High-energy phosphate transfer in human muscle: Diffusion of phosphocreatine

Refaat E. Gabr, Abdel Monem M. El-Sharkawy, Michael Schär, Robert G. Weiss, Paul A. Bottomley

Research output: Contribution to journalArticlepeer-review


The creatine kinase (CK) reaction is central to muscle energetics, buffering ATP levels during periods of intense activity via consumption of phosphocreatine (PCr). PCr is believed to serve as a spatial shuttle of high-energy phosphate between sites of energy production in the mitochondria and sites of energy utilization in the myofibrils via diffusion. Knowledge of the diffusion coefficient of PCr (DPCr) is thus critical for modeling and understanding energy transport in the myocyte, but DPCr has not been measured in humans. Using localized phosphorus magnetic resonance spectroscopy, we measured DPCr in the calf muscle of 11 adults as a function of direction and diffusion time. The results show that the diffusion of PCr is anisotropic, with significantly higher diffusion along the muscle fibers, and that the diffusion of PCr is restricted to a ̃28-μm pathlength assuming a cylindrical model, with an unbounded diffusion coefficient of ̃0.69 × 10-3 mm2/s. This distance is comparable in size to the myofiber radius. On the basis of prior measures of CK reaction kinetics in human muscle, the expected diffusion distance of PCr during its half-life in the CK reaction is ̃66 μm. This distance is much greater than the average distances between mitochondria and myofibrils. Thus these first measurements of PCr diffusion in human muscle in vivo support the view that PCr diffusion is not a factor limiting high-energy phosphate transport between the mitochondria and the myofibrils in healthy resting myocytes.

Original languageEnglish (US)
Pages (from-to)C234-C241
JournalAmerican Journal of Physiology - Cell Physiology
Issue number1
StatePublished - Jul 2011


  • Creatine kinase shuttle
  • Energy metabolism
  • Human studies
  • Myocyte

ASJC Scopus subject areas

  • Physiology
  • Cell Biology


Dive into the research topics of 'High-energy phosphate transfer in human muscle: Diffusion of phosphocreatine'. Together they form a unique fingerprint.

Cite this