Kinetics of creatine kinase in an experimental model of low phosphocreatine and ATP in the normoxic heart

An acute normoxic model of steady-state depletion of phosphocreatine and adenylate in rat heart was designed to investigate the dependence of the forward flux of creatine kinase (CK) on its products and substrates. The flux and apparent rate constant of CK were measured by nuclear magnetic resonance (NMR). Meanwhile, evidences for sustained cystosolic transfer of energy at high adenosine triphosphate content were presented. A comparison was made on NMR-measured flux and flux computed under the CK equilibrium hypothesis. CK flux was not predicted fully by CK metabolite concentrations.