scholarly journals Effect of atractyloside on glucose and pyruvate metabolism in rat diaphragm muscle

1968 ◽  
Vol 107 (2) ◽  
pp. 305-309 ◽  
Author(s):  
F. Pocchiari ◽  
V. Silano
Keyword(s):  
Oxygen Uptake ◽  
Glycogen Synthesis ◽  
Specific Radioactivity ◽  
Carbon Dioxide Production ◽  
Diaphragm Muscle ◽  
Appreciable Effect ◽  
Rat Diaphragm ◽  
Substrate Level ◽  
Lactate Formation ◽  
Anaerobic Production

1. In the presence of 1·2mm-atractyloside oxygen uptake by rat diaphragm muscle incubated with 5·6mm-glucose decreases, as well as glycogen synthesis and carbon dioxide production. Lactate formation from glucose increases, but that of phosphoglycerate diminishes fivefold. 2. When pyruvate is used as substrate, atractyloside decreases oxygen uptake. 3. The specific radioactivity of the 14CO2 (μmoles of 14CO2/μmole of oxygen), calculated at concentrations of [1−14C]pyruvate between 0·091mm and 91mm, lies between 3·1×10−4 and 5·7×10−1. Atractyloside increases the specific radioactivity of the 14CO2 with the lowest concentrations of substrate and has no effect when the substrate concentration is 91mm. 4. No appreciable effect of atractyloside on the anaerobic production of 14CO2 from [1−14C]pyruvate at various incubation times and various concentrations is found. 5. It is suggested that atractyloside induces anaerobic conditions in the tissue. Further, it produces a rise in the pyruvate concentration and an ATP deficiency in the cell. Consequently it stimulates pyruvate dismutation, and glycolysis, to which phosphorylation is linked at the substrate level.

scholarly journals Influence of some mononucleotides and their corresponding nucleosides on the metabolism of carbohydrates in the isolated rat diaphragm muscle

1965 ◽  
Vol 97 (2) ◽  
pp. 565-568 ◽  
Author(s):  
A Beloff-Chain ◽  
P Betto ◽  
W Bleszynski ◽  
R Catanzaro ◽  
EB Chain ◽  
...  
Keyword(s):  
Glucose Metabolism ◽  
Incubation Period ◽  
Glycogen Synthesis ◽  
Diaphragm Muscle ◽  
Maximum Effect ◽  
Rat Diaphragm ◽  
Oxidation Of Glucose ◽  
Isolated Rat

1. The influence of ATP on glucose metabolism was studied in the isolated rat diaphragm; it was shown that ATP increases the oxidation of glucose and the aerobic conversion of glucose into lactate, whereas it decreases glycogen synthesis. There was no influence of ATP on the anaerobic formation of lactate from glucose. 2. A maximum effect of ATP on the oxidation of glucose (about 160% increase) was obtained in the presence of 10mm-ATP; in the presence of 2mm-ATP the effect was about 65%, and was approximately constant from 10 to 90min. incubation period. 3. In a phosphate-free tris-buffered medium the oxidation of glucose was considerably decreased, but the percentage stimulation by ATP was about the same as in a phosphate-buffered medium. 4. ATP was shown to increase the oxidation of fructose, glucose 6-phosphate, glucose 1-phosphate, fructose 1,6-diphosphate and, to a much smaller extent, pyruvate. 5. ADP stimulated the oxidation of glucose to the same extent as ATP at a concentration of 2mm and the effect with AMP was only slightly less; IMP and adenosine had only a small stimulatory effect at this concentration, whereas inosine had no effect.

scholarly journals ACTION OF INSULIN ON SUGAR PERMEABILITY IN RAT DIAPHRAGM MUSCLE

1959 ◽  
Vol 42 (6) ◽  
pp. 1277-1299 ◽  
Author(s):  
David Norman ◽  
Piergiulio Menozzi ◽  
Doreen Reid ◽  
Gabriel Lester ◽  
Oscar Hechter
Keyword(s):  
Cell Membrane ◽  
Insulin Action ◽  
Glycogen Synthesis ◽  
Total Cell ◽  
Intracellular Water ◽  
The Other ◽  
Diaphragm Muscle ◽  
Rat Diaphragm ◽  
Cell Water

Insulin action upon sugar permeability has been examined in rat diaphragm muscle prepared so that the fibers are either intact or cut. In intact preparations, sucrose and mannitol are largely excluded from the intracellular water while D-galactose, D-xylose, and L-xylose equilibrate in a small fraction of the total cell water; the availability of cell water for D-galactose, D-xylose, and L-xylose is increased by insulin. In cut preparations, in which the cell membrane is not intact, all the sugars studied penetrate into the cell, but intracellular water is not uniformly available for subsequent permeation. Sucrose distributes in a volume of about 40 to 45 per cent of the available cell water; D-xylose, D-galactose, L-xylose, and mannitol are distributed in all or most of the cell water, but these sugars diffuse at different rates. In cut preparations insulin increases the rate of equilibration of D-galactose and D-xylose without significant effect on the other sugars studied; insulin also exerts a "directive" influence on glycogen synthesis from glucose, which cannot be explained solely in terms of accelerated sugar penetration. The significance of these observations in elucidating the locus of insulin action is discussed.

Physiological responses and energy expenditure during competitive fencing

2014 ◽  
Vol 39 (3) ◽  
pp. 324-328 ◽  
Author(s):  
Raffaele Milia ◽  
Silvana Roberto ◽  
Marco Pinna ◽  
Girolamo Palazzolo ◽  
Irene Sanna ◽  
...  
Keyword(s):  
Heart Rate ◽  
Energy Expenditure ◽  
Oxygen Uptake ◽  
Blood Lactate ◽  
Carbon Dioxide Production ◽  
Maximum Value ◽  
Average Group ◽  
Aerobic Energy Metabolism ◽  
Olympic Sport ◽  
Energetic Expenditure

Fencing is an Olympic sport in which athletes fight one against one using bladed weapons. Contests consist of three 3-min bouts, with rest intervals of 1 min between them. No studies investigating oxygen uptake and energetic demand during fencing competitions exist, thus energetic expenditure and demand in this sport remain speculative. The aim of this study was to understand the physiological capacities underlying fencing performance. Aerobic energy expenditure and the recruitment of lactic anaerobic metabolism were determined in 15 athletes (2 females and 13 males) during a simulation of fencing by using a portable gas analyzer (MedGraphics VO2000), which was able to provide data on oxygen uptake, carbon dioxide production and heart rate. Blood lactate was assessed by means of a portable lactate analyzer. Average group energetic expenditure during the simulation was (mean ± SD) 10.24 ± 0.65 kcal·min−1, corresponding to 8.6 ± 0.54 METs. Oxygen uptakeand heart rate were always below the level of anaerobic threshold previously assessed during the preliminary incremental test, while blood lactate reached its maximum value of 6.9 ± 2.1 mmol·L−1 during the final recovery minute between rounds. Present data suggest that physical demand in fencing is moderate for skilled fencers and that both aerobic energy metabolism and anaerobic lactic energy sources are moderately recruited. This should be considered by coaches when preparing training programs for athletes.

Day to day variability in fat oxidation and the effect after only 1 day of change in diet composition

2016 ◽  
Vol 41 (4) ◽  
pp. 397-404 ◽  
Author(s):  
Eva Maria Støa ◽  
Lill-Katrin Nyhus ◽  
Sandra Claveau Børresen ◽  
Caroline Nygaard ◽  
Åse Marie Hovet ◽  
...  
Keyword(s):  
Oxygen Uptake ◽  
Diet Composition ◽  
Lactate Concentration ◽  
Blood Lactate Concentration ◽  
Fat Oxidation ◽  
Carbon Dioxide Production ◽  
Habitual Diet ◽  
Estimate Rate ◽  
Uptake Test ◽  
Test Retest Reliability

Indirect calorimetry is a common and noninvasive method to estimate rate of fat oxidation (FatOx) during exercise, and test–retest reliability should be considered when interpreting results. Diet also has an impact on FatOx. The aim of the present study was to investigate day to day variations in FatOx during moderate exercise given the same diet and 2 different isoenergetic diets. Nine healthy, moderately-trained females participated in the study. They performed 1 maximal oxygen uptake test and 4 FatOx tests. Habitual diets were recorded and repeated to assess day to day variability in FatOx. FatOx was also measured after 1 day of fat-rich (26.8% carbohydrates (CHO), 23.2% protein, 47.1% fat) and 1 day of CHO-rich diet (62.6% CHO, 20.1% protein, 12.4% fat). The reliability test revealed no differences in FatOx, respiratory exchange ratio (RER), oxygen uptake, carbon dioxide production, heart rate, blood lactate concentration, or blood glucose between the 2 habitual diet days. FatOx decreased after the CHO-rich diet compared with the habitual day 2 (from 0.42 ± 0.15 to 0.29 ± 0.13 g·min−1, p < 0.05). No difference was found in FatOx between fat-rich diet and the 2 habitual diet days. FatOx was 31% lower (from 0.42 ± 0.14 to 0.29 ± 0.13 g·min−1, p < 0.01) after the CHO-rich diet compared with the fat-rich diet. Using RER data to measure FatOx is a reliable method as long as the diet is strictly controlled. However, even a 1-day change in macronutrient composition will likely affect the FatOx results.

scholarly journals Corticosteroid effects on isotonic contractile properties of rat diaphragm muscle

1997 ◽  
Vol 83 (4) ◽  
pp. 1062-1067 ◽  
Author(s):  
Roland H. H. Van Balkom ◽  
Wen-Zhi Zhan ◽  
Y. S. Prakash ◽  
P. N. Richard Dekhuijzen ◽  
Gary C. Sieck
Keyword(s):  
Isometric Force ◽  
Contractile Properties ◽  
Diaphragm Muscle ◽  
Peak Power Output ◽  
Rat Diaphragm ◽  
Fiber Morphology ◽  
Shortening Velocity ◽  
Maximum Isometric Force ◽  
Induced Changes ◽  
Isotonic Contractions

Van Balkom, Roland H. H., Wen-Zhi Zhan, Y. S. Prakash, P. N. Richard Dekhuijzen, and Gary C. Sieck. Corticosteroid effects on isotonic contractile properties of rat diaphragm muscle. J. Appl. Physiol. 83(4): 1062–1067, 1997.—The effects of corticosteroids (CS) on diaphragm muscle (Diam) fiber morphology and contractile properties were evaluated in three groups of rats: controls (Ctl), surgical sham and weight-matched controls (Sham), and CS-treated (6 mg ⋅ kg−1 ⋅ day−1prednisolone at 2.5 ml/h for 3 wk). In the CS-treated Diam, there was a selective atrophy of type IIx and IIb fibers, compared with a generalized atrophy of all fibers in the Sham group. Maximum isometric force was reduced by 20% in the CS group compared with both Ctl and Sham. Maximum shortening velocity in the CS Diamwas slowed by ∼20% compared with Ctl and Sham. Peak power output of the CS Diam was only 60% of Ctl and 70% of Sham. Endurance to repeated isotonic contractions improved in the CS-treated Diam compared with Ctl. We conclude that the atrophy of type IIx and IIb fibers in the Diam can only partially account for the CS-induced changes in isotonic contractile properties. Other factors such as reduced myofibrillar density or altered cross-bridge cycling kinetics are also likely to contribute to the effects of CS treatment.

Interstitial space and collagen alterations of the developing rat diaphragm

1993 ◽  
Vol 74 (5) ◽  
pp. 2450-2455 ◽  
Author(s):  
L. E. Gosselin ◽  
D. A. Martinez ◽  
A. C. Vailas ◽  
G. C. Sieck
Keyword(s):  
Postnatal Growth ◽  
Interstitial Space ◽  
Collagen Content ◽  
Diaphragm Muscle ◽  
Adult Males ◽  
Rat Diaphragm ◽  
Collagen Concentration ◽  
Cross Sectional ◽  
Hydroxyproline Concentration ◽  
Total Muscle

The effect of growth on the relative interstitial space [%total cross-sectional area (CSA)] and collagen content of the rat diaphragm muscle was examined at postnatal ages of 0, 7, 14, and 21 days as well as in adult males. The proportion of interstitial space relative to total muscle CSA was determined by computerized image analysis of lectin-stained cross sections of diaphragm muscle. To assess collagen content and extent of collagen maturation (i.e., cross-linking), high-pressure liquid chromatography analysis was used to measure hydroxyproline concentration and the nonreducible collagen cross-link hydroxylysylpyridinoline (HP), respectively. At birth, interstitial space accounted for approximately 47% of total diaphragm muscle CSA. During postnatal growth, the relative contribution of interstitial space decreased such that by adulthood the interstitial space accounted for approximately 18% of total muscle CSA. The change in relative interstitial space occurred without a concomitant change in hydroxyproline concentration. However, the concentration of HP markedly increased with age such that the adult diaphragm contained approximately 17 times more HP than at birth. These results indicate that during development the relative CSA occupied by interstitial space decreases as muscle fiber size increases. However, the reduction in relative interstitial space is not associated with a change in collagen concentration. Thus collagen density in the interstitial space may increase with age. It is possible that the observed changes in relative interstitial space and collagen influence the passive length-force properties of the diaphragm.

scholarly journals Glucose metabolism in the newborn rat. Hormonal effects in vivo

1973 ◽  
Vol 134 (4) ◽  
pp. 899-906 ◽  
Author(s):  
Keith Snell ◽  
Deryck G. Walker
Keyword(s):  
Cyclic Amp ◽  
Intraperitoneal Injection ◽  
Actinomycin D ◽  
Specific Radioactivity ◽  
Liver Glycogen ◽  
Newborn Rats ◽  
Dibutyryl Cyclic Amp ◽  
Lactate Formation ◽  
Glucose Formation

1. The concentrations of liver glycogen and plasma d-glucose were measured in caesarian-delivered newborn rats at time-intervals up to 3h after delivery after treatment of the neonatal rats with glucagon, dibutyryl cyclic AMP, cortisol or cortisol+dibutyryl cyclic AMP. Glycogenolysis was promoted by glucagon or dibutyryl cyclic AMP in the third hour after birth but not at earlier times. Cortisol and dibutyryl cyclic AMP together (but neither agent alone) promoted glycogenolysis in the second hour after birth, but no hormone combination was effective in the first postnatal hour. 2. The specific radioactivity of plasma d-glucose was measured as a function of time for up to 75 min after the intraperitoneal injection of d-[6-14C]glucose and d-[6-3H]glucose into newborn rats at delivery and after treatment with glucagon or actinomycin D. Glucagon-mediated hyperglycaemia at this time was due to an increased rate of glucose formation and a decreased rate of glucose utilization. Actinomycin D prevented glucose formation and accelerated the rate of postnatal hypoglycaemia. 3. The specific radioactivity of plasma l-lactate and the incorporation of 14C into plasma d-glucose was measured as a function of time after the intraperitoneal injection of l-[U-14C]lactate into glucagon- or actinomycin D-treated rats immediately after delivery. The calculated rates of lactate formation were unchanged by either treatment, but lactate utilization was stimulated by glucagon administration. Glucagon stimulated and actinomycin D diminished 14C incorporation into plasma d-glucose. 4. The factors involved in the initiation of glycogenolysis and gluconeogenesis in the rat immediately after birth are discussed.

Intracellular pH transients in rat diaphragm muscle measured with DMO

1978 ◽  
Vol 235 (1) ◽  
pp. C49-C54 ◽  
Author(s):  
A. Roos ◽  
W. F. Boron
Keyword(s):  
Intracellular Ph ◽  
Weak Acid ◽  
Diaphragm Muscle ◽  
Disulfonic Acid ◽  
Free Solution ◽  
Rat Diaphragm ◽  
Control Value ◽  
Acid Load ◽  
Acid Extrusion ◽  
Acid Loading

Changes of the intracellular pH of rat diaphragm muscle were monitored at 30-min intervals with the weak acid DMO (5,5-dimethyl-2,4-oxazolidinedione). Transferring the muscle from a CO2-containing to a CO2-free solution caused intracellular pH (pHi) to rise by an average of 0.18 during the first 30 min and then to level off at a slightly lower value over the next 60-90 min. Transferring the muscle from a CO2-free to a CO2-containing solution caused pHi to fall by 0.18 during the first 30 min and then to recover by 0.05 over the next 90 min. Subsequent return to the CO2-free solution caused pHi to overshoot the control value by 0.10. Both the recovery and the overshoot can be accounted for by an acid-extruding pump. Intracellular acid loading with 118 mM DMO similarly caused pHi to fall initially, to recover slowly during the acid loading, and then to overshoot the control pHi on removal of the acid load. In the absence of HCO3-/CO2, acid extrusion was reduced by about a fifth. SITS (4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid) had no effect. The absence of either Na+ or Cl- from HCO3-/CO2- free solution reduced acid extrusion by about a half.

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