Measurement of unidirectional Pi to ATP flux in human visual cortex at 7 T by using in vivo 31P magnetic resonance spectroscopy

Taking advantage of the high NMR detection sensitivity and the large chemical shift dispersion offered by ultra-high field strength of 7 T, the effect of magnetization transfer on inorganic phosphate (Pi) resonance during saturation of gamma-ATP resonance, mediated by the ATP synthesis reaction, was observed noninvasively in the human primary visual cortex by using in ViVo P-31 magnetic resonance spectroscopy. The unidirectional flux from P-i to ATIP was measured by using progressive saturation transfer experiments. The cerebral ATP synthesis rate in the human primary visual cortex measured by P-31 magnetic resonance spectroscopy in this study was 12.1 +/- 2.8 mumol ATP/g per min, which agreed well with the value that was calculated indirectly from the cerebral metabolic rate of glucose consumption reported previously.