Double quantum (DQ), J-resolved (1)H NMR spectra from rat and bovine skeletal muscle showed a splitting frequency ( approximately 24 Hz) for the lactate methyl protons that varied with the orientation of the muscle fibers relative to the magnetic field. In contrast, spectra of lactate in solution co
Correlation of lactate and pH in human skeletal muscle after exercise by 1H NMR
β Scribed by J. W. Pan; J. R. Hamm; H. P. Hetherington; D. L. Rothman; R. G. Shulman
- Publisher
- John Wiley and Sons
- Year
- 1991
- Tongue
- English
- Weight
- 517 KB
- Volume
- 20
- Category
- Article
- ISSN
- 0740-3194
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β¦ Synopsis
Abstract
We have made in vivo ^1^H NMR measurements of the time course of pH and lactate in human skeletal muscle after exercise. Spectra were obtained in a 4.7βT 30 cm bore Bruker Biospec spectrometer with a 2.5βcm diameter single surface coil. pH was determined from the shift of the endogenous carnosine HβC~2~ peak while lactate concentrations were determined by comparison with endogenous total creatine, taken to be 28.5 m__M__/ kg wet wt. Fitting the data shows that the exponential decay of lactate (β0.094 Β± 0.014 min ^β1^, t 1/2 = 10.6 min) is slower than that of pH (β0.147 Β± 0.015 min^β1^, t~1/2~ = 4.7 min), n = 7 with two different volunteers. These values are significantly different with P < 0.0005. Relaxation times of lactate and creatine were also measured for lactate quantitation: creatine Tl. 1.23 Β± 12 s. T2, 136.2 Β± 26.4 ms (both in resting human muscle); lactate Tl (in postmortem rabbit muscle), 1.0 Β± 11 s and T2, 80 ms (in postexercise human muscle). At the end of intense exercise, the lactate level reached was 25.3 Β± 4.0 m M and the average pH drop was 1.0 pH unit. We discuss the implicaions of these measurements in conjunction with existing data on other sources of H^+^ flux, phosphocreatine resynthesis, H^+^ transport, and contribution of inorganic phosphate to buffering. Β© 1991 Academic Press, Inc.
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