Brain maturation and response to anoxia: 31P NMR spectroscopic studies in rat pups

The differential effects of systemic anoxia on the immature rat brain in two postnatal developmental age groups, group I (1-2 days postnatal) and group II (9-10 days postnatal), were studied utilizing phosphorus-31 nuclear magnetic resonance spectroscopy. While all pups in group I survived the 15-min anoxic period, only half of the pups in group II survived. Brain adenosine triphosphate and intracellular pH of pups in group I remained essentially unchanged throughout the anoxic period, while phosphocreatine and inorganic phosphate were sensitive indicators of anoxia. These parameters were all more drastically affected in group II pups than in group I pups. Group II pups also exhibited a significant increase in phosphomonoester, indicating developmental differences in phospholipid metabolism.