The carnosine C-2 proton's chemical shift reports intracellular pH in oxidative and glycolytic muscle fibers.

Damon BM, Hsu AC, Stark HJ, Dawson MJ
Magn Reson Med. 2003 49 (2): 233-40

PMID: 12541242 · DOI:10.1002/mrm.10384

The appearance of new peaks in the 7.7-8.6 and 6.8-7.4 ppm regions of the postexercise (1)H spectrum of frog muscle is reported. These new peaks result from the splitting of single pre-exercise carnosine C-2 and C-4 peaks into two peaks, representing the intracellular pH (pH(I)) of oxidative and glycolytic fibers. The following data support this conclusion: 1) comparison of means and regression analysis indicates equivalence of the pH(I) measurements by (1)H and (31)P NMR; 2) the pre- and poststimulation concentrations of carnosine are equal; 3) in ischemic rat hindlimb muscles, the presence of a single, more acidic peak in the plantaris; a single, less acidic peak in the soleus; and two peaks (more and less acidic) in the gastrocnemius correspond to published values for the fiber-type composition of these muscles; and 4) in muscles treated with iodoacetate prior to and during stimulation, a second peak never appears. These data indicate that it is feasible to measure separately the pH(I) of oxidative and glycolytic fibers using (1)H NMR spectroscopy.

Copyright 2003 Wiley-Liss, Inc.

MeSH Terms (14)

Animals Carnosine Glycolysis Hindlimb Hydrogen-Ion Concentration In Vitro Techniques Isometric Contraction Magnetic Resonance Spectroscopy Muscle, Skeletal Muscle Fibers, Fast-Twitch Muscle Fibers, Slow-Twitch Oxidation-Reduction Rana pipiens Rats

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