton leak under similar conditions is invalid.

Animals↗
PubMed1986

[Tissue respiration in chronic bronchitis].

Altogether 445 patients with chronic bronchitis were under observation. Changes in tissue respiration were monitored by shifts in the concentration of pyruvic and lactic acids, LDH and cytochrome c oxidase activity and changes in the concentration of indices of the thiol spectrum. The results obtained showed that chronic bronchitis during exacerbation was characterized by disorders of tissue respiration which did not return to normal even in the course of therapy; aerobic as well as anaerobic oxidation was disturbed. In 91 patients 10-year shifts in indices were detected, however they were less than during exacerbation. Disorders of tissue respiration can be caused by two factors: inflammatory intoxication of organs and tissues and chronic oxygen insufficiency in tissues. Drugs promoting normal tissue respiration are recommended for pathogenetic treatment of chronic bronchitis.

Adult↗
PubMed1988

Changes of alternative respiration during the division cycle of Candida tropicalis.

The changes in cyanide-resistant and SHAM-sensitive respiration have been examined in the cell cycle of yeast cells synchronized by nutrient starvation. The changing of the cyanide-resistant respiration of cells proliferating in synchronizing fermentor, where the glucose concentration was continuously decreasing, was associated with the stage in cell cycle rather than with the alteration of environment. The cyanide-resistant alternative respiration may be attributed characteristic of a certain part of the cell cycle termed "A" phase. This hypothesis is supported by the observation that in cultures proliferating, synchronously under constant conditions, the cyanide-resistant respiration changes periodically and reaches its maximum in the "A" phase after the cell division.

Candida↗
PubMed1988

[Intrauterine growth retardation--CTG findings in pre-partum oxygen respiration and transcutaneous nerve stimulation].

In 33 pregnant women with sonographic diagnosis intrauterine growth retardation (IUGR) 75 O2-mask respirations or, for a comparison, 63 transcutaneous electric paravertebral nerve stimulations (TENS) were carried out between 30 to 39 weeks of gestation. Before, during and after these measures the fetus was monitored by means of continuous CTG-registration. Both in the O2-inhalations and in the TENS the dominant CTG-changes were the rise of the acceleration frequency (in about 41% respectively 49% of the measures) and the increase of the fetal movements (in about 35% respectively 64% of the measures). In the case of some O2-respirations prognostically unfavourable CTG-changes occurred, like fetal tachycardia (in 9 experiments) and firstly occurring decelerations (in 8 experiments), Spikes not being taken into consideration. As those CTG-changes were also seen in some cases with TENS it is concluded that these findings were caused by retardation and that most probably O2-respiration cannot be charged with. Additionally a report is given on nuclearmedical measurements of the uteroplacental blood circulation and on determinations of the concentration of the serumal oxytocinase. The present study shows that by O2-respiration in connection with IUGR obviously no acute risk for the fetus exists which could be proved in the CTG. However it permits no conclusion on the therapeutic effect.

Cardiotocography↗
PubMed1988

Loss of performance while wearing a respirator does not increase during a 22.5-hour wearing period.

To measure loss of performance while wearing a military respirator with and without chemical warfare (CW) clothing for an extended time, a field experiment was carried out with 24 military subjects. With only few short breaks the respirator was worn for 22 h and 30 min, including sleep. Several tests were repeated at different intervals: a 3-km field track run, an obstacle course, and a memory and concentration task. At the field track run the respirator caused 18-20% loss of performance. On the average there was 9% loss of performance at the obstacle course. The memory and concentration task showed 12% loss of performance, however, this only concerned non-mental aspects, such as constriction of visual field. The CW-garment itself led to less loss of performance than the respirator and if both were worn simultaneously, hindrance by the garment was not at all apparent. None of the tests showed an increase in loss of performance with the accumulation of wearing time.

Humans↗
PubMed1988

[Changes in the lipid peroxidation activity and intensity of tissue respiration during healing of aseptic and infected wounds in animal experiments].

The variance of lipid peroxidation (LPO) was studied by the concentrations of malonic dialdehyde (MDA) in the tissue of wound bed and blood serum on the model of surface musculocutaneous aseptic and infected wounds simulated in 250 rats. The speed of oxygen consumption by isolated wound tissue was determined simultaneously. It was stated that the time course of MDA concentration in wounds and sera as well as tissue respiration in animals with infected wounds differed from those in animals with aseptic wounds. In a whole, MDA levels were found to be higher in cases with infected wounds and of changeable character. The latter animals demonstrated less intensive respiration of granulation tissue. Correlation between the variance of tissue respiration and MDA levels was established as was that of LPO and respiration with the phases of wound process. The findings could be used for the development of pathogenetic therapy and evaluation of its efficacy.

Animals↗
PubMed1988

[Biochemical bases of the inhibition and activation of liver mitochondrial respiration in hibernating susliks].

The possible mechanisms in regulation of the respiration rate of mitochondria from liver of hibernating ground squirrels have been investigated. The inhibition of respiration has been shown to be mainly due to the inhibition of electron transfer to the respiratory chain from flavoproteins to cytochrome c. Calcium ions evoke the gradual increase in the respiration rate of mitochondria from liver of hibernating ground squirrels which is abolished by adding albumin, ruthenium red and sovcaine. The lower content of free fatty acids and decreased rate of the oxidation of exogenic NADH in the external pathway indicate the decrease in the activity of phospholipase A2 in mitochondria from liver of hibernating ground squirrels. The decreased calcium capacity of mitochondria indicates the higher sensitivity to calcium ions. A conclusion concerning the leading role of phospholipase A2 in Ca-induced activation of respiration of mitochondria from liver of hibernating ground squirrels is made.

Animals↗
PubMed1987

[Stimulation by quinones of cyanide-resistant respiration in rat liver and heart mitochondria].

It was shown that hydrophilic benzo- and naphthoquinones stimulate the cyanide-resistant respiration in liver and muscle mitochondria when succinate or NADH and glutamate or malate are used as oxidation substrates. The substrate-dependent oxygen uptake in the presence of cyanide is initiated by menadione, vicasol, 1.2-naphthoquinone, coenzyme Q0 and duroquinone. Rotenone and antimycin A do not inhibit the cyanide-resistant respiration. Oxidation of glutamate and malate in the course of CN-resistant respiration is inhibited by ortho- and bathophenanthroline and p-chloromercurybenzoate, whereas succinate oxidation by tenoyltrifluoroacetone, carboxin and pentachlorophenol. Superoxide dismutase, Cu2+ and catalase inhibit the CN-resistant respiration in the presence of quinones. Addition of catalase to the experimental cell causes O2 release.

Animals↗
PubMed1987

[Respiration olfactometry--an objectifying method in the quantitative assessment of hyposmia].

The nasal flow rate is a sensitive parameter for recording respiration reactions evoked by smelling. A method is presented for objectifying measurement of different severe hyposmias. Using the monorhine respiration-olfactometry, one side of the nose is stimulated olfactorily, in the other one the nasal flow rate is registered simultaneously. 22 patients suffering from light and severe hyposmia could be exactly classified corresponding to the severity of hyposmia. There were no smell-induced respiration reactions below the detection threshold. The reaction thresholds of respiration-olfactometry correspond to the detection thresholds of subjective olfactometry in 94% of the patients.

Adolescent↗
PubMedDate not supplied

[Effect of the outer mitochondrial membrane fraction on mitoplast respiration].

Additions of the fraction of outer mitochondrial membranes to the mitoplast suspension is shown to bring about an increase of the ADP-stimulated respiration rate, indices of respiration control and uncoupled respiration. This effect is not a result of the cytochrome c presence in the fraction of outer membranes. In the glycerol-containing medium which causes dissociation of intermembrane contacts the coupling effect of outer membranes on mitoplast respiration is not revealed. It is concluded that the outer membrane in contact with the inner one takes part in realization of the mitochondrial coupling.

Animals↗
PubMed1987

[Effect of rubomycin, carminomycin and adriamycin on respiration in liver mitochondria in various metabolic states, respiratory control and ADP/O ratio].

A comparative study on the effects of antitumour antibiotics of the anthracycline group (rubomycin, carminomycin and adriamycin) on respiration and oxidative phosphorylation in liver mitochondria in various metabolic states has been carried out for the first time. It was shown that the antibiotics under study cause partial inhibition of mitochondrial state 3 respiration, which is eliminated by an uncoupler. Treatment of liver mitochondria with the antibiotics decreases the ADP/O and respiratory control values and stimulates state 4 respiration. The latter is partly inhibited by oligomycin. The uncoupled respiration is decelerated in the presence of the antibiotics. Under these conditions the oxidation of succinate is inhibited by lower concentrations of the antibiotics than that of NAD+-dependent substrates. It was shown that the maximal activity is exerted by the most polar agent carminomycin, while the hydrophobic rubomycin is the least active. The experimental results are discussed in terms of the toxic effect of antitumour antibiotics.

Adenosine Diphosphate↗
PubMed1979

Myocardial respiration and edema following hypothermic cardioplegia and anoxic arrest.

The effects of 1 and 2 hours of hypothermic anoxic arrest and cardioplegia induced by Mg-lidocaine, K-Mg, or K on left ventricular mitochondrial respiratory function, blood flow, and edema were studied in 41 mongrel dogs. Mitochondrial respiration was assessed by the indices of oxidative phosphorylation. Myocardial temperature recorded in ventricular septum was kept at 20 degrees C during ischemic arrest and 10 minutes of reperfusion. Cardioplegic solutions did not influence noncoronary blood flow during cross-clamping of the aorta. Mitochondrial respiratory function remained at control levels after 1 hour of ischemia induced by hypothermic anoxic arrest or by Mg-lidocaine or K-Mg hypothermic cardioplegia. Mitochondrial state 3 respiration after 2 hours of anoxic arrest was significantly higher in Mg-lidocaine cardioplegia than in anoxic arrest (p less than 0.05), but myocardial edema was equivalent in both groups. Mg in the cardioplegic solution suppressed mitochondrial nonphosphorylating oxygen consumption. These data suggest that mitochondrial function after 1 hour of ischemic arrest at 20 degrees C and 10 minutes of reperfusion is not significantly depressed, but at 2 hours of ischemic arrest, mitochondrial respiration is significantly impaired. However, hypothermic Mg-lidocaine cardioplegia appears to be more effective in sustaining myocardial respiration than does simple hypothermic anoxic arrest when the anoxic period is extended to 2 hours.

Animals↗