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Abstract #0685

Kinetics of Muscle Lactate and High Energy Phosphates Measured by Localised Quantitative Interleaved MRS During Recovery from Ischaemic Exercise Define the Contributions of Lactate Oxidation, Lactate Efflux and Other Processes of Acid Efflux

Graham Kemp1, Martin Meyerspeer2,3, Ewald Moser2,4

1Magnetic Resonance and Image Analysis Research Centre, University of Liverpool, Liverpool, Merseyside, UK; 2MR Centre of Excellence, Medical University of Vienna, Vienna, Austria; 3Center for Biomedical Engineering and Physics, Medical University of Vienna, Vienna, Austria; 4Department of Radiology, Medical University of Vienna, Vienna, Austria

31P MRS offers insight into skeletal muscle bioenergetics, but can only measure some of what is of interest. A quantitative 1H MRS method for muscle lactate interleaved with 31P MRS permits fuller quantification of the processes responsible for production and buffering of metabolic acid. In recovery from ischaemic exercise (n=5) we used lactate, pH and PCr measurements to quantify the processes responsible for clearing the acid load to permit recovery of pH. We conclude that oxidation can be only a minor contribution, the majority of lactate being exported, this being however, only a small contribution to overall acid clearance.