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PubMed2006

[Effect of plasma membrane ion permeability modulators on respiration and heat output of wheat roots].

A study was made of changes in the rates of respiration, heat production, and membrane characteristics in cells of excised roots of wheat seedlings under the modulation of plasma membrane ion permeability by two membrane active compounds: valinomycin (20 microM (V50)) and chlorpromazine (50 microM (CP50) and 100 microM (CP100)). Both compounds increased the loss of potassium ions, which correlated with the lowering of membrane potential, rate of respiration, and heat production after a 2 h exposure. The differences in alteration of these parameters were due to specific action of either compound on the membrane and to the extent of ion homeostasis disturbance. V20 had a weak effect on the studied parameters. V50 caused an increase of the rate of respiration and heat production, which enhanced following a prolonged action (5 h) and were associated with ion homeostatis restoration. The extent of alteration of membrane characteristics (an increase of potassium loss by roots, and lowering of cell membrane potential) as well as energy expense under the action of CP50 during the first period were more pronounced than in the presence of V50. During a prolonged action of CP50, the increase of respiration intensity and heat production correlated with partial recovery of ion homeostatis in cells. Essential lowering of membrane potential and substantial loss of potassium by cells, starting from the early stages of their response reaction, were followed by inhibition of respiration rate and heat production. Alterations of the structure and functional characteristics of excised root cells indicate the intensification of the membrane-tropic effect of a prolonged action of CP100, and the lack of cell energy resources.

Adaptation, Physiological↗
PubMed1991

Respirability, microstructure and filler content of composite dusts.

Dusts were generated from five composites, with two different shades each. Between 54 and 70 mass percent of the dust (60 to 92% of the particles) collected was respirable. The average particle size collected was 3.97 microns by mass (0.9 microns by number of particles). Between 14 and 22% of the dust generated was respirable. Filler content of the respirable dust particles was within 3 mass percent of the amount of filler in each cured composite. Powder x-ray diffraction revealed that respirable dust particles collected from composites reported to contain crystalline silica fillers contain the same crystalline silica. The results indicate that improperly protected dental personnel who are regularly exposed to composite dusts generated during high-speed finishing of composites containing quartz filler may be at risk for developing silicosis. Dental personnel should wear masks specifically designed to filter respirable silica when finishing composite restorations with high-speed instrumentation.

Air Pollutants, Occupational↗
PubMed1977

[Chacterization of human reticulocytes: respiration, Pasteur effect, and electron microscopic findings on mitochondria].

On 5 blood samples of newborns, whose reticulocytes had been enriched by density gradient centrifugation, and on 25 blood samples of different reticulocytoses of man were determined: the extent of intra- and extramitochondrial respiration, coupling of the electron transfer with the oxidative phosphorylation and the electronmicroscopic appearance, and the number of mitochondria. The reticulocytes occurring in the flowing human blood are in general relatively stiff and are characterized by the following properties:--low respiration--low capacity of the respiratory chain enzymes--weakened Pasteur effect --varying proportion of intramitochondrial respiration and total respiration--decoupling of a major part of the intramitochondrial respiration--low number of mitochondria--qualitative changes of mitochondria. However, there are situations of erythropoiesis where immature reticulocytes are discharged in man (similar to the socalled "stress reticulocytes" of rabbits). On the other hand, it could be shown that the reticulocytes of rabbits are mature in the normal state.

Animals↗
PubMed1990

Submicromolar Ca2+ regulates phosphorylating respiration by normal rat liver and AS-30D hepatoma mitochondria by different mechanisms.

The stimulation of 2-oxoglutarate and NAD(+)-isocitrate dehydrogenase by Ca2+ in mitochondria from normal tissues has been proposed to mediate partially the activation of oxidative energy metabolism elicited by physiological elevations in cytosolic Ca2+. This mode of regulation may also occur in tumor cells in which several aspects of mitochondrial metabolism are known to be altered. This study provides a comparison of the stimulation by submicromolar concentrations of Ca2+ on the rates of ATP-generating (state 3) respiration under physiologically realistic conditions by mitochondria isolated from normal rat liver and from highly malignant rat AS-30D ascites hepatoma cells. The K0.5 for activation of glutamate-dependent state 3 respiration by Ca2+ in the presence of ATP at 37 degrees C was determined to be 0.70 +/- 0.05 (S.E.) microM for hepatoma mitochondria and 0.90 +/- 0.03 microM for rat liver mitochondria. This activation was also reflected by a Ca2(+)-induced shift in the oxidation-reduction state of hepatoma mitochondrial pyridine nucleotides to a more reduced level and Ca2+ stimulation of 14CO2 production from [1-14C]glutamate. Whereas the Ca2+ sensitivity of state 3 respiration by hepatoma mitochondria can be explained by the activation of 2-oxoglutarate and possibly NAD(+)-isocitrate dehydrogenases, the Ca2+ sensitivity of liver mitochondrial respiration appears to be predominantly mediated by activation of electron flow through ubiquinone and Complex III of the electron transport chain, as indicated by the specificity of the effects of Ca2+ on respiration with different oxidizable substrates. Although rat liver and hepatoma mitochondria employ different modes of Ca2(+)-activated ATP generation, these results support the hypothesis that changes in cytosolic Ca2+ play a significant role in the potentiation of energy production in tumor, as well as normal tissue.

Animals↗
PubMedDate not supplied

[Photoinduced inhibition and stimulation of respiration in cells of Halobacterium halobiums kinetics, action spectra, relationship to photoinduction of deltapH].

Along with the inhibition illumination also causes the stimulation of the respiration of H. halobium R1 cells. When light is switched off photoinhibition of respiration (PIR) decays much faster (tau 1/2=12 sec) than photostimulation (PSR) (tau 1/2=60 sec). This allows the evaluation of the contribution of the each phase into the total change of the respiration rate. PIR prevails in neutral and alkaline media (at pH 6.8 the amplitude ratio of PSR/PIR=0.3). At the same conditions light induced alkalization of the medium is observed, which at high light intensities is followed by acidification. The half rise time of PIR is 0.5 divided by 0.8 sec under excitation with short light flashes at 18C and pH 6.8. When pH of the medium is reduced the rate of dark respiration decreases, PSR amplitude increases, PIR is almost not changed and light-induced alkalinization of the medium decreases. At pH 5.5 PSR prevails: at light of 10(5) erg/(cm(2).s) the ratio PSR/PIR=2. The maximum value of PIR and PSR at 18C reaches 20-30 percent of the dark respiration level. Uncouplers (CCCP, DNF) and inhibitor (DCCD) of phosphorylation suppress PIR and light induced alkalinization of the medium and significantly (5-7 times at Ph 6.8) increase PSR and light induced acidification. The action spectra show that bacteriorhodopsin is responsible for all the observed light induced changes of O2 and H+ exchange; carotinoids do not participate in sensibilization. It is suggested that photophosphorylation is necessary for PIR and that PSR is caused by the rise of internal pH due to light induced efflux of protons mediated by bacteriorhodopsin.

Bacteriorhodopsins↗
PubMed1989

A study on the usage of respirators among granite quarry workers in Singapore.

The frequency and correctness of respirators were studied in 5 granite quarries in Singapore involving 201 workers. The overall prevalence of usage of correct respirators was 45.8%. 10.4% of the workers were found to be using the wrong respiratory protective devices. Age, years of exposure and types of occupations were found to affect the usage of respirators. Some common reasons given by workers for not wearing the respirators were 'breathing difficulty', 'hot & sweaty', and 'respirator smells after a while'.

Adult↗
PubMed1989

[Formaldehyde chamber disinfection: not suitable for respirators and anesthesia equipment].

After formaldehyde-chamber-disinfection of respirators considerable quantities of formaldehyde deposit (presumably deep adsorption) within the devices. When the apparatuses are re-employed the respired air contains more than 1,000 (in individual cases more than 4,000) micrograms/m3. Thus all limits are exceeded by far. The liberation of the formaldehyde deposited in considerable amounts comes off according to an exponential equation dependent on the time of employment slowly, that with following chamber disinfections the quantities of formaldehyde in the apparatuses are still increased and still higher loadings of the respired gas occur. Even after employing them for a long time either non-stop or intermittently "saturated" respirators can not be used again. The disinfection according to the principle of the Aseptor-chamber or its imitations has to be refused for respirators and similar medical technical devices, e.g. incubators.

Anesthesia, General↗
PubMed1988

[Relation between respiration and swelling of liver mitochondria induced by anthracycline antibiotics].

The anthracycline antibiotics rubomycin (daunorubicin) and carminomycin at concentrations which stimulate mitochondrial respiration in the absence of ADP induce the swelling of rat liver mitochondria. Under these conditions, the lipid peroxidation (LPO) inhibitor ionol slows down both the respiration and swelling of mitochondria. This suggests that stimulation of respiration and swelling under effects of the antibiotics largely depend on LPO. In the presence of the respiration inhibitor antimycin no effect of ionol is observed. Adriamycin (doxorubicin) stimulates mitochondrial respiration in a lesser degree than rubomycin and carminomycin and fails to induce mitochondrial swelling.

Animals↗
PubMed1988

Neck breathing: a form of voluntary respiration for the spine-injured ventilator-dependent quadriplegic child.

Children with respirator-dependent quadriplegia because of C-2 spinal cord injuries are now surviving the acute stages of their injury. The major cause of mortality and morbidity in the chronic stage is due to respiratory complications. Surveillance, 24 h/d, is the best way to prevent accidental disconnection of respirator equipment from the patient and its inherent catastrophic consequences. The constant risk of disconnection adds tension to the home environment and takes away from the patient any degree of independence or privacy. Because of this, an alternative method of respiration using neck accessory muscles was developed to restore a patient-controlled, voluntary system of respiration. This method, neck breathing, is described in detail in seven children varying in age from 3 years to 16 years 3 months. All seven patients had complete paralysis of the intercostal muscles and the diaphragm. An eighth patient who was unable to learn the technique is also described. Neck breathing is also compared to glossopharygeal breathing, an alternative method of respiration developed during the polio era.

Adolescent↗
PubMed1987

[Therapeutic doses of menadione reduce the rotenone-induced inhibition of respiration and membrane potential generation in mitochondria].

Menadione restores the rotenone-inhibited respiration of diaphragm muscle pieces in approximately the same degree as the respiration of heart mitochondria, i.e., to 30-40%. The respiration of heart mitochondria induced by 2-5 microM menadione (after its inhibition by rotenone) is partly coupled with ATP synthesis whose rate is much lower than that of oxidation of NAD-dependent substrates. The effects of menadione and mitochondrial energetics inhibitors on lymphocyte respiration and rhodamine 123 fluorescence in individual lymphocytes and their suspensions were compared. Menadione (2--5 microM) increased the rotenone + oligomycin suppressed delta psi m in lymphocytes. At 5-40 microM menadione did not act as an uncoupler and had little effect on the uncoupled lymphocyte respiration. All these effects were observed at menadione concentrations close to therapeutic ones. Vicasol, a water-soluble analog of menadione, exerted a similar effect.

Adenosine Triphosphate↗
PubMedDate not supplied

[Effect of corticosterone on mitochondrial respiration of slices of rat liver].

The corticosterone effect on the cyanide-sensitive (mitochondrial) respiration of liver slices of intact and adrenalectomized rats has been studied. The 10(-5) M hormone has been shown to inhibit the mitochondrial respiration of intact rat liver slices. A similar effect is observed in adrenalectomized rats after a short-term stimulation. A stimulating effect of the 10(-8) M steroid on the mitochondrial liver slices respiration is observed in adrenalectomized rats only. Both stimulating and inhibiting effects are recorded 5 min after incubation of the slices with the hormone. It has been concluded that corticosterone can produce a direct effect on the liver cell mitochondrial respiration. It has been assumed that mitochodrial respiration stimulation by a physiological level of the steroid can be important for cell preparation for hormone nucleic effect realization.

Adrenalectomy↗
PubMedDate not supplied

[Phosphorylation and uncoupled respiration in the tissue of rats during the development of homoiothermy].

A marked increase in the rate of mitochondrial respiration, not coupled with ADP phosphorylation, was noted during the transformation of newborn poikilothermic animals into homoeothermic ones in the experiment on the rat tissue homogenates. Uncoupled respiration, as well as coupled one, is realized by the mitochondrial respiration chain, is observed upon oxidation of NADH, succinate, ascorbate and is expressed by a high rate of O2 consumption in the absence of added ADP. During ontogenesis, uncoupled respiration is activated to a greater extent in the heart and skeletal muscle and to a lesser extent in the liver and brown fat. The rates of phosphorylating oxidation of different substrates in tissue homogenates of animals from various age groups differ insignificantly. It is supposed that the postnatal development of homoeothermism in rats is ensured by the formation in many tissues of a system of uncoupled respiration, which takes part in heat production without preliminary ATP synthesis.

Adenosine Diphosphate↗
PubMedDate not supplied

[Effect of limitation of bacterial growth with carbon, sulfur and iron on the synthesis of cytochromes, development of cyanide-resistant respiration and super-synthesis of metabolites].

The work is concerned with the effect produced by limiting the growth of various bacteria with carbon, sulfur and iron on cytochrome synthesis, development of cyanide-resistant respiration and oversynthesis of metabolites. The cessation of bacterial growth due to the exhaustion of a carbon source was shown to be accompanied with the development of cyanide-resistant respiration though the oversynthesis of metabolites did not occur. If the growth was limited by a sulfur or iron source, the concentration of cytochromes a, b and c fell down as compared with that when the growth was limited by a carbon source, and metabolites were produced and accumulated in the medium. In that case, the respiration of virtually all the bacteria was inhibited by cyanide to a great extent. As was demonstrated for Pseudomonas aeruginosa, the development of cyanide-resistant respiration was inhibited when metabolites accumulated and then the respiration became completely resistant to cyanide as soon as the oversynthesis ceased. Apparently, whatever limits the bacterial growth, the process of oversynthesis inhibits cyanide-resistant oxidase.

Bacteriological Techniques↗
PubMedDate not supplied

[Cyanide-resistant respiration of bacteria and its relation to metabolite oversynthesis].

The phenomenon of cyanide-resistant respiration was studied in bacteria as well as its relation to the oversynthesis of metabolites. Cyanide-resistant respiration was shown to be common of aerobic and facultative anaerobic bacteria. The resistance of respiration to cyanide was observed when the growth of a microbial culture was inhibited or ceased entirely, provided the culture lacked the oversynthesis of metabolites. When a culture was capable of metabolites oversynthesis under such conditions, cyanide-resistant respiration (if any) declined. Therefore, there is a competition between metabolites oversynthesis and cyanide-resistant respiration, which is typical of many microorganisms.

Aerobiosis↗
PubMedDate not supplied

[Effect of sulfur, copper, and iron deficiency on the development of cyanide resistant respiration and the cytochrome composition of Pseudomonas aeruginosa].

The effect of deficiency in sulfur, copper and iron in the growth medium on cyanide resistant respiration and cytochrome composition was studied in Pseudomonas aeruginosa and Candida lipolytica. It has been shown that: cyanide resistant respiration was observed at the stationary growth phase when the two microorganisms were cultivated in a complete medium; this respiration was detected already at the phase of decelerated growth in the case of copper deficiency; iron deficiency inhibited cyanide resistant respiration in the bacterium but stimulated its appearance in the yeast; sulfur deficiency inhibited the manifestation of cyanide resistant respiration in the both microorganisms; limitation of the bacterial growth with iron resulted in the accumulation of an iron complex (identical to pyoverdin in its spectral characteristics) in the cultural broth; the deficiency of sulfur, copper and iron inhibited the synthesis of all cytochromes in the bacterium; copper deficiency inhibited only the synthesis of a + a3 in the yeast; iron deficiency inhibited the synthesis of all cytochromes in the yeast; sulfur deficiency had virtually no effect on the content of cytochromes in the yeast. A possible nature of cyanide resistant oxidases in these microorganisms is discussed.

Candida↗
PubMedDate not supplied

[Reduction of respiration and glucose uptake by bacteria after lyophilization].

The techniques of delayed fluorescence and potentiometry were used to study the restoration of respiration and the rate of glucose assimilation by E. coli M-17 rehydrated after lyophilization in various dehydrating media. The activity of respiration and the rate of glucose assimilation decreased after lyophilization, particularly if the cells were freeze-dried without protecting agents. The restoration of respiration and glucose assimilation to the stationary level took 20--60 min after rehydratation. The stationary level was lower than the level of respiration and glucose assimilation before lyophilization. The decrease in respiration and glucose assimilation after lyophilization correlated with the determination of the number of viable cells by the culturing technique only for effective protecting media, viz. sucrose-gelatin and milk. The absence of such a correlation for cells dehydrated in media with low-effective protecting properties is presumed to be due to their synthetic processes being disturbed and genetic damages.

Bacteria↗
PubMed1982

Elevation of the intracellular pH activates respiration and motility of sperm of the sea urchin, Strongylocentrotus purpuratus.

The internal pH (pHi) of sperm of the sea urchin, Strongylocentrotus purpuratus, was estimated by measuring the accumulation of the weak bases [14C]methylamine, [14C]diethylamine, or 9-aminoacridine under conditions where cellular respiration was activated or inhibited. When 9-aminoacridine fluorescence measurements are corrected for binding to intracellular components, the pHi estimates agree quantitatively with those obtained from [14C]amine distributions. The pHi of sperm decreased when the intracellular [K+] was elevated above the physiological value of 10 mM, or when the external pH was substantially decreased below the physiological 8.0, or when Na+ was absent from the seawater. At the decreased pHi values, sperm respiration and motility were inhibited; conversely, both respiration and motility increased when the pHi was elevated. Increased respiration occurred whether the pHi was increased by altering the external pH, [K+] or [Na+], or by the addition of NH4Cl to the medium. In all cases, the activation of respiration and motility were linked, suggesting a unitary control mechanism, some possibilities for which are presented.

Animals↗
PubMedDate not supplied

[Effect of inhibitors of microsomal hydroxylation on endogenous respiration of Torulopsis candida cells].

The effect of inhibitors of microsomal cytochrome P-450 on endogenous respiration and the redox state of components in the electron transport chain was studied in the cells of Torulopsis candida. SKP-525 A and methyrapone in the presence of preliminarily added cyanide (or antimycin A) almost completely inhibited endogenous respiration of the cells irrespective of the growth phase of the culture. The effect of these inhibitors on endogenous respiration and the reduction state of pyridine nucleotides, flavoproteins and cytochromes b, c and a + a3, at all of the studied growth phases, was similar to that of hydroxamic acids, the inhibitors of the mitochondrial alternative oxidase system. Contrary to their action on endogenous respiration of the cells at the exponential phase, both benzhydroxamic acid (BHA) and the inhibitors of microsomal hydroxylation, in the presence of rotenone, suppressed endogenous respiration of the cells taken at the stationary phase. Therefore, the interaction of the electron transport chains changed in the process of the cultural growth. Addition of BHA to the medium inhibited growth of the culture on glucose and biosynthesis of cytochrome P-450 in these cells. The culture did not grow on hexadecane in the presence of BHA. Apparently, hydroxamic acids can affect the operation of the microsomal monooxigenase system containing cytochrome P-450.

Antimycin A↗