CREATINE AND NUCLEOSIDE TRIPHOSPHATES IN RAT CEREBRAL GRAY AND WHITE-MATTER

In vivo localized nuclear magnetic resonance spectroscopy has shown th ree-fold higher phosphocreatine/nucleoside triphosphate (PCr/NTP) rati os in cerebral white compared to gray matter. To interpret these resul ts, total creatine (Cr) and ATP concentrations were measured enzymatic ally in samples taken from rapidly frozen rat cerebral cortex and corp us callosum. Total Cr (PCr plus Cr) and ATP concentrations were the sa me in the two regions. High performance liquid chromatography showed s imilar concentrations of total NTP in the two regions. These results s uggest that higher in vivo PCr/NTP ratios in white compared to gray ma tter may be due to a higher PCr/Cr ratio in white matter and/or higher percentages of non-adenine mono- or diphosphate nucleotides in gray m atter.