scholarly journals Human muscle net K+ release during exercise is unaffected by elevated anaerobic metabolism, but reduced after prolonged acclimatization to 4,100 m

2010 ◽  
Vol 299 (1) ◽  
pp. R306-R313 ◽  
Author(s):  
Nikolai B. Nordsborg ◽  
José A. L. Calbet ◽  
Mikael Sander ◽  
Gerrit van Hall ◽  
Carsten Juel ◽  
...  
Keyword(s):  
Exercise Intensity ◽  
Energy Production ◽  
Anaerobic Metabolism ◽  
Hypoxic Exposure ◽  
Bicycle Exercise ◽  
Hypoxic Conditions ◽  
Anaerobic Energy ◽  
K Release ◽  
Bicycle Exercise Test ◽  
Venous Plasma

It was investigated whether skeletal muscle K+ release is linked to the degree of anaerobic energy production. Six subjects performed an incremental bicycle exercise test in normoxic and hypoxic conditions prior to and after 2 and 8 wk of acclimatization to 4,100 m. The highest workload completed by all subjects in all trials was 260 W. With acute hypoxic exposure prior to acclimatization, venous plasma [K+] was lower ( P < 0.05) in normoxia (4.9 ± 0.1 mM) than hypoxia (5.2 ± 0.2 mM) at 260 W, but similar at exhaustion, which occurred at 400 ± 9 W and 307 ± 7 W ( P < 0.05), respectively. At the same absolute exercise intensity, leg net K+ release was unaffected by hypoxic exposure independent of acclimatization. After 8 wk of acclimatization, no difference existed in venous plasma [K+] between the normoxic and hypoxic trial, either at submaximal intensities or at exhaustion (360 ± 14 W vs. 313 ± 8 W; P < 0.05). At the same absolute exercise intensity, leg net K+ release was less ( P < 0.001) than prior to acclimatization and reached negative values in both hypoxic and normoxic conditions after acclimatization. Moreover, the reduction in plasma volume during exercise relative to rest was less ( P < 0.01) in normoxic than hypoxic conditions, irrespective of the degree of acclimatization (at 260 W prior to acclimatization: −4.9 ± 0.8% in normoxia and −10.0 ± 0.4% in hypoxia). It is concluded that leg net K+ release is unrelated to anaerobic energy production and that acclimatization reduces leg net K+ release during exercise.

scholarly journals Metabolism and energetics in squid (Illex illecebrosus, Loligo pealei) during muscular fatigue and recovery

1993 ◽  
Vol 265 (1) ◽  
pp. R157-R165 ◽  
Author(s):  
H. O. Portner ◽  
D. M. Webber ◽  
R. K. O'Dor ◽  
R. G. Boutilier
Keyword(s):  
Energy Production ◽  
Detrimental Effect ◽  
Anaerobic Metabolism ◽  
Energy Status ◽  
Acid Base ◽  
Mantle Tissue ◽  
Anaerobic Energy ◽  
Acid Base Status ◽  
Postexercise Recovery ◽  
Loligo Pealei

The concentrations of intermediate and end products of anaerobic energy metabolism and of free amino acids were determined in mantle musculature and blood sampled from cannulated, unrestrained squid (Loligo pealei, Illex illecebrosus) under control conditions, after fatigue from increasing levels of exercise, and during postexercise recovery. Phosphagen depletion, accumulation of octopine (more so in Illex than in Loligo), and accumulation of succinate indicate that anaerobic metabolism contributes to energy production before fatigue. Proline was a substrate of metabolism in Loligo, as indicated by its depletion in the mantle. In both species, there was no evidence of catabolism of ATP beyond AMP. A comparison of the changes in the free and total levels of adenylates and the phosphagen indicates an earlier detrimental effect of fatigue on the energy status in Loligo. The acidosis provoked by octopine formation in Illex was demonstrated to promote the use of the phosphagen and to protect the free energy change of ATP such that the anaerobic scope of metabolism during swimming is extended and expressed more in Illex than in Loligo. In both species, there was no decrease in the sum of phospho-L-arginine, octopine, and L-arginine, and thus no release of octopine from the mantle, thereby supporting our earlier claim that octopine and associated protons are recycled in the mantle tissue. Overall, the metabolic strategy of Loligo is much less disturbing for the acid-base status. This strategy and the alternative strategy of Illex to keep acidifying protons in the tissue may be important for the protection of hemocyanin function in the two species.

Effects of hypoxic adaptation on myocardial performance and metabolism of Zoarces viviparous

1985 ◽  
Vol 63 (4) ◽  
pp. 821-823 ◽  
Author(s):  
William R. Driedzic ◽  
Hans Gesser ◽  
Kjell Johansen
Keyword(s):  
Energy Production ◽  
Glycolytic Flux ◽  
Adaptation To Hypoxia ◽  
Myocardial Performance ◽  
Tension Development ◽  
Hypoxic Adaptation ◽  
Hypoxic Conditions ◽  
Experimental Fish ◽  
Enzymes Of Energy Metabolism ◽  
Anaerobic Energy

Zoarces viviparous were maintained in either normoxic or hypoxic ([Formula: see text], 4–4.7 kPa) water for 4–6 weeks. The hypothesis that adaptation to hypoxia results in an increase in the potential for anaerobic energy production in heart was tested. There was no difference in the activities of key enzymes of energy metabolism or in the content of myoglobin between the hearts from control or experimental fish. However, ventricular strips from animals adapted to hypoxic conditions were better able to sustain tension development than hearts from control animals during anoxia in the presence of high levels of external Ca2+. A combination of high Ca2+ and glucose was particularly effective in improving performance. The data suggest that hypoxic adaptation leads to an enhancement of Ca2+-activated carbohydrate mobilization but that the enzyme complement required to process the additional glycolytic flux is already in place.

Behavioural responses and biochemical correlates in Solea solea to gradual hypoxic exposure

1998 ◽  
Vol 76 (11) ◽  
pp. 2108-2113 ◽  
Author(s):  
Josef Dalla Via ◽  
Guido Van den Thillart ◽  
Otello Cattani ◽  
Paolo Cortesi
Keyword(s):  
Anaerobic Metabolism ◽  
Oxygen Depletion ◽  
Standard Metabolic Rate ◽  
The Body ◽  
Hypoxic Exposure ◽  
Behavioural Responses ◽  
Hypoxic Conditions ◽  
Solea Solea ◽  
Oxygen Conditions ◽  
Metabolic Strategies

The common sole, Solea solea, a benthic flatfish, is frequently exposed to environmental hypoxic conditions. A succession of behavioural responses to oxygen depletion can be observed. Under moderate hypoxia (80-20% air saturation) the fish reduce spontaneous activity and the scope for activity is lowered. At the onset of anaerobic metabolism (at 20% air saturation) the fish lie still on the bottom, but with increasing severity of hypoxia they start bending the body so as to lift the mouth above the bottom and to reach water layers with higher oxygen concentrations. Between 20 and 6% air saturation, the sole applies two different metabolic strategies: (i) it activates anaerobic metabolism and (ii) it depresses its metabolism below standard metabolic rate. At 5% air saturation or lower the fish swim up with burst- and panic-like movements and lose balance and swim in an uncoordinated manner (below 3%), finally remaining paralysed at the bottom. The correlation of behavioural and metabolic responses clearly shows that under unfavourable oxygen conditions, escape behaviour and burst activity are induced as a last response when other energy-saving alternatives (anaerobic metabolism and metabolic depression) seem to become insufficient.

Squid (Lolliguncula brevis) life in shallow waters: oxygen limitation of metabolism and swimming performance.

1996 ◽  
Vol 199 (4) ◽  
pp. 911-921 ◽  
Author(s):  
E Finke ◽  
H O Pörtner ◽  
P G Lee ◽  
D M Webber
Keyword(s):  
Anaerobic Threshold ◽  
Energy Production ◽  
Anaerobic Metabolism ◽  
Swimming Performance ◽  
Transport Cost ◽  
Energy Requirements ◽  
Swimming Velocity ◽  
Anaerobic Energy ◽  
Mean Pressure ◽  
Lolliguncula Brevis

Squid (Lolliguncula brevis) were exercised in a tunnel respirometer during a stepwise increase in water velocity in order to evaluate the anaerobic threshold, i.e. the critical swimming speed above which anaerobic metabolism contributes to energy production. The average anaerobic threshold was found at speeds of 1.5-2 mantle lengths s-1. Above this velocity, alpha-glycerophosphate, succinate and octopine started to accumulate in the mantle tissue. ATP levels fell and phospho-L-arginine was progressively depleted, while the levels of glucose 6-phosphate and inorganic phosphate rose. The finding of a simultaneous onset of anaerobic metabolism in the cytosol and the mitochondria indicates that a limited oxygen supply to the mitochondria elicits anaerobic energy production. This finding is opposite to the situation found in many other vertebrate and invertebrate species, in which energy requirements in excess of aerobic energy production are covered by anaerobic metabolism, with mitochondria remaining aerobic. In L. brevis, swimming at higher speeds is associated with a small factorial increase in metabolic rate based on a high resting rate of oxygen consumption. Pressure recordings in the mantle cavity support this finding, indicating a high basal level of spontaneous activity at rest and a small rise in mean pressure at higher swimming velocity. Bursts of higher pressures from the jet support elevated swimming speeds and may explain the early transition to anaerobic energy production which occurs when pressure amplitudes exceed 1.2-1.5 kPa or when mean pressure rises above 0.22-0.25 kPa. The finding of mitochondrial hypoxia at a low critical speed in these squid is interpreted to be related to their life in shallow coastal and bay waters, which limits the necessity to maintain high swimming velocities. At increased swimming velocities, the animals oscillate between periods of high and low muscular activity. This behaviour is interpreted to reduce transport cost and to permit a longer-term net use of anaerobic resources when speed exceeds the critical value or when the squid dive into hypoxic waters. The simultaneous onset of anaerobic metabolism in the cytosol and the mitochondria emphasizes that squid generally make maximal use of available oxygen under resting conditions, when their energy requirements are the highest among marine invertebrates.

Conservation of phosphorylation state of cardiac phosphofructokinase during in vitro hypothermic hypoxia

2000 ◽  
Vol 279 (5) ◽  
pp. H2151-H2158 ◽  
Author(s):  
Randy P. Pulis ◽  
Beatrice M. Wu ◽  
Norman M. Kneteman ◽  
Thomas A. Churchill
Keyword(s):  
Posttranslational Modification ◽  
Energy Production ◽  
Anaerobic Metabolism ◽  
Energy Charge ◽  
Metabolic Effects ◽  
Adenylate Energy Charge ◽  
Three Solutions ◽  
University Of Wisconsin ◽  
Anaerobic Energy

We investigated the metabolic effects of buffering agents α-amino-4-imidazole-propionic acid (Histidine), N,N-bis(2-hydroxyethyl)glycine (bicine), N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid (BES) on anaerobic energy production (via glycolysis) and conservation of key regulatory enzyme activity, and phosphofructokinase (PFK) throughout prolonged hypothermic hypoxia in porcine hearts. Hearts from 35 to 40 kg pigs were flushed with one of the following five solutions: St. Thomas' Hospital solution (STHS); modified University of Wisconsin (UW) solution; and three solutions containing modified UW plus 90 mM of histidine, bicine, or BES. The hearts were then stored at 4°C for 10 h. After 10 h of hypothermic hypoxia, lactate values were 6.7–12.9 μmol/g higher than control; this reflected an increase in anaerobic end product of 35–67%. The consequences of enhanced anaerobic metabolism were higher ATP, total adenylate, Energy Charge, and ATP/ADP ratios in most of the buffered groups after 4–10 h cold storage; effectiveness of the buffers employed correlated with buffering capacity (BES proved to be the most effective). PFK remained activated throughout most of the 10-h period in hearts stored with buffers and did not undergo the rapid inactivation experienced by hearts stored in STHS. Conservation of PFK integrity with buffering agents was not related to a pH-mediated event; changes in kinetic parameters suggested that this protection was due to an irreversible posttranslational modification, specifically a dephosphorylation event.

Lactate production in isolated perfused rat lung

1976 ◽  
Vol 231 (2) ◽  
pp. 351-354 ◽  
Author(s):  
WJ Longmore ◽  
JT Mourning
Keyword(s):  
Energy Production ◽  
Glucose Oxidation ◽  
Lactate Production ◽  
High Rate ◽  
Rat Lung ◽  
Aerobic Conditions ◽  
Hypoxic Conditions ◽  
Anaerobic Energy ◽  
Extracellular Lactate ◽  
Perfused Lung

The ability of the isolated perfused rat lung to produce lactate under aerobic and hypoxic conditions has been studied. The lung has been found capable of producing lactate at a rate of 53 mumol/g dry wt per h in the presence of as great as 1 mM extracellular lactate under aerobic conditions. Essentially 100% of the lactate synthesized was derived from [U-14C]glucose. When hypoxic, the rate of lactate production doubled, but only 60% was found to be derived from [U-14C]glucose. When the perfused lung was exposed to aerobic conditions following hypoxia, it was found that lactate production did not decrease. However, lactate production from [U-14C]glucose did increase. It is concluded that lung tissue possesses a high rate of lactate production under aerobic contitions from glucose in comparison to glucose oxidation to CO2. When the lung is hypoxic, lactate production increases as a probable result of amino acid catabolism with little anaerobic energy production occurring. The effect of hypoxia was not reversed within the duration of the performed experiments.

Estimation of anaerobic energy production and efficiency in rats during exercise

1984 ◽  
Vol 56 (2) ◽  
pp. 520-525 ◽  
Author(s):  
G. A. Brooks ◽  
C. M. Donovan ◽  
T. P. White
Keyword(s):  
Total Energy ◽  
Energy Production ◽  
Metabolic Response ◽  
Lactate Production ◽  
Energy Transduction ◽  
Energy Turnover ◽  
External Work ◽  
Gross Efficiency ◽  
Lactate Turnover ◽  
Anaerobic Energy

o assess the effects of gradient and running speed on efficiency of exercise, and to evaluate contributions of oxidative and anaerobic energy production (Ean) during locomotion, two sets of experiments were performed. The caloric expenditures of rats were determined from O2 consumption (VO2) while they ran at three speeds (13.4, 26.8, and 43.1 m/min) on five grades (1, 5, 10, 15, and 20%). In addition, lactate turnover (LaT) and oxidation (Laox) were determined on rats at rest or during running at 13.4 and 26.8 m/min on 1% grade, respectively. Lactate production not represented in the VO2 (i.e., Ean) was calculated from the LaT not accounted for by oxidation [(LaT an) = LaT-Laox)]. The Ean was calculated as: Ean = [LaT an(mumol/min)] [1.38 ATP/La] [11 mcal/mumol ATP]. Gross efficiency of exercise (the caloric equivalent of external work/caloric equivalent of VO2 X 100) ranged from 1.7 to 4.5%. Apparent efficiency (the inverse of the regression of caloric equivalent of VO2 on the caloric equivalent of work X 100) ranged from 20.5 to 26.4% and reflected the metabolic response of rats to applied external work. The contribution of Ean to total energy turnover ranged from 1.6% at rest to 0.8% during running at 13.4 m/min on a 1% grade. Despite active LaT during steady-state exercise, Ean contributes insignificantly to total energy transduction, because over 70% of the lactate produced is removed through oxidation. VO2 adequately represents metabolism under these conditions.

scholarly journals Aerobic and anaerobic metabolism for the zebrafish, Danio rerio, reared under normoxic and hypoxic conditions and exposed to acute hypoxia during development

2010 ◽  
Vol 70 (2) ◽  
pp. 425-434 ◽  
Author(s):  
WR Barrionuevo ◽  
MN Fernandes ◽  
O Rocha
Keyword(s):  
Danio Rerio ◽  
Anaerobic Metabolism ◽  
Developmental Stages ◽  
Acute Hypoxia ◽  
Lactate Concentration ◽  
Growth Delay ◽  
Hypoxic Conditions ◽  
Aerobic And Anaerobic ◽  
Mild Hypoxia

In order to verify the influence of chronic and acute ambient oxygen levels from egg to adult stage of the zebrafish, in vivo oxygen consumption (MO2), critical tensions of oxygen (Pcrit), heart rate (fH) and total body lactate concentration (Lc) were determined for Danio rerio (Hamilton, 1822) raised at 28 °C under normoxic (7.5 mgO2.L-1 or 80 mm.Hg-1) and hypoxic conditions (4.3 mgO2.L-1) and exposed to acute hypoxia during different developmental stages. Our findings confirmed that very early stages do not respond effectively to ambient acute hypoxia. However, after the stage corresponding to the age of 30 days, D. rerio was able to respond to acute hypoxia through effective physiological mechanisms involving aerobic and anaerobic metabolism. Such responses were more efficient for the fishes reared under hypoxia which showed that D. rerio survival capability increased during acclimation to mild hypoxia. Measurements of body mass and length showed that moderate hypoxia did not affect growth significantly until the fish reached the stage of 60 days. Moreover, a growth delay was verified for the hypoxic-reared animals. Also, the D. rerio eggs-to-larvae survival varied from 87.7 to 62.4% in animals reared under normoxia and mild hypoxia, respectively. However, the surviving animals raised under moderated hypoxia showed a better aptitude to regulate aerobic and anaerobic capacities when exposed to acute hypoxia.

Anaerobic metabolism during pubertal development at high altitude

1988 ◽  
Vol 64 (4) ◽  
pp. 1382-1386 ◽  
Author(s):  
N. Fellmann ◽  
M. Bedu ◽  
H. Spielvogel ◽  
G. Falgairette ◽  
E. Van Praagh ◽  
...  
Keyword(s):  
High Altitude ◽  
Anaerobic Metabolism ◽  
Pubertal Development ◽  
Lactate Concentration ◽  
Blood Lactate Concentration ◽  
Bicycle Exercise ◽  
Gonadal Maturation ◽  
Testosterone Concentration ◽  
Salivary Testosterone ◽  
Low Altitude

In a previous study we showed that there were no differences in anaerobic metabolism between groups of 11-yr-old children living at high (3,700 m) and low (330 m) altitudes. The aim of this study is to investigate changes in this metabolism during pubertal development. We compare blood lactate concentration ([L]) after maximal bicycle exercise in 20 boys acclimatized to high altitude (HA, 12 yr old) and at low altitude in 14 boys (LA1, 12 yr old) and in 13 boys (LA2, 14 yr old). The subjects had the same level of physical fitness and the same nutritional and socioeconomic status. Pubertal development was identified by salivary testosterone concentration ([T]). Results (means ± SE) showed 1) at the age of 12 years, [L] and [T] in HA were significantly higher than in LA1 ([L] was 9.2 ± 0.5 vs. 6.8 ± 0.5 mmol/l, [T] was 233 ± 66 vs. 132 ± 30 pmol/l), 2) [L] and [T] in HA were statistically the same as in LA2, and 3) a linear relationship between [L] and [T] was significant (P less than 0.05) in all HA and LA subjects. This suggests that the higher [L] in 12-yr-old boys living at HA could result in an enhanced anaerobic metabolism linked to an earlier gonadal maturation evaluated by testosterone level.

Sign in / Sign up

Export Citation Format

Share Document