Long-term relationship between acute rhabdomyolysis and abnormal high-energy phosphate metabolism potentiated by...

Relative concentrations of inorganic phosphate [Pi]r, creatine phosphate [CP]r, adenosine triphosphate [ATP]r, and intracellular pH (pHi) were determined by 31P-NMR spectroscopy in the flexores digitorum muscles. The measurements were performed at rest, during bouts of rhythmic exercises at different powers, including one with restricted blood supply, and during recovery. Normal subjects (N) and subjects with previous histories of exercise hyperthermia (EH) were compared. No significant difference was found between N and EH subjects at rest. During exercise [ATP]r was not affected, except in EH subjects exercising under partial muscle ischemia (P less than 0.001); in both N and EH, [CP]r and pHi decreased, and the higher the load the more pronounced the reduction. These changes were significantly larger in EH patients than in N (P less than 0.05), and the differences were dramatically increased by reducing blood supply (P less than 0.001). During recovery, the return to the control values was much slower in EH patients than in N, in particular for pHi after the exercise under partial ischemia. In conclusion, the fact that metabolic disorders are still patent long after the EH occurrence supports the possibility of latent myopathy and of a persistent metabolic disorder. Thus, 31P-NMR spectroscopy could be a useful noninvasive test to detect EH susceptibility in at-risk subjects.