MAGNETIZATION-TRANSFER STUDY OF CREATINE-KINASE IN MYOCARDIUM - POTENTIAL CLINICAL INTEREST OF IN-VIVO ENZYMOLOGY

Since myocardial contractility relies on the continuous balance of ATP synthesis and ATP degradation, a dynamic estimation of the high energ y phosphates (HEP) turnover by magnetization transfer P-31 NMR spectro scopy appears to be a more valuable index of heart function than the s tatic evaluation of HEP concentrations. The theory of the main magneti zation transfer techniques (saturation transfer, inversion transfer) i s described as well as a critical evaluation of their application to t he determination of creatine kinase (CK) fluxes in myocardium. The det erminants of CK flux in vivo is evaluated (total CK activity, isozymic CK expression and concentrations of CK substrates and products). CK f lux is shown to vary in relation to contractility during short term st ress (hypoxia, ischemia) and in long term adaptation or pathology of t he myocardium. The dynamic estimation of energetic flux in vivo is pro posed as a non-invasive tool of diagnosis in myocardial pathologies.