Non-P(i) buffer capacity and initial phosphocreatine breakdown and resynthesis kinetics of human gastrocnemius/soleus muscle groups using 0.5 s time-resolved 31P MRS at 4.1 T

Bradley R. Newcomer, Michael D. Boska, Hoby P. Hetherington

Research output: Contribution to journalArticle

22 Scopus citations


High-time-resolution (0.5 s) 31P MRS has been used to evaluate the initial phosphoreatine (PCr) breakdown and resynthesis kinetics, to calculate the non-P(i)/non-bicarbonate buffer capacity (β(non-P(i)/non-bicarb)), and to calculate the constant relating the change in intracellular pH to the muscle's H+ efflux rate (λ). The slope of PCr vs time demonstrates that a slope calculated using the first 10 s of recovery underestimates initial PCr recovery rates by up to 56%. A 1-2 s time window is needed to produce a slope that is statistically equivalent to the slope measured using a 0.5 s time window (p = 0.008, one-way RM-ANOVA, Student-Newman-Keuls multiple comparison test). In addition, there was no delay or acceleration in PCr recovery after a 90 s maximum voluntary contraction (MVC) in normal subjects. This demonstrates that oxidative metabolism is occurring at the end of a 90-s MVC in normal individuals. Fitting recovery data has determined that β(non- P(i)/non-bicarb) = 24.3 ± 5.4 slyke (mmol/L/pH unit) and that λ=0.129 ± 0.077 mM/(ph s) for human gastrocnemius/soleus muscle. β(non-P(i)/non- bicarb) is in agreement with measurements in cat biceps, cat soleus and rat gastrocnemius muscles. (C) 1999 John Wiley and Sons, Ltd.

Original languageEnglish (US)
Pages (from-to)545-551
Number of pages7
JournalNMR in Biomedicine
Issue number8
Publication statusPublished - Dec 1 1999



  • Non-P(i) buffer capacity
  • P of exercising muscle

ASJC Scopus subject areas

  • Molecular Medicine
  • Radiology Nuclear Medicine and imaging
  • Spectroscopy

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