Napapon Sailasuta1, Brian D. Ross1,2
1Clinical MR Spectroscopy, Huntington Medical Research Institutes, Pasadena, CA, United States; 2Rudi Schulte Research Institute, Santa Barbara , CA, United States
Human brain pH is a significant clinical measure usually accomplished directly through implantable pH electrodes, or indirectly from HCO and C02 together with Henderson-Hesselbach tables. In recent 13C MRS studies we were able to directly quantify bicarbonate in resting human brain and to monitor the changes produced by short or long term fasting. pH estimated from 13C HC03 differed significantly from accepted normal values and those obtained by direct 31P MRS. Possible confounds, including binding, compartmentation and T1/T2 variances are considered before concluding that human brain [bicarbonate] is lower than previously thought.