title: Changes in high-energy phosphates in rat skeletal muscle during acute respiratory acidosis.
abstract: We used 31P magnetic resonance spectroscopy to study changes in phosphorus metabolite concentrations in rat skeletal muscle during respiratory acidosis (14 and 20% inspired CO2) and recovery. As intracellular pH fell (from 7.05 to 6.75 after 20 min of 20% CO2), intracellular [P(i)] increased by up to 50% while phosphocreatine concentration decreased by up to 8%. The sum of all intracellular phosphates remained constant. [ADP] decreased by up to 40% in accordance with the creatine kinase equilibrium but the phosphorylation potential [ATP]/([ADP][P(i)]) was preserved as a result of increased [P(i)]. This adjustment may be a mechanism for maintaining mitochondrial ATP synthesis despite low pH. Eventually this increase in cellular [P(i)] could lead to slow efflux of P(i) from the skeletal muscle cell contributing to the hyperphosphataemia of acute respiratory acidosis.
authors.affiliation: M.R.C. Biochemical and Clinical Magnetic Resonance Unit, John Radcliffe Hospital, Oxford, UK.
authors.forename: C H
authors.initials: CH
authors.lastname: Thompson
authors.forename: G J
authors.initials: GJ
authors.lastname: Kemp
authors.forename: G K
authors.initials: GK
authors.lastname: Radda
mesh_terms: D000142:Acidosis, Respiratory / Q000378:metabolism*; D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002245:Carbon Dioxide / Q000378:metabolism; D003401:Creatine / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008297:Male; D009132:Muscles / Q000378:metabolism*; D010710:Phosphates / Q000378:metabolism*; D010725:Phosphocreatine / Q000378:metabolism; D010766:Phosphorylation; D051381:Rats; D017208:Rats, Wistar
chemical_list: D010710:Phosphates; D010725:Phosphocreatine; D002245:Carbon Dioxide; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D003401:Creatine