Phosphorus Spectroscopy of Calf Muscles before and after Exercise

BACKGROUND: The aim of this study was to determine (31)PMRS reference spectrum and intracellular pH of calf muscles in the dominant limb of healthy, young, male volunteers before and after intense physical effort. MATERIAL/METHODS: Examinations were performed with a 1.5 T MR system. FID CSI (Free Induction Decay Chemical Shift Imaging) sequence was used with the following parameters: TR=4000 ms, FA=90°, NEX=2 and VOI (Volume Of Interest)=8×8×8 cm(3) (512 cm(3)) involving in calf muscles. Raw data was preprocessed using SAGE (GE) software. Authors analyzed relative concentrations ratios of selected metabolites: PCr/ATP and PCr/P(i). Intracellular pH and relative concentrations ratios of each metabolite (P(i), PCr, α-ATP, β-ATP, γ-ATP, ATP) were also calculated relative to the sum of concentrations of all metabolites. Results were compared with a t-test. RESULTS: Based on statistical analysis of results significant differences (p<0.05) were demonstrated for some of the studied metabolites and for intracellular pH. Increase in PCr concentration in relation to the sum of concentrations of all metabolites and to ATP concentration was noted. However, β-ATP, α-ATP and ATP concentrations relative to the sum of concentrations of all metabolites become reduced. Decrease in pH after physical effort was demonstrated. There were no significant differences (p<0.05) in concentrations of remaining metabolites before and after exercise. Increase in PCr concentration relative to P(i) concentration and decrease of P(i) and γ-ATP concentration relative to the sum of concentrations of all metabolites were demonstrated. CONCLUSIONS: The (31)PMRS method enables assessment of concentrations of phosphorus-containing metabolites as well as intercellular pH before and after exercise. This method is still under examination, but it has already shown promise as a diagnostic tool for the future.