Modification of the rate of oxygen consumption by changes in oxygen concentration in solutions of different osmotic pressure

PROTOPLASMA ◽  
1932 ◽  
Vol 15 (1) ◽  
pp. 629-630
Keyword(s):  
Oxygen Consumption ◽  
Osmotic Pressure ◽  
Oxygen Concentration ◽  
Rate Of Oxygen Consumption

Permeance to oxygen of detached Capsicum annuum fruit

2000 ◽  
Vol 40 (3) ◽  
pp. 457 ◽  
Author(s):  
J. Bower ◽  
B. D. Patterson ◽  
J. J. Jobling
Keyword(s):  
Oxygen Consumption ◽  
Gas Exchange ◽  
Capsicum Annuum ◽  
Oxygen Concentration ◽  
Concentration Gradient ◽  
Gas Diffusion ◽  
Major Barrier ◽  
Capsicum Annuum L ◽  
Rate Of Oxygen Consumption ◽  
Low Rate

The internal oxygen concentration and rate of oxygen consumption of detached capsicum fruits (Capsicum annuum L.) were monitored over several days. From this their overall permeance to oxygen was calculated. When wax was applied to the pedicel and its scar, permeance was reduced by 80–90%, indicating that most gas exchange occurred through this area. Readings from O2 sensors attached to the skins of the fruits were compared to those from O2 sensors inserted into the fruit cavity. These indicated that the cuticle was the major barrier to gas diffusion and that there was a concentration gradient through the capsicum flesh. Permeance of the cuticle was found to be about 0.64 x 10–4 mol O2/Pa.m2.s, while permeance to CO2 was 2–3 times higher. This suggests that the cuticle is composed of a coherent film. The low rate of gas diffusion through capsicum cuticle may allow recycling of respired CO2 by photosynthesis in the flesh before harvest.

scholarly journals THE RESPIRATION OF LUMINOUS BACTERIA AND THE EFFECT OF OXYGEN TENSION UPON OXYGEN CONSUMPTION

1929 ◽  
Vol 13 (1) ◽  
pp. 27-45 ◽  
Author(s):  
Charles S. Shoup
Keyword(s):  
Carbon Dioxide ◽  
Oxygen Consumption ◽  
Oxygen Concentration ◽  
Oxygen Tension ◽  
Small Cells ◽  
Pure Oxygen ◽  
Catalytic Surfaces ◽  
Rate Of Oxygen Consumption ◽  
Luminous Bacteria ◽  
Effect Of Oxygen

1. The respiration of luminous bacteria has been studied by colorimetric and manometric methods. 2. Limulus oxyhaemocyanin has been used as a colorimetric indicator of oxygen consumption and indicator dyes were used for colorimetric determination of carbon dioxide production. 3. The Thunberg-Winterstein microrespirometer has been used for the measurement of the rate of oxygen consumption by luminous bacteria at different partial pressures of oxygen. 4. The effect of oxygen concentration upon oxygen consumption has been followed from equilibrium with air to low pressures of oxygen. 5. Luminous bacteria consume oxygen and produce carbon dioxide independent of oxygen pressures from equilibrium with air (152 mm.) to approximately 22.80 mm. oxygen or 0.03 atmosphere. 6. Dimming of a suspension of luminous bacteria occurs when oxygen tension is lowered to approximately 2 mm. Hg (0.0026 atmosphere) and when the rate of respiration becomes diminished one-half. 7. Pure nitrogen stops respiratory activity and pure oxygen irreversibly inhibits oxygen consumption. 8. The curve for rate of oxygen consumption with oxygen concentration is similar to curves for adsorption of gasses at catalytic surfaces, and agrees with the Langmuir equation for the expression of the amount of gas adsorbed in unimolecular layer at catalytic surfaces with gas pressure. 9. A constant and maximum rate of oxygen consumption occurs in small cells when oxygen concentration becomes sufficient to entirely saturate the surface of the oxidative catalyst of the cell.

Cardiac effects of hypoxia in the neotenous tiger salamanderAmbystoma tigrinum

2002 ◽  
Vol 205 (12) ◽  
pp. 1725-1734 ◽  
Author(s):  
Tom McKean ◽  
Guolian Li ◽  
Kong Wei
Keyword(s):  
Cardiac Output ◽  
Oxygen Consumption ◽  
Oxygen Concentration ◽  
Mechanical Performance ◽  
Cardiac Mass ◽  
Differentially Expressed ◽  
Representational Difference Analysis ◽  
Ambystoma Tigrinum ◽  
Rate Of Oxygen Consumption ◽  
Aquatic Salamanders

SUMMARYThe aquatic form of the tiger salamander Ambystoma tigrinum lives in high-altitude ponds and is exposed to a hypoxic environment that may be either chronic or intermittent. In many animal species, exposure to hypoxia stimulates cardiac output and is followed by an increase in cardiac mass. The working hypothesis of the present study was that the hearts of these aquatic salamanders exposed to 10-14 days of 5 % oxygen in a laboratory setting would become larger and would differentially express proteins that would help confer tolerance to hypoxia. During exposure to hypoxia, cardiac output increased, as did hematocrit. Cardiac mass also increased, but mitotic figures were not detected in the cardiac myocytes of colchicine-injected animals. The mass increase was probably due to hypertrophy, although a very slow rate of hyperplasia cannot be ruled out. Representational difference analysis indicated that at least 14 mRNAs were expressed in hearts from the hypoxic animals that were not expressed in hearts from normoxic animals. The differentially expressed genes were cloned and sequenced and confirmed as coming from the ventricles of the hypoxic salamanders. Genes differentially expressed include mitochondrial genes and genes for elongation factor 2, a protein synthesis gene. The mechanical performance of buffer-perfused hearts isolated from normoxic and hypoxic animals did not differ. Acute responses to hypoxia were also measured. The rate of oxygen consumption of unanesthetized salamanders in metabolism chambers decreased when chamber oxygen concentration was reduced below 12 % oxygen. At a chamber oxygen concentration of 4-6 %, the rate of oxygen consumption of the salamanders was reduced to approximately one-third of the normoxic rate.

Hovering Performance of Hummingbirds in Hyperoxic Gas Mixtures

2001 ◽  
Vol 204 (11) ◽  
pp. 2021-2027 ◽  
Author(s):  
Douglas L. Altshuler ◽  
Peng Chai ◽  
Jeff S. P. Chen
Keyword(s):  
Oxygen Consumption ◽  
Oxygen Concentration ◽  
Atmospheric Oxygen ◽  
Supplemental Oxygen ◽  
Hovering Flight ◽  
Density Reduction ◽  
Air Density ◽  
Reduction Experiment ◽  
Elevational Distribution ◽  
Rate Of Oxygen Consumption

SUMMARY Hummingbirds evolved during a period of decline in atmospheric oxygen concentration and currently encounter varying levels of oxygen availability along their elevational distribution. We tested the hypothesis that inspiration of hyperoxic gas increases hummingbird hovering performance when birds are simultaneously challenged aerodynamically. We measured the maximum duration of hovering flight while simultaneously monitoring the rate of oxygen consumption of ruby-throated hummingbirds (Archilochus colubris) in low-density heliox that was either normoxic (21% O2) or hyperoxic (35% O2). As air density decreased below 0.85kgm−3, hummingbirds hovered significantly longer in hyperoxia than in normoxia, but the air density at which the birds could no longer sustain hovering flight was independent of oxygen concentration. At low air densities in hyperoxia flight trials, hummingbirds appeared to increase their rate of oxygen consumption relative to flight sequences at equivalent densities in normoxia trials, but these differences were not significant. We tested the hypothesis that hummingbirds can discriminate between environments that differ in oxygen concentration. In another density-reduction experiment, hummingbirds were allowed to choose between artificial feeders infused with either normoxic or hyperoxic gases. The hypothesis was not supported because birds failed to associate oxygen concentration with a particular feeder independently of air density. Supplemental oxygen thus yields increased hovering duration at intermediate air densities, but the minimum density at which birds can fly is limited exclusively by aerodynamic considerations.

The Respiration of Pteroides Griseum (Bohadsch) a Pennatulid Coelenterate

1967 ◽  
Vol 46 (1) ◽  
pp. 97-104
Author(s):  
A. E. BRAFIELD ◽  
G. CHAPMAN
Keyword(s):  
Body Weight ◽  
Oxygen Consumption ◽  
Oxygen Concentration ◽  
Continuous Flow ◽  
Strip Chart Recorder ◽  
Total Oxygen ◽  
Strip Chart ◽  
Chart Recorder ◽  
Rate Of Oxygen Consumption ◽  
Exponential Relation

1. The respiration of the pennatulid Pteroides griseum has been investigated by means of a continuous-flow polarographic respirometer and a strip-chart recorder. 2. The rate of oxygen consumption bears the same exponential relation to body weight as in more advanced phyla, and is markedly greater in expanded specimens than in contracted ones. 3. It is suggested that contracted specimens consume oxygen almost exclusively through the ectoderm but that in expanded specimens at least two-thirds of the total oxygen consumed enters through the endoderm. 4. Several sources of evidence confirm that the water within the enteron is poorly oxygenated. Rhythmically fluctuating records of the oxygen concentration of water which has flowed past expanded specimens are the result of periodic expulsions of some of this relatively deoxygenated enteric water. 5. The irrigation of the enteron is very probably brought about by peristaltic waves of contraction which pass along the length of the animal.

Simple Method of Measuring Seston Respiration in Oligotrophic Lakes

1986 ◽  
Vol 43 (8) ◽  
pp. 1660-1663 ◽  
Author(s):  
R. J. Cornett ◽  
F. H. Rigler
Keyword(s):  
Oxygen Consumption ◽  
Oxygen Concentration ◽  
Water Samples ◽  
Simple Technique ◽  
Oxygen Demand ◽  
Simple Method ◽  
Rate Of Oxygen Consumption ◽  
The Difference ◽  
Abiotic Influences ◽  
And Control

A simple technique for measuring the oxygen consumption of seston in oligotrophic waters was developed and tested. Water samples were filtered through 0.45-μm filters. The filters were suspended in biological oxygen demand bottles containing lake water. NaN3 added to one bottle stopped respiration and served as a control to eliminate abiotic influences during the experiments. The difference in oxygen concentration between the respiring and control samples increased linearly over the 1-d experiments. Filtration of hypolimnetic water samples did not significantly alter the rate of oxygen consumption of the seston. Concentrating the seston increased the change in oxygen concentration so that respiration rates from 2 to 80 mg O2∙m−3∙d−1 could be measured. This method is simple, precise, and can measure very low rates of respiration directly.

scholarly journals Recovery heat in muscular contraction without lactic acid formation

1931 ◽  
Vol 108 (757) ◽  
pp. 279-301 ◽  
Keyword(s):  
Acetic Acid ◽  
Oxygen Consumption ◽  
Lactic Acid ◽  
Muscular Contraction ◽  
Acid Formation ◽  
Anaerobic Conditions ◽  
Spontaneous Breakdown ◽  
Rate Of Oxygen Consumption ◽  
Resting Muscle

In a comparison of muscles poisoned with mono-iodo-acetic acid (IAA) in the presence and in the absence of oxygen respectively, Lundsgaard (1930) found:- (1) That the spontaneous breakdown of phosphagen in poisoned resting muscle is much more rapid under anaerobic conditions. (2) That the onset of the characteristic contracture produced by IAA is accompanied always by an increase in the rate of oxygen consumption.

Proximal tubule dysfunction in cystine-loaded tubules: effect of phosphate and metabolic substrates

1996 ◽  
Vol 271 (3) ◽  
pp. F717-F722
Author(s):  
G. Bajaj ◽  
M. Baum
Keyword(s):  
Oxygen Consumption ◽  
Proximal Tubule ◽  
Tricarboxylic Acid Cycle ◽  
Dimethyl Ester ◽  
Proximal Tubules ◽  
Intracellular Atp ◽  
Metabolic Substrates ◽  
Rate Of Oxygen Consumption ◽  
Intracellular Phosphate

Intracellular cystine loading by use of cystine dimethyl ester (CDME) results in a generalized inhibition in proximal tubule transport due, in part, to a decrease in intracellular ATP. The present study examined the importance of phosphate and metabolic substrates in the proximal tubule dysfunction produced by cystine loading. Proximal tubule intracellular phosphorus was 1.8 +/- 0.1 in control tubules and 1.1 +/- 0.1 nmol/mg protein in proximal tubules incubated in vitro with CDME P < 0.001). Infusion of sodium phosphate in rabbits and subsequent incubation of proximal tubules with a high-phosphate medium attenuated the decrease in proximal tubule respiration and prevented the decrease in intracellular ATP with cystine loading. Tricarboxylic acid cycle intermediates have been shown to preserve oxidative metabolism in phosphate-depleted proximal tubules. In proximal tubules incubated with either 1 mM valerate or butyrate, there was a 42 and 34% reduction (both P < 0.05) in the rate of oxygen consumption with cystine loading. However, tubules incubated with 1 mM succinate or citrate had only a 13 and 14% P = NS) reduction in the rate of oxygen consumption, respectively. These data are consistent with a limitation of intracellular phosphate in the pathogenesis of the proximal tubule dysfunction with cystine loading.

Viability and respiratory activity ofPseudomonas syringaecells starved in buffer

1995 ◽  
Vol 41 (4-5) ◽  
pp. 372-377 ◽  
Author(s):  
João P. S. Cabral
Keyword(s):  
Oxygen Consumption ◽  
Electron Transport ◽  
Pseudomonas Syringae ◽  
Respiratory Activity ◽  
Bacterial Cells ◽  
Intact Cells ◽  
Rate Of Oxygen Consumption ◽  
Metabolic Activities ◽  
Different Levels ◽  
Number Of Cells

Pseudomonas syringae cells starved in buffer released orcinol-reactive molecules and materials that absorbed ultraviolet light. The number of cells culturable in nutrient medium decreased more rapidly than the number of intact particles determined by microscopy. The results suggested that starvation resulted in the lysis of an increasing number of cells, and that a fraction of the intact particles were not culturable. Starvation also resulted in a decrease in the rate of oxygen consumption with acetate, glycerol, and succinate, but at different levels. Whereas the respiration of acetate and glycerol decreased concomitantly with culturability, the respiration of succinate decreased to levels similar to the concentration of intact cells, suggesting that all intact particles respired the succinate, but only the culturable cells respired the acetate and glycerol. The results suggest that measuring the activity of the electron-transport system can overestimate the viability of starved bacterial cells, and that complex metabolic activities such as the respiration of acetate and glycerol are probably better suited for the evaluation of this parameter.Key words: Pseudomonas syringae, starvation, culturability, viability, respiration.

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