Alactic ATP Turnover Rate during 30-S Cycle Sprints in Females and Males

1994 ◽  
Vol 87 (s1) ◽  
pp. 125-126 ◽  
Author(s):  
K Bodin ◽  
M Esbjörnsson ◽  
E Jansson
Keyword(s):  
Turnover Rate ◽  
Atp Turnover

Muscle ATP turnover rate during isometric contraction in humans

1986 ◽  
Vol 60 (6) ◽  
pp. 1839-1842 ◽  
Author(s):  
A. Katz ◽  
K. Sahlin ◽  
J. Henriksson
Keyword(s):  
Isometric Contraction ◽  
Turnover Rate ◽  
Knee Extensor ◽  
High Energy ◽  
High Energy Phosphates ◽  
Atp Turnover ◽  
Contraction Duration ◽  
Extensor Muscles ◽  
Before And After ◽  
Fast Twitch

ATP turnover and glycolytic rates during isometric contraction in humans have been investigated. Subjects contracted the knee extensor muscles at two-thirds maximal voluntary force to fatigue (mean +/- SE, 53 +/- 4 s). Biopsies were obtained before and after exercise and analyzed for high-energy phosphates and glycogenolytic-glycolytic intermediates. Total ATP turnover was 190 +/- 7 mmol/kg dry muscle, whereas the average turnover rate was 3.7 +/- 0.2 mmol . kg dry muscle-1 . S-1. The average ATP turnover rate was positively correlated with the percentage of fast-twitch fibers in the postexercise biopsy (r = 0.71; P less than 0.05) and negatively correlated with contraction duration to fatigue (r = -0.88; P less than 0.05). At fatigue, phosphocreatine ranged from 1 to 11 mmol/kg dry muscle (86–99% depletion of value at rest), whereas lactate ranged from 59 to 101. The mean glycolytic rate was 0.83 +/- 0.05 mmol . kg dry muscle-1 . S-1 and was positively correlated with the rate of glucose 6-phosphate accumulation (r = 0.83; P less than 0.05). It is concluded that a major determinant of the ATP turnover rate is the muscle fiber composition, which is probably explained by a higher turnover rate in fast-twitch fibers; fatigue is more closely related to a low phosphocreatine content than to a high lactate content; and the increase in prephosphofructokinase intermediates is important for stimulating glycolysis during contraction.

scholarly journals Myosin ATP Turnover Rate: A Mechanism Involved in Thermogenesis in Resting Skeletal Muscle Fibers

2010 ◽  
Vol 98 (3) ◽  
pp. 145a
Author(s):  
Melanie Stewart ◽  
Kathleen Franks-Skiba ◽  
Roger Cooke
Keyword(s):  
Skeletal Muscle ◽  
Turnover Rate ◽  
Muscle Fibers ◽  
Atp Turnover ◽  
Skeletal Muscle Fibers

Halothane and the Beating Response and ATP Turnover Rate of Heart Cells in Tissue Culture

1975 ◽  
Vol 42 (2) ◽  
pp. 123-132 ◽  
Author(s):  
Linda J. Stong ◽  
Charles R. Hartzell ◽  
Richard L. McCarl
Keyword(s):  
Tissue Culture ◽  
Turnover Rate ◽  
Heart Cells ◽  
Atp Turnover

Muscle ammonia metabolism during isometric contraction in humans

1986 ◽  
Vol 250 (6) ◽  
pp. C834-C840 ◽  
Author(s):  
A. Katz ◽  
K. Sahlin ◽  
J. Henriksson
Keyword(s):  
Turnover Rate ◽  
Adenine Nucleotide ◽  
Isometric Exercise ◽  
Voluntary Contraction ◽  
Minor Importance ◽  
Amp Deaminase ◽  
Muscle Lactate ◽  
Ammonia Metabolism ◽  
Atp Turnover

The changes in ammonia (NH3) and amino acid contents in human skeletal muscle during isometric exercise (2/3 maximal voluntary contraction force) to fatigue have been investigated. Biopsies from musculus quadriceps femoris were obtained at rest, fatigue, and 1 and 4 min recovery. Muscle NH3 (n = 9) increased from 1.3 +/- 0.3 (mean +/- SE) mmol/kg dry muscle (dm) at rest to 3.6 +/- 0.6 at fatigue (P less than 0.01) and remained elevated during recovery, whereas the lactate increase after contraction decreased rapidly during recovery. Total adenine nucleotide (TAN) content decreased from 28.7 +/- 0.5 mmol/kg dm at rest to 25.1 +/- 0.6 at fatigue (P less than 0.001). Muscle glutamine did not change after contraction (P greater than 0.05), whereas glutamate decreased (P less than 0.001), and alanine increased (P less than 0.001). In vivo AMP deaminase activity (measured by the rate of TAN decrease) was positively correlated with the percentage of fast-twitch fibers (r = 0.92; P less than 0.001) and the ATP turnover rate (r = 0.75; P less than 0.001) but was not related to the muscle lactate content (r = 0.27; P greater than 0.05). Phosphocreatine decreased to 6.1 +/- 0.7 mmol/kg dm (range = 1-11) after contraction. It is concluded that during exercise activation of AMP deaminase in vivo occurs when a high ATP turnover rate is coupled with a low phosphocreatine level, muscle pH is of minor importance for direct activation of AMP deaminase in vivo, and increases in NH3 do not have an important influence on glycolysis.

scholarly journals O2-sensing signal cascade: clamping of O2 respiration, reduced ATP utilization, and inducible fumarate respiration

2008 ◽  
Vol 295 (1) ◽  
pp. C29-C37 ◽  
Author(s):  
Vijayalakshmi Sridharan ◽  
Jason Guichard ◽  
Chuan-Yuan Li ◽  
Robin Muise-Helmericks ◽  
Craig Cano Beeson ◽  
...  
Keyword(s):  
Turnover Rate ◽  
Lactic Acid Production ◽  
Hypoxia Inducible Factor ◽  
Terminal Electron Acceptor ◽  
Neonatal Cardiomyocytes ◽  
Atp Turnover ◽  
Transport Chain ◽  
Pathway Activation ◽  
Atp Generation ◽  
Purine Nucleotide Cycle

These studies explore the consequences of activating the prolyl hydroxylase (PHD) O2-sensing pathway in spontaneously twitching neonatal cardiomyocytes. Full activation of the PHD pathway was achieved using the broad-spectrum PHD inhibitor (PHI) dimethyloxaloylglycine (DMOG). PHI treatment of cardiomyocytes caused an 85% decrease in O2 consumption and a 300% increase in lactic acid production under basal conditions. This indicates a ∼75% decrease in ATP turnover rate, inasmuch as the increased ATP generation by glycolysis is inadequate to compensate for the lower respiration. To determine the extent to which decreased ATP turnover underlies the suppressed O2 consumption, mitochondria were uncoupled with 2,4-dinitrophenol. We were surprised to find that 2,4-dinitrophenol failed to increase O2 consumption by PHI-treated cells, indicating that electron transport chain activity, rather than ATP turnover rate, limits respiration in PHI-treated cardiomyocytes. Silencing of hypoxia-inducible factor-1α (HIF-1α) expression restored the ability of uncoupled PHI-treated myocytes to increase O2 consumption; however, basal O2 uptake rates remained low because of the unabated suppression of cellular ATP consumption. Thus it appears that respiration is actively “clamped” through an HIF-dependent mechanism, whereas HIF-independent mechanisms are responsible for downregulation of ATP consumption. In addition, we find that PHD pathway activation enables mitochondria to utilize fumarate as a terminal electron acceptor when cytochrome c oxidase is inactive. The source of fumarate for this unusual respiration is derived from aspartate via the purine nucleotide cycle. In sum, these studies show that the O2-sensing pathway is sufficient to actively “clamp” O2 consumption and independently suppress cellular ATP consumption. The PHD pathway also enables the mitochondria to utilize fumarate for respiration.

Influence of ATP turnover and metabolite changes on IMP formation and glycolysis in rat skeletal muscle

1990 ◽  
Vol 259 (3) ◽  
pp. C409-C412 ◽  
Author(s):  
K. Sahlin ◽  
J. Gorski ◽  
L. Edstrom
Keyword(s):  
Skeletal Muscle ◽  
Turnover Rate ◽  
Atp Hydrolysis ◽  
Alternative Hypothesis ◽  
Metabolic Stress ◽  
High Rate ◽  
Rat Skeletal Muscle ◽  
Muscle Lactate ◽  
Atp Turnover

Deamination of AMP to inosine monophosphate (IMP) and NH3 is thought to be regulated by the observed increases in ADP, AMP, and H+. We have examined this hypothesis by comparing the rate of IMP accumulation in contracting and noncontracting rat skeletal muscle. The rate of IMP formation was high during ischemic contraction, and consistent with previous studies, formation of IMP was associated with high levels of muscle lactate, depletion of phosphocreatine (PCr), and increased levels of ADP and AMP. When the contraction period was followed by 5-min anoxic recovery, the metabolic changes were maintained, but no further IMP or lactate was formed. During long-term (2-4 h) anoxia, the rate of IMP formation was less than 4% of that during contraction, despite similar changes in PCr, lactate, ADP, and AMP. It is concluded that the observed changes in the intracellular chemical environment are not sufficient to explain the high rate of IMP formation during contraction but that a combination of metabolic stress and a high ATP turnover rate is required. It is suggested that a high ATP turnover rate during conditions of metabolic stress results in transient increases in ADP and AMP at the site of ATP hydrolysis and that these activate AMP deaminase and glycolysis. An alternative hypothesis is that these processes are regulated by the increase in cytosolic Ca2+ in a contracting muscle.

Muscle Relaxation Rate, Fibre-Type Composition and Energy Turnover in Hyper- and Hypo-Thyroid Patients

1979 ◽  
Vol 57 (4) ◽  
pp. 375-384 ◽  
Author(s):  
C. M. Wiles ◽  
A. Young ◽  
D. A. Jones ◽  
R. H. T. Edwards
Keyword(s):  
Relaxation Rate ◽  
Fibre Type ◽  
Turnover Rate ◽  
Type Ii ◽  
Fibre Type Composition ◽  
Atp Turnover ◽  
Type Composition ◽  
Submaximal Contraction ◽  
Hypothyroid Patients ◽  
Hyperthyroid Patients

1. Quadriceps strength, relaxation rate, fibre-type composition and energy-turnover rate during a submaximal contraction have been measured in hypo- and hyper-thyroid patients and compared with findings in normal subjects. 2. Six out of eight hypothyroid patients had normal strength whereas four out of five hyperthyroid patients were weak. 3. Relaxation rate was decreased in all the hypothyroid patients but increased in only three out of five hyperthyroid patients. 4. In hypothyroidism there was a marked reduction in the percentage contributed by type II fibres to muscle cross-section, partly due to type II atrophy but also due to a decrease in the relative frequency of type II fibres. In hyperthyroidism both fibre types tended to atrophy. 5. The rate of ATP turnover during submaximal contraction held to fatigue was reduced in hypothyroidism. This was probably due to decreased ATP utilization rather than an impaired supply of energy-supplying substrates. In hyperthyroidism the rate of ATP turnover was increased. 6. Altered relaxation rate and ATP-turnover rate may be explained on the basis of changes in myosin ATPase activity with thyroid status. Changes in muscle-fibre-type composition, as determined histochemically, could not per se account for the functional abnormalities.

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