Metabolic response to exercise in malignant hyperthermia-sensitive patients measured by 31P magnetic resonance spectroscopy.
The currently favored theory of pathogenesis of malignant hyperthermia (MH) implicates an abnormality in skeletal muscle calcium ion transport. During a MH crisis a profound lactic acidosis occurs and in MH-sensitive individuals a delayed recovery of venous lactate has been previously noted postexercise. We have used 31P magnetic resonance spectroscopy to follow noninvasively in vivo changes in muscle of intracellular pH and high-energy phosphate metabolites during rest, exercise, and recovery of MH-sensitive subjects. Eleven biopsy-positive MH-sensitive patients have been studied and compared to 26 normal subjects. The MH-sensitive subjects as a group prematurely dropped their intracellular pH during mild aerobic exercise and they demonstrated a marked delay before the recovery of pH after maximal exercise. PCr/(PCr + Pi) ratios also dropped early during exercise but recovered normally. The observed changes in pH and PCr/(PCr + Pi) are consistent with a myopathy in MH-susceptible individuals.
Webster
D W
DW
Department of Nuclear Medicine, Victoria Hospital, Ontario, Canada.
Thompson
R T
RT
Gravelle
D R
DR
Laschuk
M J
MJ
Driedger
A A
AA
D000255:Adenosine Triphosphate / Q000032:analysis*; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008305:Malignant Hyperthermia / Q000175:diagnosis*; D009132:Muscles / Q000032:analysis*; D010710:Phosphates / Q000032:analysis*; D010725:Phosphocreatine / Q000032:analysis*
D010710:Phosphates; D010725:Phosphocreatine; D000255:Adenosine Triphosphate