IN-VITRO P-31-MAGNETIC RESONANCE SPECTROSCOPY OF MUSCLE EXTRACTS IN MALIGNANT HYPERTHERMIA-SUSCEPTIBLE PATIENTS

Background: It was recently suggested that malignant hyperthermia-susc eptible (MHS) patients could have an elevated peak of phosphodiesters in leg muscles using in vivo phosphorus magnetic resonance spectroscop y. In the current study, analysis of the phosphodiesters of muscle ext racts of MHS and malignant hyperthermia-negative patients was performe d using in vitro phosphorus magnetic resonance spectroscopy to chemica lly identify and to compare the muscle concentrations of water-soluble compounds between the two groups with respect to the muscle fiber typ e composition. Methods: Perchloric acid extracts of the vastus mediali s muscle of seven MHS patients and ten malignant hyperthermia-negative patients on the basis of the European-malignant hyperthermia contract ure test were subjected to in vitro phosphorus magnetic resonance spec troscopy carried out at 9.4 T. In addition, chemical identification of the phosphodiester region and histologic examination of the muscle sp ecimens were performed. Results: The peak in the phosphodiester region was assigned to glycerophosphorylcholine. Muscle perchloric acid extr acts of MHS patients had a significantly (P < 0.05) higher glycerophos phorylcholine to the sum of phosphocreatine and inorganic phosphate (g lycerophosphorylcholine/[phosphocreatine +inorganic phosphate]) value than those of malignant hyperthermia-negative patients. Neither a diff erence in the fiber type composition between the two groups nor any sp ecific myopathy were found. Conclusions: In the absence of histologic differences between muscle specimens of MHS and malignant hyperthermia -negative patients, these results could suggest that glycerophosphoryl choline could be a marker of an impairment in the phospholipid metabol ism in the skeletal muscle of MHS patients.