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Sepsis alters skeletal muscle energetics and membrane function
D O Jacobs1, T Kobayashi, J Imagire
1Laboratory for Surgical Metabolism and Nutrition, Brigham and Women's Hospital, Harvard Medical School, Boston, Mass 02115.
Surgery
|August 1, 1991
Summary
Early sepsis increases adenosine triphosphate (ATP) utilization in skeletal muscle to maintain ionic balance. Phosphocreatine stores buffer ATP levels before significant intracellular pH changes occur, impacting muscle energetics.
Area of Science:
- Physiology
- Biochemistry
- Sepsis Research
Background:
- Sepsis significantly impacts skeletal muscle function, but its effects on energy metabolism and membrane function are not well understood.
- The temporal progression of metabolic alterations in skeletal muscle during sepsis remains unclear.
Purpose of the Study:
- To investigate the effects of early sepsis on skeletal muscle energetics and membrane function.
- To elucidate the time course of changes in energy metabolism in skeletal muscle during sepsis.
Main Methods:
- Utilized 31P magnetic resonance spectroscopy in vivo to measure high energy phosphate ratios, intracellular pH, and phosphocreatine breakdown rates in rat gastrocnemius muscle.
- Determined adenosine triphosphate (ATP) concentration and Na(+)-K+ ATPase and creatine kinase activities in vitro.
Main Results:
- Within 24 hours, sepsis induced a 60% increase in Na(+)-K+ ATPase activity.
- Phosphocreatine/ATP ratios decreased by 20%, correlating with increased phosphocreatine breakdown, while ATP concentrations and intracellular pH remained stable.
- Increased phosphocreatine breakdown was not linked to creatine kinase activity but correlated with increased adenosine 5'-diphosphate (ADP) levels.
Conclusions:
- In early sepsis, ATP is consumed at a higher rate to support ionic balance and other metabolic processes.
- Skeletal muscle utilizes phosphocreatine reserves to maintain ATP concentrations before significant intracellular acidosis develops.
- These findings clarify early sepsis-induced alterations in skeletal muscle energy metabolism and membrane function.