Stimulation Of O2 Uptake Research Articles

Effect of Bicarbonate and Oviduct Fluid on Respiration of Spermatozoa

SummaryThe stimulating effect of low levels of bicarbonate on the respiration rate of boar, ram and rabbit spermatozoa was studied using the oxygen electrode. Bicarbonate at levels of 93, 185 and 283 μ/ml was found to stimulate O2 uptake of boar sperm 17, 21 and 29% (P<.01) respectively. With rabbit sperm the increase in O2 uptake was approximately 14% (P<.01) for all levels. Corresponding values for ram spermatozoa were 16, 13 and 13% (P<.01). Without bicarbonate rabbit sperm respired at a rate of 33, boar sperm 19, and ram sperm 30 μl O2/108 cells/hr. These values are higher than those found with manometric techniques. Succinate significantly stimulated ram sperm respiration above bicarbonate controls. Swine and rabbit spermatozoa utilized significantly more oxygen in the presence of bicarbonate than sperm incubated in the presence of succinate. Additions of oviduct secretions from the sow, ewe and rabbit were found to increase O2 uptake by 18, 11 and 12% respectively over the maximum rate obtained with...

LIGHT STIMULATION OF THE RESPIRATORY ACTIVITY OF RHODOSPIRILLUM RUBRUM CHROMATOPHORES.

Abstract Respiratory activity of chromatophores of Rhodospirillum rubrum, as measured by the O2 uptake, was almost doubled by illumination. Succinoxidase activity of chromatophores was inhibited considerably by o-phenanthroline but not inhibited by KCN either in the dark or light. The aerobic oxidation of p-phenylenediamine in the dark was not inhibited by o-phenanthroline but was completely inhibited by KCN, whereas the oxidation in the light was sensitive to o-phenanthroline but insensitive to KCN. o-Phenanthroline also inhibited other CN−-insensitive reactions in chromatophores, such as photooxidation of reduced cytochrome c2 and the dark-anaerobic oxidation of NADH coupled to the reduction of fumarate. Antimycin A did not inhibit the succinoxidase activity in the dark, but significantly inhibited the activity in the light. Succinate-cytochrome c2 reductase activity was sensitive to antimycin A but insensitive to o-phenanthroline, whereas NADH-cytochrome c2 reductase activity was insensitive to antimycin A but sensitive to o-phenanthroline. The terminal oxidation system in chromatophores is discussed with particular reference to the marked stimulation of O2 uptake by illumination.

Studies in vitro on single beating rat-heart cells: IV. The shift from fat to carbohydrate metabolism in culture

1.1. O2 uptake by rat-heart cells decreases with time in culture.2.2. Primary cells have a respiratory quotient of 0.81, which indicates mainly fat metabolism, while cultured cells have a higher respiratory quotient of 0.96, indicating a shift from fat to carbohydrate metabolism.3.3. Both Crabtree and Pasteur effects are established after 1 week in culture, indicating development of a control mechanism centered about glucose metabolism in culture.4.4. Glucose and palmitate stimulate O2 uptake of primary cells but lose their stimulatory abilities when the Crabtree effect appears. Pyruvate stimulates O2 uptake of both primary and cultured cells to the same extent.5.5. Amytal, at a concentration of 1 mM, inhibitsO2 uptake of primary cells and this inhibition increases with time in culture. In primary cells increased inhibition of O2 uptake by Amytal is obtained in the presence of glucose, despite the fact that addition of glucose to non-inhibited cells increase O2 uptake, while addition of palmitate to Amytal-inhibited cells increases O2 uptake.6.6. A possible shift from fat to carbohydrate metabolism in cultured rat-heart cells has been discussed.

Azione Del 2,4- Dinitrofenolo E Della Tensione Di Ossigeno Sull'Attivazione Respiratoria Di Fettine Di Tubero Di Patata

Abstract The effects of oxygen and of dinitrophenol on the respiratory activation of potato tuber slices. — It is well known that thin slices from storage organs show, in the first period following preparation and washing, a transition from a low to a high level of metabolic activity. In the potato tuber discs (and similar materials) this transition is characterized by: a) a several fold increase of oxygen uptake; b) an increase of the capacity of dissimilating to CO2 the carbon 1 of glucose; c) a decrease of the sensibility of oxygen uptake to the uncoupler 2,4 dinitrophenol (DNP); d) an increase of the capacity of ion and sugar uptake; e) the development of marked capacity of protein synthesis; f) and increase of the activity (as determined in homogenates) of several enzymes involved in the directs oxidation of glucose-6-P or — possibly — in the reoxidation of the TPN reduced by the pentose phosphate pathway reactions. The two latter responses appear with some delay respect the activation of oxygen upta...

Über die Bildung von Wasserstoffperoxyd bei der Hemmung der Glykolyse von Ascites-Tumorzellen durch Phenanthrenchinon

Under aerobic conditions hydrogenperoxide is formed in a glycolyzing suspension of Ehrlich-Ascites tumor cells after incubation with phenanthraquinone(9.10). Not glycolyzing tumor cells and also a kidney cell suspension produce very little hydrogenperoxide only. In glycolyzing tumor cells phenanthraquinone(9.10) is reduced rapidly to the corresponding hydroquinone. During the autoxidation of the hydroquinone hydrogenperoxide is formed. A great stimulation of O2-uptake is related with the autoxidation reaction. This stimulation also appears after blocking the respiratory chain by cyanide. The inhibition of tumor cell glycolysis is caused by an inhibition of glycerinaldehydphosphatdehydrogenase and a decrease of the DPN level.

マメの種子胚の呼吸の研究

1. Gas exchange (in a phosphate buffer, pH 6.0, M/30) of intact germ-axes and slices of various parts of cotyledons isolated from soaked seeds of Vigna sesquipedalis were examined. The Qo2 on a dry weight basis and the RQ were found to be 7.8 and 1.0 for germ-axes and 0.52 and 0.81 for intact cotyledons, respectively. The Qo2 of outer part of cotyledons (1.30) was strikingly higher than that of inner part (0.44) and the RQ of the former (0.82) was lower than that of the latter (0.96). 2. Sodium fluoride and monoiodoacetate inhibited gas exchange of germ-axes strongly, but affected little that of inner part of cotyledons.3. Cyanide and azide inhibited O2 uptake of both germ-axes and inner part of cotyledons much strongly. Oxygen uptake of inner part of cotyledons was inhibited by carbon monoxide more considerably than that of germ-axes. The inhibition was completely (in the latter tissues) or almost completely (in the former) removed by light. Partial suppression of O2 uptake of these two tissues was also evoked by the addition of dieca, salicylaldoxime, α, α'-dipyridyl oro-phenanthroline.4. 2, 4-dinitrophenol stimulated O2 uptake little and CO2 output considerably of germ-axes, whereas it stimulated strongly both O2 uptake and CO2 output of inner part of cotyledons. Essentially similar results were obtained with azide. 5. Gas exchange machineries of the germ-axis and the cotyledon tissues were briefly discussed.

The Metabolism of the Sea-Urchin Egg

ABSTRACT The endogenous O2 uptake of sea-urchin egg homogenates (Echinus esculentus) was inhibited by malonate, fluoride, iodoacetate, and fluoracetate. The addition of the tricarboxylic acid cycle intermediates, citrate, a-keto-glutarate, succinate, fumarate, malate, and glutamate stimulated O2 uptake. The efficiency of the pyruvate-oxidizing mechanism varied in different preparations, but in some, added pyruvate was completely oxidized. (1)-(3) strongly suggest the presence of a tricarboxylic acid cycle. Glycogen, glucose and fructose stimulated O2 uptake. The oxidation of fructose was stimulated by DPN and inhibited by fluoride and iodoacetate. Glucose-1-phosphate, glucose-6-phosphate, fructose-6-phosphate and fruc-tose-i :6 diphosphate stimulated O2 uptake. Phosphogluconate also stimulated O2 uptake, which suggests that the enzymes of the hexose monophosphate shunt system may be present. The experiments described in this paper show that the principal pathway by which carbohydrate is broken down is the normal glycolytic one.

The Physiology of Sea-Urchin Spermatozoa

ABSTRACT When a suspension of sea-urchin semen in sea water is diluted, the total O2 consumed and the rate of O2 uptake per spermatozoon are greater than before dilution. This is the Dilution Effect, first described by Gray (1928a). A further investigation of this phenomenon has been made, using the semen of Echinus esculentus. The form of the O2 uptake-time curve of such suspensions varies according to the ratio semen : sea water. In very dense suspensions d⩾5 × 109 sperm/ml.), the apparent low O2 uptake per unit quantity of spermatozoa is mainly due to inadequate O2 saturation of the lower layers of the suspension, in which the spermatozoa are virtually unable to respire. Such suspensions are not suitable for experiments in Warburg or Barcroft manometers. In dense suspensions (4 × 108 &amp;lt; d ⩽ 109 sperm/ml.) the Dilution Effect was observed when sea water was added to the suspension, in such proportions that the sperm density was only reduced by a factor of 1·14. No Dilution Effect occurred when isotonic ‘Analar’ NaCl was added in the same proportions. On the basis of the small dilution involved, and the negative results with ‘Analar’ NaCl, it is concluded that the Dilution Effect is not exclusively due to the sperm having more space to move after dilution and therefore being able to expend more energy. The Dilution Effect occurs when isotonic ‘Analar’ NaCl containing 1 p.p.m. CuCl2 is added to a dense sperm suspension, in the above proportions. Stimulation of O2 uptake is proportional, over certain limits, to the amount of CuCl2 added. Both CuCl, ZnCl2, and to a lesser extent CuSO4, have similar effects. In a particular experiment, egg-water and Cu salts were about equally efficacious in increasing the O2 uptake of a sperm suspension. The characteristic decline in the O2 uptake of dense suspensions can be partly reversed by the addition of Cu salts. In dilute suspensions (d⩽4 × 108 sperm/ml.), there is no Dilution Effect when sea water or CuCl2 are added in the above proportions. On the other hand, the decline in O2 uptake can be partly arrested by the addition of Cu salts. Diethyldithiocarbamate markedly inhibits the O2 uptake of unwashed seaurchin spermatozoa diluted with sea water. The inhibition does not take place in the presence of added CuCl2. Cu may therefore have a catalytic function in the metabolism of sea-urchin semen. The possibility that Cu lack is responsible for the reduced O2 uptake of spermatozoa in dense suspensions is considered.

The metabolism of fertilized and unfertilized sea-urchin eggs; the action of light and carbon monoxide.

ABSTRACT An investigation has been made into the effect of light and carbon monoxide on the respiration of sea-urchin eggs (Psammechinus miliaris), with special reference to unfertilized eggs. The O2 uptake of unfertilized eggs in air is 38% higher in the dark than in light. This inhibitory action of light persists when gas mixtures containing CO and O2 are substituted for air. Fertilized and unfertilized eggs differ in that the former’s respiration is only about 10% inhibited by light. In 80% CO in O2 in the dark, the O2 uptake of unfertilized eggs is 55% higher than in 80% N2 in O2 in the dark. In 95% CO in O2 in the dark, the O2 uptake of unfertilized eggs is only 7% higher than in 95 % N2 in O2 in the dark, showing that at this partial pressure, CO exerts an inhibitory action on respiration. There is no difference between O2 uptake in 80% CO in O2 in light and dark. O2 uptake in 95 % CO in O2 in light is 45 % higher than in this gas mixture in the dark, showing that at this partial pressure of CO, photo-reversal of respiratory inhibition occurs. Results similar to those in 80% CO in O2 were obtained with gas mixtures containing lower partial pressures of CO. Cytochromes a and were identified spectroscopically in unfertilized eggs. It is concluded that respiration is mediated through the cytochrome system before and after fertilization. In theories which postulate that cytochrome is ‘thrown into circulation’ at fertilization, the simultaneous light-inhibition of respiration, stimulation of O2 uptake by CO, and photo-reversible inhibition of O2 uptake by CO have not been taken into consideration.