1H-NMR of carnosine combined with 31P-NMRS to better characterize skeletal muscle pH dysregulation in Duchenne muscular dystrophy

The finding of an alkaline P_i pool has been established with 31P-NMRS in healthy resting skeletal muscle and the dystrophic muscle of GMRD dogs and DMD patients. The pH values corresponding to this P_i pool corresponds better with extracellular pH. Intracellular pH, however, can also be measured with ¹H-NMRS, using carnosine. In a group of DMD patients, we observed that pH determined with ³¹P-NMRS were systematically increased, whereas this was not always the case for pH based on the measurement of carnosine, revealing two groups in dystrophic muscle: (1) pH elevated with ³¹P and ¹H and (2) pH only elevated with ³¹P.