EFFECTS OF FASTING, INTERMITTENT FEEDING, OR CONTINUOUS PARENTERAL-NUTRITION ON RAT-LIVER AND BRAIN ENERGY-METABOLISM AS ASSESSED BY P-31-NMR

We wanted to determine what happens to brain PCr and ATP relative to t hat in liver during a series of dietary manipulation consisting of a s evere fast, during eating (when nutrients are intermittently supplied) , and during and after PN-100, when an excess amount of nutrients are continuously supplied, using P-31-NMR spectroscopy, in rats randomized to a Fast or Fed group in which energy was provided either as chow or as PN-100. Liver ATP concentration, and brain and liver P-31-nuclear magnetic resonance (NMR) spectras were measured serially. Brain energy metabolism was not different between groups and among days. In contra st, Fasted group showed increased liver ATP/Pi ratio and decreased ATP concentration and ATP/phosphomonoester ratio, there being no differen ce between Fed and PN-100 groups. Data suggest that brain energy metab olism is maintained regardless of whether energy is supplied intermitt ently or continuously, and during a negative caloric intake period, br ain energy metabolism is quantitatively preserved, suggesting that ATP production by liver is subservient to brain ATP state.