Determination of muscle pH and glycolytic flux by magnetic resonance spectroscopy in contracting human skeletal muscle may have systematic errors

2005 ◽  
Vol 289 (1) ◽  
pp. C230-C230 ◽  
Author(s):  
Kent Sahlin
2019 ◽  
Author(s):  
Vinicius da Eira Silva ◽  
Vitor de Salles Painelli ◽  
Samuel Katsuyuki Shinjo ◽  
Wagner Ribeiro Pereira ◽  
Eduardo Maffud Cilli ◽  
...  

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.


2018 ◽  
Vol 43 (6) ◽  
pp. 647-649 ◽  
Author(s):  
Sergej M. Ostojic ◽  
Jelena Ostojic

We analyzed data from previously completed trials to determine the effects of supplemental guanidinoacetic acid (GAA) on markers of muscle bioenergetics in healthy men using 1.5 T magnetic resonance spectroscopy. No detectable GAA (<0.1 μmol/L) was found in the vastus medialis muscle at baseline nor at follow-up. This implies deficient GAA availability in the human skeletal muscle, suggesting absent or negligible potential for creatine synthesis from GAA inside this tissue, even after GAA loading.


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