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PubMed1980

Action of bacterial lipopolysaccharide on the respiration of mouse liver mitochondria.

Escherichia coli O127:B8 lipopolysaccharide (LPS) inhibited oxygen consumption by isolated mouse liver mitochondria at 10 micrograms of LPS per mg of protein when glutamate + malate was the substrate and adenosine 5'-diphosphate had been added (state 3 respiration), but had little effect when adenosine 5'-diphosphate was not added (state 4 respiration). LPS stimulated state 4 respiration at 10 micrograms/mg of mitochondrial protein when succinate was the substrate but had little effect on state 3 respiration. Lipid A from Shigella sonnei at 2 micrograms/mg of mitochondrial protein also stimulated state 4 respiration but did not affect state 3 respiration with succinate as the substrate. Lipid A, unlike LPS, caused a decrease in the adenosine 5'-diphosphate/O ratio. LPS at 100 micrograms/mg of mitochondrial protein impaired the reduction of cytochromes aa3, c, and b when succinate was the substrate but not when reduced nicotinamide dinucleotide, dithionite, or glutamate was the substrate.

Animals↗

PubMed1981

Influence of oxygen on respiration and glucose catabolism by Treponema pallidum.

Oxygen consumption by Treponema pallidum was observed to be glucose dependent. Treponemes consumed O2 to a low dissolved O2 concentration of 0.01 mumol of O2 per ml when respiration ceased. A fermentative degradation of glucose occurred during the maintenance of treponemes at 0.01 mumol of O2 per ml. Although the initial rate of respiration was independent of the dissolved O2 concentration, the respiration rate decreased upon prolonged incubation at 0.20 mumol of O2 per ml as compared with the respiration rate at 0.7 mumol of O2 per ml. Oxygen was determined to be the major electron acceptor during the oxidative metabolism of glucose. Acetate formation paralleled the respiration rate of the treponemes, whereas lactate production appeared to be independent of respiration. Accumulation of pyruvate occurred at 0.20 mumol of O2 per ml but not at 0.07 mumol/ml. Analyses of enzyme activities in cell-free extracts from treponemes maintained at either 0.07 or 0.20 mumol of O2 per ml for 4 h revealed a loss of pyruvate decarboxylase activity at the higher dissolved O2 concentration, suggesting the inactivation of pyruvate oxidase.

Animals↗

PubMed1971

Cyanide-resistant respiration in Neurospora crassa.

Cell respiration in wild type and poky was studied as part of a long-term investigation of cyanide-resistant respiration in Neurospora. Respiration in wild type proceeds via a cytochrome chain which is similar to that of higher organisms; it is sensitive to antimycin A or cyanide. Poky, on the other hand, respires by means of two alternative oxidase systems. One of these is analogous to the wild-type cytochrome chain in that it can be inhibited by antimycin A or cyanide; this system accounts for as much as 15% of the respiration of poky f(-) and 34% of the respiration of poky f(+). The second oxidase system is unaffected by antimycin A or cyanide at concentrations which inhibit the cytochrome chain maximally. It can, however, be specifically inhibited by salicyl hydroxamic acid. The cyanide-resistant oxidase is not exclusive to poky, but is also present in small quantities in wild type grown under ordinary circumstances. These quantities may be greatly increased (as much as 20-fold) by growing wild type in the presence of antimycin A, cyanide, or chloramphenicol.

Aerobiosis↗

PubMed1973

Respiration of Bdellovibrio bacteriovorus strain 109J and its energy substrates for intraperiplasmic growth.

Measurements of oxidation rates, respiratory quotients (RQ), and release of (14)CO(2) from uniformly labeled substrates showed that glutamate, alpha-ketoglutarate, and synthetic and natural amino acid mixtures are oxidized by suspensions of Bdellovibrio bacteriovorus strain 109J. The oxidation of these substrates largely suppress the endogenous respiration of the Bdellovibrio cells and may or may not cause a small increase, 20 to 50%, in their rate of oxygen consumption. The failure of respired substrates to increase markedly the respiration rate of the Bdellovibrio cells over the endogenous value is discussed. Carbon from these substrates is incorporated into the Bdellovibrio cells during oxidation. Acetate is also oxidized, but its oxidation inhibits endogenous respiration by only about 40% and no acetate is assimilated. The RQ of the Bdellovibrio cells changes from a value characteristic of endogenous respiration to that characteristic of the oxidation of glutamate or of a balanced amino mixture very shortly after the attack of the Bdellovibrio cells on their prey, and the latter RQ is maintained during intraperiplasmic growth. Glutamate, or a mixture of amino acids in the external environment, contributes to the carbon dioxide produced by the Bdellovibrio cells growing intraperiplasmically. It is concluded from these data that amino acids, derived from the breakdown of the protein of the prey, serve as a major energy source during intraperiplasmic growth of B. bacteriovorus 108J. Insofar as they were tested, B. bacteriovorus strains 109D and A. 3. 12 were similar in respiration to strain 109J.

Acetates↗

PubMed1962

Endogenous respiration of Staphylococcus aureus.

Ramsey, H. H. (Stanford University, Palo Alto, Calif.). Endogenous respiration of Staphylococcus aureus. J. Bacteriol. 83:507-514. 1962.-The endogenous respiration of Staphylococcus aureus is dependent upon the medium used to grow the cell suspension. Within wide ranges, the concentration of glucose in the medium has no effect upon subsequent endogenous respiration of the cells, but the concentration of amino acids in the medium, within certain limits, has a very marked effect. The total carbohydrate content of the cells does not decrease during endogenous respiration. As endogenous respiration proceeds, ammonia appears in the supernatant, and the concentration of glutamic acid in the free amino acid pool decreases. Organisms grown in the presence of labeled glutamic acid liberate labeled CO(2) when allowed to respire without added substrate. The principal source of this CO(2) is the free glutamate in the metabolic pool; its liberation is not suppressed by exogenous glucose or glutamate. With totally labeled cells, the free pool undergoes a rapid, but not total, depletion and remains at a low level for a long time. Activity of the protein fraction declines with time and shows the largest net decrease of all fractions. Exogenous glucose does not inhibit the release of labeled CO(2) by totally labeled cells. Other amino acids in the free pool which can serve as endogenous substrates are aspartic acid and, to much lesser extents, glycine and alanine. The results indicate that both free amino acids and cellular protein may serve as endogenous substrates of S. aureus.

Alanine↗

PubMed1997

Premature 3'-end formation of CBP1 mRNA results in the downregulation of cytochrome b mRNA during the induction of respiration in Saccharomyces cerevisiae.

The yeast mitochondrial genome encodes only seven major components of the respiratory chain and ATP synthase; more than 200 other mitochondrial proteins are encoded by nuclear genes. Thus, assembly of functional mitochondria requires coordinate expression of nuclear and mitochondrial genes. One example of coordinate regulation is the stabilization of mitochondrial COB (cytochrome b) mRNA by Cbp1, the product of the nuclear gene CBP1 (cytochrome b processing). CBP1 produces two types of transcripts with different 3' ends: full-length 2.2-kb transcripts and 1.2-kb transcripts truncated within the coding sequence of Cbp1. Upon induction of respiration, the steady-state level of the long transcripts decreases while that of the short transcripts increases reciprocally, an unexpected result since the product of the long transcripts is required for COB mRNA stability and thus for respiration. Here we have tested the hypothesis that the short transcripts, or proteins translated from the short transcripts, are also required for respiration. A protein translated from the short transcripts was not detected by Western analysis, although polysome gradient fractions were shown to contain both long and short CBP1 transcripts. A mutant strain in which production of the short transcripts was abolished showed wild-type growth properties, indicating that the short transcripts are not required for respiration. Due to mutation of the carbon source-responsive element, the long transcript level in the mutant strain did not decrease during induction of respiration. The mutant strain had increased levels of COB RNA, suggestive that production of short CBP1 transcripts is a mechanism for downregulation of the levels of long CBP1 transcripts, Cbp1, and COB mRNA during the induction of respiration.

Base Sequence↗

PubMed1976

Respiration rates for determining the effects of urea on the soil-surface organic horizon of a black spruce stand.

The respiration rates of microflora of layers of soil-surface organic horizon of a black spruce (Picea mariana (Mill.) B.S.P.) stand have been studied manometrically under controlled conditions of moisture, temperature, and aeration in the presence of urea and other nitrogen and mineral amendments. L.F., and F2 samples from field plots fertilized with 448 kg N/ha as urea in 1961 had still in 1971 greater respiration rates than similar samples from unfertilized field plots. In lab tests, addition of urea (112, 280, and 448 kg N/ha or 875, 2187, and 3500 ppm N) stimulated the endogenous respiration of each layer. The stimulation was greater when 2187 ppm N was applied and when moisture and temperature of the layers were maintained at 60% water-holding capacity and 20 degrees C during the 42-day incubation period. Addition of Mg, Ca, and K to urea-fertilized layers increased respiration while P and S decreased it. Addition of NH4NO3 and (NH4)2SO4 impaired the endogenous respiration. The endogenous respiration and moisture, temperature, and fertilizer effects decreased in the order L,F1, and F2 layers.

Bacteria↗

PubMed1982

Effects of dantrolene and D2O on K+-stimulated respiration of skeletal muscle.

We have examined the effects of dantrolene and D2O on the K+-stimulated respiration in frog skeletal muscle. The threshold for K+ stimulation was around 10 mM extracellular potassium concentration ([K+]o). A further marked increase in respiration to levels about ten times the resting level was noted when [K+]o was between 15 and 20 mM. The increase was sustained for hours when [K+]o was less than 20 mM; however, with higher concentrations the stimulation consisted of an initial burst followed by a decline. Dantrolene shifted the relationship between [K+]o and peak increase in respiration toward higher [K+]o by about 10 mM; in addition it nearly completely blocked the sustained component of the increase. D2O, nearly abolished the K+-induced respiration. Neither agent shifted the relationship between [K+]o and membrane potential nor abolished the stimulation of respiration caused by caffeine. Dantrolene did not block the stimulation of Na+ efflux caused by 15 mM K+. The results with these agents are consistent with the proposal that K+-stimulated respiration is due to Ca2+ release into the cytoplasm. In addition, they provide evidence that the stimulated rate of Ca2+ release into the cytoplasm can remain at a persistently high level for hours provided [K+]o does not exceed 20 mM. We calculated that the level of this constant Ca2+ release is about 3.4 X 10(16) ions/(s.cm3).

Animals↗

PubMed1983

Control of brown adipose tissue lipolysis and respiration by adenosine.

Adenosine competitively inhibited the stimulatory effects of (-)-isoproterenol on lipolysis and respiration in hamster brown adipocytes. The low value of the apparent ki for respiratory inhibition by adenosine (7 nM) indicated that the nucleoside may control brown adipocyte function under physiological concentrations. Significantly, the dose-response curves for isoproterenol stimulation of lipolysis and respiration were both shifted by adenosine to higher agonist concentrations by the same order of magnitude, providing additional evidence for a tight coupling between lipolysis and respiration. The inhibitory effects of adenosine were rapidly reversed by a) adenosine deaminase, b) agents known to increase intracellular cyclic AMP levels (isoproterenol, isobutylmethylxanthine, dibutyryl cyclic AMP), and c) direct stimulation of respiration with palmitic acid. These results, combined with the fact that adenosine failed to affect respiration evoked either by dibutyryl cyclic AMP or by palmitic acid, strongly indicate that adenosine regulates brown adipose tissue respiration at an early metabolic step of the stimulus-thermogenesis sequence, most probably at the level of the adenylate cyclase complex.

1-Methyl-3-isobutylxanthine↗

PubMed1995

Cyclosporine A decreases rat skeletal muscle mitochondrial respiration in vitro.

Cyclosporine A (CsA) is a potent immunosuppressant used to decrease organ rejection after transplantation surgery. Reported limitations to use of CsA have been hepatotoxicity and nephrotoxicity. Additionally, exercise capacity is much less than expected following transplantation even if arterial oxygen transport capacity is repaired. Purposes of the present study were to determine the effects of CsA on skeletal muscle mitochondrial respiration in vitro and to determine the site of the CsA skeletal muscle mitochondrial lesion. Mitochondria were isolated from rat hind limb muscle homogenates after differential centrifugation. Mitochondrial respiration was determined using a Rank oxygen polarograph at 37 degrees C in a sucrose and mannitol respiration medium. CsA inhibited maximal respiration (ADP stimulated) in the presence of succinate and rotenone by 18.3% and in the presence of malate and pyruvate by 34.7%. CsA decreased the rate of uncoupled respiration (addition of carbonyl cyanide p-trifluoromethozyphenylhydrazone) by 19.6% and 32.0% for succinate and rotenone, or pyruvate plus malate, respectively. No significant effect of CsA on ADP/O for either substrate was observed. We conclude that CsA inhibits maximal coupled and uncoupled skeletal muscle mitochondrial respiration in vitro. Moreover, although the effects of CsA were greater on electron flux through Complex I, mitochondrial lesions caused by CsA were not specific to either Complex I or Complex II of the electron transport chain (ETC). Poor exercise performance despite adequate arterial oxygenation and systemic and regional oxygen deliveries in transplant patients may be attributed, in part, to the effects of immunosuppressive therapy on ETC capacity of skeletal muscle mitochondria.

Animals↗

PubMed1996

Uptake, excretion and respiration of sucrose and amino acids in the pea aphid Acyrthosiphon pisum

Ingestion, excretion and respiration in aphids were studied using artificial diets labelled with radioactive sucrose or amino acids. The rate of ingestion of a 25 % w/v sucrose diet was 12.4 nl mg-1 h-1 and the honeydew excretion rate was 5.3 nl mg-1 h-1, about 43 % of the volume ingested during the same period. The concentration of sugars in the honeydew was equivalent to 0.53 mol l-1 sucrose and 69 % of the sucrose ingested was assimilated. The amino acid concentration of honeydew was 24.6 mmol l-1 and 94 % of the ingested amino acids were assimilated. Respiration was measured by collecting respired 14CO2 using a chamber which allowed the aphids to feed during the experiments on 14C-labelled artificial diets. While feeding on a 25 % w/v sucrose diet, sucrose was respired at the rate of 1.32x10(-6) mmol mg-1 h-1, equivalent to 0.354 µl O2 mg-1 h-1, which was 14.6 % of the rate of ingestion. There was no evidence that reducing the dietary sucrose concentration from 22 to 11 % w/v had any effect on the rate at which sucrose was respired. Amino acids were respired at a rate of 0.14x10(-6) mmol mg-1 h-1, which was 6.4 % of the rate of ingestion. Dietary sucrose was oxidised in preference to amino acids.

Journal Article↗

PubMed1992

The influence of chloro-substituent sites of hexachlorobiphenyl on the respiration of rat liver mitochondria.

The actions of three hexachlorobiphenyls (HCBs) 2,3,4,2',3',4'-, 2,3,4,3',4',5'- and 3,4,5,3',4',5'-HCBs, on the respiration of rat liver mitochondria with succinate as the substrate were compared, and the effect of chloro-substitution sites in HCB on the respiration was examined. 2,3,4,2',3',4'-HCB strongly inhibited both state 3 and 2,4-dinitrophenol (DNP)-stimulated respiration with 50% inhibition dose of 52 and 54 microM for state 3 and DNP-stimulated respiration, respectively. The inhibitory action of 2,3,4,3',4',5'-HCB on both respiration was approximately half as potent as that of 2,3,4,2',3',4'-HCB. On the other hand, 3,4,5,3',4',5'-HCB did not inhibit any respiration at all. These results indicate that both inside (ortho) and outside (meta or para) positions in each phenyl ring of the biphenyl molecule should be replaced with chlorines for HCB to be an effective inhibitor. Either the actual position of chloro-substituent or steric conformation caused by its substitution or both can be considered as factors affecting the inhibition. On the basis of the conformational energy, calculated by AM1 (Austin model 1) method, with increases in chlorine number in ortho position, HCB molecule became angulated. Furthermore, calculated probability of the conformation distribution for HCB indicated that the probability of nonplanarity was higher for effective HCB than for less effective HCB. These structural features suggest the significance of steric conformation as well as chloro-substituent sites in determining the inhibitory ability of HCB.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed2001

Microbial respiration and chemical composition of different sediment fractions in waterbodies of the upper Paraná River floodplain, Brazil.

Four size fractions of the sediment of six environments of the upper Paraná River floodplain were analyzed for carbon, nitrogen, and phosphorus contents and microbial respiration (oxygen consumption). Particle size did not affect nitrogen and phosphorus content or microbial activity, but did affect carbon content (F = 4.274, df = 3; 20, p = 0.020). The carbon concentration of ultra-fine particles was significantly lower than that of other sizes of sediment particles. Microbial respiration values were well predicted by sediment chemical composition, as shown by multiple regression (microbial respiration = -0.39 - 0.210C + 0.108N + 0.796P; F = 7.0495, p = 0.0022). However, phosphorus was the element which best explained the microbial respiration (partial coefficient = 0.796, p = 0.0039, n = 23). Considering that i) phosphorus was the best predictor of microbial respiration; ii) phosphorus is trapped in the series of reservoirs located upstream from the section of the floodplain studied; and iii) microbial respiration is a measure of decomposition rates and nutrient cycling, we hypothesize that the long-term accumulation of litter detritus and reduction of nutrient cycling in environments of the upper Paraná River floodplain are probable impacts of this decrease in phosphorus caused by the upstream reservoirs.

Bacteria↗

PubMed2004

Effects of propionyl-carnitine on mitochondrial respiration and post-ischaemic cardiac function in the ischaemic underperfused diabetic rat heart.

BACKGROUND AND OBJECTIVE: Carnitine and its derivatives, namely propionyl-carnitine (PC), have been shown to protect cardiac metabolism and function in diabetes mellitus and ischaemic heart disease. Since diabetes is associated with abnormalities in mitochondrial metabolism of fuels, we examined the effects of PC on mitochondrial respiration in ischaemic hearts from streptozotocin-diabetic rats. METHODS: Diabetes was induced in Sprague-Dawley rats by an intravenous injection of streptozotocin. Following the diagnosis of diabetes, oral PC treatment was initiated for a period of 6 weeks. After treatment, cardiac function was determined from working hearts perfused under aerobic conditions and in a separate group of hearts subjected to ischaemia and reperfusion. Mitochondrial respiration was determined under aerobic conditions and following low-flow ischaemia. RESULTS: Rates of state 3 mitochondria respiration with pyruvate were significantly lower in diabetic (n = 4) hearts compared with control (n = 6) hearts (80 +/- 5 vs 112 +/- 5 nanoatoms O2/mg protein/min, respectively), but those with palmitoylcarnitine were similar (101 +/- 11 vs 106 +/- 6 nanoatoms O2/mg protein/min). Diabetic rat heart (n = 8) function, expressed as rate pressure product, was also significantly decreased compared with control (n = 8) hearts (21.5 +/- 1.0 vs 29.5 +/- 0.9 beats x mm Hg x 10(-3)/min, respectively). In PC-treated diabetic (n = 6) hearts, state 3 respiration with pyruvate was increased, and a marked improvement in left ventricular function from 21.5 +/- 1.0 to 26.0 +/- 0.6 beats x mm Hg x 10(-3)/min was observed. During low-flow ischaemia, state 3 respiration with pyruvate remained lower in diabetic (n = 5) hearts compared with control (n = 5) hearts (64 +/- 3 vs 46 +/- 5 nanoatoms O2/mg protein/min, respectively). Following treatment with PC (n = 4), however, respiration with this substrate was significantly increased to 57 +/- 4 nanoatoms O2/mg protein/min. PC was also associated with a significant improvement in cardiac function in reperfused diabetic rat (n = 4) hearts (18.4 +/- 0.2 beats x mm Hg x 10(-3)/min). CONCLUSION: Our results showed that PC has a beneficial effect on cardiac function and increases ischaemic tolerance of the diabetic rat heart. This beneficial effect of PC can be explained, in part, as an improvement in mitochondrial metabolism of pyruvate during the actual ischaemic period.

Animals↗

PubMed1995

A questionnaire survey on the use of dust respirators among lead workers in small scale companies.

In order to find out whether dust respirators are properly used among lead workers in small scale manufacturing companies of lead pigments and stabilizers, a questionnaire survey was carried out for 141 lead workers. The questionnaire consisting of 7 items of questions including selection, use, maintenance, storage and instruction of respirators was distributed to all 141 workers. This survey revealed that 22% of the total workers wore unauthorized dust respirators, and that 73% used a knitcover. Instruction by health supervisors of how to use and where to store the respirators was found to be effective for inspection of valve and a proper place to store dust respirator. However, the result that significantly large percentage of workers used the knitcover following the health supervisors' instruction can be taken to indicate that health supervisors should be given more precise information on deteriorated face-sealing of the respirator facepiece with the knitcover.

Chi-Square Distribution↗

PubMed1996

The effect of the lipid peroxidation product 4-hydroxynonenal and of its metabolite 4-hydroxynonenoic acid on respiration of rat kidney cortex mitochondria.

In rat kidney cortex mitochondria, 4-hydroxynonenal inhibits state 3 respiration as well as uncoupled respiration at micromolar concentrations. The inhibition is more distinct for NAD-linked than for FAD-linked respiration. 4-Hydroxynonenal increases the state 4 respiration. It is assumed that 4-hydroxynonenal behaves like a decoupling agent. 4-Hydroxynonenal augments the inhibitory effect of 2,4-dinitrophenol observed at superoptimal concentrations. 4-Hydroxynonenal is metabolised by renal mitochondria, and 4-hydroxynonenoic acid is one of the metabolites generated. This metabolite is without effect on respiration at concentrations up to 50 microM. Therefore, the effect of 4-hydroxynonenal on respiration is not mediated by this fatty acid derivative formed during respiratory measurements.

Aldehydes↗

PubMed1999

Respirator leakage in the pharmaceutical industry of northwest England.

Field qualitative fit tests were conducted at 10 separate companies in the Northwest of England to determine the proportion of leaking respirators in a cross-section of pharmaceutical manufacturing industries. The 3 M FT-10 Qualitative Fit Test Apparatus was used to test a total of 211 half-face particulate respirator wearers. Participants wore their own respirators and were asked to don them as they would normally. In all cases, no specific intervention had occurred prior to testing. Results indicated a failure rate of 69% (of the 211 subjects tested, 145 respirators were leaking). Successful results were not associated with the frequency of use (p = 0.71) or years of experience wearing respirators (p = 0.59). Similarly, successful results were not associated with respirator training in the current job (p = 0.38) or training in previous jobs (p = 0.49). Leakage was not consistent across the 10 companies, with two companies exhibiting a 100% failure rate while another company had 26 successful tests in 50 wearers (52% pass rate). Only 35 of the 211 participants performed a negative pressure test. Of these, 80% successfully passed the test, which was significantly greater than the 22% pass rate among those who had not performed the pressure test (p < 0.001).

Drug Industry↗

PubMed2003

Principles of physiology and respirator performance.

Several respirator performance criteria are set to satisfy the physiological requirements of the worker. In particular, Ve and PFI must be understood and used appropriately in the design process. Filtration principles and the nature of workplace aerosols must also be understood to determine appropriate test conditions for particulate respirator filters. Current filter test criteria assure that significant aerosol penetration will not occur in the workplace. It is unlikely that existing positive-pressure respirators can assure positive pressure in the breathing zone at all times for all wearers. High, unsustainable work rates and activities such as running in place have been shown to cause negative-pressure excursions under laboratory and workplace conditions. Because these excursions are brief and infrequent for today's respirators, both logic and performance measurements indicate they have a negligible effect on exposure. Filters could no doubt be designed to pass extreme test criteria. Similarly, it may be possible to design positive-pressure respirators to maintain positive pressure 100 percent of the time for all users. However, it is likely that cost and size would increase and comfort could decrease. Further, available evidence demonstrates that today's respirators provide their expected level of protection when properly selected, used, and maintained. As such, there is no demonstrated need for radical design changes.

Aerosols↗