Energy metabolism in rat brain in vivo studied by (31)P nuclear magnetic resonance: Changes during post-natal development.

The energy metabolism in rat brains during post-natal development was followed by in vivo (31)P NMR. Using a small surface coil (7mm diameter) placed at the head of a conscious rat, high energy phosphate compounds in the brain and the steady state kinetics among them were measured. The cellular contents of some phosphate compounds changed widely during the period of post-natal cell growth from age 10 to 20 days. During the same period, the cellular activity of creatine kinase increased by a factor of more than 5 as measured by a saturation transfer technique. A method to measure the in vivo value of the creatine/creatine phosphate ratio was presented. From that ratio the cytosolic ATP/ADP ratio was estimated for brains of adult rats and neonate rats and unexpectedly the value in the latter was found to be smaller.