Phosphate metabolites in single barnacle muscle fibers investigated by phosphorus-31 nuclear magnetic resonance

Abstract

1. 1. A study has been made of phosphate-containing metabolites in single barnacle muscle fibers using phosphorus-31 nuclear magnetic resonance. 2. 2. Spectra from single fibers (∼50 mg in wet weight) show major resonances from sugar phosphates, inorganic phosphate, arginine phosphate and the α, β and γ phosphorus atoms of ATP. 3. 3. The approximate “free” concentration of each metabolite was determined by integration of the spectrum, using a sample of 1 M-methylene diphosphonic acid as a reference. A notable feature of the results obtained is that the concentrations of SP&P i in freshly dissected fibers are low. 4. 4. Time-dependent changes in 31P-NMR spectra indicate that ArP declines fairly slowly, while SP and P i rises. The half-life of ArP at 26°C turns out to be about 8 hr. ATP remains relatively constant for the first 8 hr but disappears following the disappearance of ArP. As the intensity of the P i resonance increases with time, it broadens and moves upfield, suggesting internal acidosis. 5. 5. These results demonstrate that 31P-NMR can provide useful information about metabolism and its regulation in single barnacle muscle fibers.