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Effects of Hypoxic Hypoxia on Cerebral Phosphate Metabolites and pH in the Anesthetized Infant Rabbit

1985; SAGE Publishing; Volume: 5; Issue: 4 Linguagem: Inglês

10.1038/jcbfm.1985.77

1559-7016

Ricardo González‐Méndez, Ann McNeill, George A. Gregory, Susan D. Wall, Charles A. Gooding, Lawrence Litt, Thomas Leroy James,

Lipid Membrane Structure and Behavior

The effects of hypoxic hypoxia on high-energy phosphate metabolites and intracellular pH (pH i ) in the brain of the anesthetized infant rabbit were studied in vivo using 31 P nuclear magnetic resonance spectroscopy. Five 10- to 16-day-old rabbits were anesthetized with 1.5% halothane. Ventilation was controlled to maintain normocarbia. Inspired O 2 fraction was adjusted to produce three states of arterial oxygenation: hyperoxia (P a o 2 > 250 mm Hg), normoxia (P a o 2 ∼ 100 mm Hg), and hypoxia (P a o 2 25–30 mm Hg). During hypoxia, blood pressure was kept within 20% of control values with a venous infusion of epinephrine. During hyperoxia, the phosphocreatine-to-ATP ratio was 0.86, a value that is 2–2.5 times less than that reported for adults. During normoxia, ATP decreased by 20% and P i increased by 90% from hyperoxia values. During 60 min of hypoxia, the concentrations of high-energy phosphate metabolites did not change, but intracellular and arterial blood pH (pH a ) decreased significantly. When hyperoxia was reestablished, pH i returned to normal and pH a remained low. These results suggest that during periods of hypoxemia, the normotensive infant rabbit maintains intracellular concentrations of cerebral high-energy phosphates better than has been reported for adult animals.