Recovery of free ADP, Pi, and free energy of ATP hydrolysis in human skeletal muscle

1998 ◽  
Vol 85 (6) ◽  
pp. 2140-2145 ◽  
Author(s):  
Henning Wackerhage ◽  
Uwe Hoffmann ◽  
Dieter Essfeld ◽  
Dieter Leyk ◽  
Klaus Mueller ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Nuclear Magnetic Resonance ◽  
Free Energy ◽  
Magnetic Resonance ◽  
Oxidative Phosphorylation ◽  
Human Skeletal Muscle ◽  
Atp Hydrolysis ◽  
Resonance Spectroscopy ◽  
Atp Production ◽  
Production And Consumption

We measured significant undershoots of the concentrations of free ADP ([ADP]) and Pi([Pi]) and the free energy of ATP hydrolysis (Δ G ATP) below initial resting levels during recovery from severe ischemic exercise with 31P-nuclear magnetic resonance spectroscopy in 11 healthy sports students. Undershoots of the rate of oxidative phosphorylation would be predicted if the rate of oxidative phosphorylation would depend solely on free [ADP], [Pi], or Δ G ATP. However, undershoots of the rate of oxidative phosphorylation have not been reported in the literature. Furthermore, undershoots of the rate of oxidative phosphorylation are unlikely because there is evidence that a balance between ATP production and consumption cannot be achieved if an undershoot of the rate of oxidative phosphorylation actually occurs. Therefore, oxidative phosphorylation seems to depend not only on free [ADP], [Pi], or Δ G ATP. An explanation is that acidosis-related or other factors control oxidative phosphorylation additionally, at least under some conditions.

scholarly journals Quasi-linear relationship between Gibbs free energy of ATP hydrolysis and power output in human forearm muscle

1995 ◽  
Vol 268 (6) ◽  
pp. C1474-C1484 ◽  
Author(s):  
J. A. Jeneson ◽  
H. V. Westerhoff ◽  
T. R. Brown ◽  
C. J. Van Echteld ◽  
R. Berger
Keyword(s):  
Skeletal Muscle ◽  
Free Energy ◽  
Oxidative Phosphorylation ◽  
Power Output ◽  
Atp Hydrolysis ◽  
Adenine Nucleotide ◽  
Resonance Spectroscopy ◽  
Mammalian Skeletal Muscle ◽  
Flexor Muscle ◽  
Linear Description

The postulated strictly linear descriptions of the rate dependence of oxidative phosphorylation in skeletal muscle on the free energy of ATP hydrolysis (delta GP) over the range of physiological steady states fail to harmonize with reported findings of identical basal respiration rates in mammalian muscles at different delta GP values. The relevance of an extension of the strictly linear description to a description deriving from enzyme kinetics that predicts a sigmoidal dependence was investigated in human finger flexor muscle using 31P-nuclear magnetic resonance spectroscopy. At constant pH 7.0, the experimental variation of adenine nucleotide concentrations with power output, which reflects the rate of oxidative phosphorylation, was compared with predictions by various formulations of adenine nucleotide control of respiration. The quasi-linear sigmoidal description was found to be statistically equivalent but physiologically superior to the strictly linear description. The predicted maximal oxidatively sustained steady-state power output and rate-dependent sensitivity of respiration to changes in delta GP were in agreement both with theoretical considerations and with experimental observations in the present study and other studies of intact mammalian skeletal muscle.

Interrelationship of oxidative metabolism and local perfusion demonstrated by NMR in human skeletal muscle

1996 ◽  
Vol 81 (5) ◽  
pp. 2221-2228 ◽  
Author(s):  
Jean-François Toussaint ◽  
Kenneth K. Kwong ◽  
Fidelis M’Kparu ◽  
Robert M. Weisskoff ◽  
Paul J. Laraia ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Magnetic Resonance ◽  
Time Constant ◽  
Oxidative Metabolism ◽  
Human Skeletal Muscle ◽  
Plantar Flexion ◽  
High Energy ◽  
Resonance Spectroscopy ◽  
Mean Flow ◽  
Normal Volunteers

Toussaint, Jean-François, Kenneth K. Kwong, Fidelis M’Kparu, Robert M. Weisskoff, Paul J. LaRaia, and Howard L. Kantor.Interrelationship of oxidative metabolism and local perfusion demonstrated by NMR in human skeletal muscle. J. Appl. Physiol. 81(5): 2221–2228, 1996.—Using nuclear magnetic resonance (NMR), we have examined the relationship of high-energy phosphate metabolism and perfusion in human soleus and gastrocnemius muscles. With31P-NMR spectroscopy, we monitored phosphocreatine (PCr) decay and recovery in eight normal volunteers and four heart failure patients performing ischemic plantar flexion. By using echo-planar imaging, perfusion was independently measured by a local [inversion-recovery (T1-flow)] and a regional technique (NMR-plethysmography). After correction for its pH dependence, PCr recovery time constant is 27.5 ± 8.0 s in normal volunteers, with mean flow 118 ± 75 (soleus and gastrocnemius T1-flow) and 30.2 ± 9.7 ml ⋅ 100 ml−1 ⋅ min−1(NMR-plethysmography-flow). We demonstrate a positive correlation between PCr time constant and local perfusion given by y = 50 − 0.15 x( r 2 = 0.68, P = 0.01) for the 8 normal subjects, and y = 64 − 0.24 x( r 2 = 0.83, P = 0.0001) for the 12 subjects recruited in the study. Regional perfusion techniques also show a significant but weaker correlation. Using this totally noninvasive method, we conclude that aerobic ATP resynthesis is related to the magnitude of perfusion, i.e., O2availability, and demonstrate that magnetic resonance imaging and magnetic resonance spectroscopy together can accurately assess muscle functional status.

scholarly journals Magnetic Resonance Spectroscopy as a Non-invasive Method to Quantify Muscle Carnosine in Humans: a Comprehensive Validity Assessment

2019 ◽  
Author(s):  
Vinicius da Eira Silva ◽  
Vitor de Salles Painelli ◽  
Samuel Katsuyuki Shinjo ◽  
Wagner Ribeiro Pereira ◽  
Eduardo Maffud Cilli ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Magnetic Resonance ◽  
Magnetic Resonance Spectroscopy ◽  
Human Skeletal Muscle ◽  
Reference Method ◽  
Resonance Spectroscopy ◽  
Muscle Carnosine ◽  
1H Mrs ◽  
Non Invasive

ABSTRACTCarnosine is a dipeptide abundantly found in human skeletal muscle, cardiac muscle and neuronal cells having numerous properties that confers performance enhancing effects, as well as a wide-range of potential therapeutic applications. A reliable and valid method for tissue carnosine quantification is crucial for advancing the knowledge on biological processes involved with carnosine metabolism. In this regard, proton magnetic resonance spectroscopy (1H-MRS) has been used as a non-invasive alternative to quantify carnosine in human skeletal muscle. However, carnosine quantification by 1H-MRS has some potential limitations that warrant a thorough experimental examination of its validity. The present investigation examined the reliability, accuracy and sensitivity for the determination of muscle carnosine in humans using in vitro and in vivo experiments and comparing it to reference method for carnosine quantification (high-performance liquid chromatography – HPLC). We used in vitro 1H-MRS to verify signal linearity and possible noise sources. Carnosine was determined in the m. gastrocnemius by 1H-MRS and HPLC to compare signal quality and convergent validity. 1H-MRS showed adequate discriminant validity, but limited reliability and poor agreement with a reference method. Low signal amplitude, low signal-to-noise ratio, and voxel repositioning are major sources of error.

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