title: An in vivo 31P-NMR study of the possible regulation of glycogen phosphorylase a by phosphagen via phosphate in the abdominal muscle of the shrimp Crangon crangon.
abstract: 31P-NMR spectroscopy has been used to determine the concentrations of Pi and phosphagen in the abdominal muscle of the shrimp Crangon crangon at rest and to follow the changes during their recovery after exhaustive work in vivo. Additionally, the effect of physiological Pi concentrations to the phosphorylase a activity has been examined. At rest, the cytoplasmic Pi and phosphagen concentrations were 1 mM and 38 mM, respectively. After exhaustive work the concentrations of both metabolites were in the same range (20 mM). During recovery, the time course of phosphagen regeneration correlates with the decrease of Pi, as the sum of the concentrations of these metabolites is constant. The ATP level was stable throughout the experiment. The phosphorylase a, which was already present in the resting muscle, was virtually inactive at the resting Pi level (1 mM). During work, however, Pi, which is probably generated by phosphagen-ATP splitting, might ensure a sufficient activation of phosphorylase a.
mesh_terms: D000227:Adenine Nucleotides / Q000378:metabolism; D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives* / Q000378:metabolism; D033364:Decapoda; D009682:Magnetic Resonance Spectroscopy; D009119:Muscle Contraction; D009132:Muscles / Q000378:metabolism*; D009943:Organophosphorus Compounds / Q000378:metabolism; D010710:Phosphates / Q000378:metabolism*; D006005:Phosphorylases / Q000378:metabolism*; D005082:Physical Exertion; D013403:Sugar Phosphates / Q000378:metabolism
chemical_list: D000227:Adenine Nucleotides; D009943:Organophosphorus Compounds; D010710:Phosphates; D013403:Sugar Phosphates; C015441:phospho-L-arginine; D001120:Arginine; D006005:Phosphorylases