H-1-NMR DETERMINATION OF LACTATE C-13-ENRICHMENT IN SKELETAL-MUSCLE -USING A DOUBLE-QUANTUM FILTER FOR THE SIMULTANEOUS EDITING OF C-13-COUPLED AND C-13-UNCOUPLED METHYL PROTONS RESONANCE

H-1 NMR simultaneous editing of C-13-coupled and C-13-uncoupled methyl protons resonance, using the selection of double quantum coherences b y a gradient pulse, was analyzed in vitro and demonstrated in situ on the hindlimb of an exercised rat model postmortem. In vitro calibratio n showed agreement with theoretical analysis. High-resolution NMR of m uscle extract confirmed the accuracy of the lactate C-13-enrichment ca lculated using the in situ NMR data and the calibration factor obtaine d in vitro.